{"id":20121,"date":"2025-12-01T14:52:55","date_gmt":"2025-12-01T06:52:55","guid":{"rendered":"https:\/\/viox.com\/?p=20121"},"modified":"2025-11-16T15:02:14","modified_gmt":"2025-11-16T07:02:14","slug":"load-center-vs-panelboard-nec-guide","status":"publish","type":"post","link":"https:\/\/test.viox.com\/vi\/load-center-vs-panelboard-nec-guide\/","title":{"rendered":"Trung t\u00e2m t\u1ea3i so v\u1edbi B\u1ea3ng \u0111i\u1ec1u khi\u1ec3n: H\u01b0\u1edbng d\u1eabn l\u1ef1a ch\u1ecdn c\u1ee7a k\u1ef9 s\u01b0 (V\u1edbi c\u00e1c y\u00eau c\u1ea7u c\u1ee7a NEC)"},"content":{"rendered":"<div class=\"product-intro\">\n<article>Gi\u1ea5y ph\u00e9p \u0111\u00e3 \u0111\u01b0\u1ee3c ph\u00ea duy\u1ec7t. Vi\u1ec7c l\u1eafp \u0111\u1eb7t \u0111\u00e3 ho\u00e0n t\u1ea5t. \u0110\u00e3 \u0111\u1ea7u t\u01b0 15.000 \u0111\u00f4 la. Thanh tra \u0111i\u1ec7n \u0111\u1ebfn v\u00e0o s\u00e1ng th\u1ee9 Ba, k\u1eb9p gi\u1ea5y tr\u00ean tay, v\u00e0 \u0111i th\u1eb3ng \u0111\u1ebfn b\u1ea3ng ph\u00e2n ph\u1ed1i \u0111i\u1ec7n m\u1edbi l\u1eafp \u0111\u1eb7t c\u1ee7a b\u1ea1n\u2014b\u1ea3ng m\u00e0 b\u1ea1n ch\u1ec9 \u0111\u1ecbnh l\u00e0 trung t\u00e2m t\u1ea3i v\u00ec gi\u00e1 c\u1ea3 ph\u1ea3i ch\u0103ng v\u00e0 t\u00f2a nh\u00e0 c\u00f3 v\u1ebb \u0111\u1ee7 nh\u1ecf. B\u00fat c\u1ee7a anh ta l\u01a1 l\u1eedng tr\u00ean gi\u1ea5y ph\u00e9p. \u201cC\u00e1i n\u00e0y s\u1ebd kh\u00f4ng \u0111\u1ea1t.\u201d Th\u1ebb \u0111\u1ecf. Vi\u1ec7c x\u00e2y d\u1ef1ng cho thu\u00ea th\u01b0\u01a1ng m\u1ea1i c\u1ee7a b\u1ea1n v\u1eeba tr\u1edf th\u00e0nh m\u1ed9t vi\u1ec7c l\u00e0m l\u1ea1i ho\u00e0n to\u00e0n, v\u00e0 nh\u00e0 th\u1ea7u ch\u00ednh \u0111\u00e3 b\u1eaft \u0111\u1ea7u t\u00ednh to\u00e1n c\u00e1c kho\u1ea3n ph\u1ea1t ch\u1eadm tr\u1ec5.<\/p>\n<p>B\u1ea1n \u0111\u00e3 b\u1ecf l\u1ee1 \u0111i\u1ec1u g\u00ec? V\u00e0 quan tr\u1ecdng h\u01a1n, l\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 b\u1ea1n ch\u1ecdn gi\u1eefa trung t\u00e2m t\u1ea3i v\u00e0 b\u1ea3ng \u0111i\u1ec7n \u0111\u1ec3 \u0111i\u1ec1u n\u00e0y kh\u00f4ng bao gi\u1edd x\u1ea3y ra n\u1eefa?<\/p>\n<p>C\u00e2u tr\u1ea3 l\u1eddi kh\u00f4ng n\u1eb1m \u1edf \u0111\u1ecbnh m\u1ee9c \u0111i\u1ec7n \u00e1p ho\u1eb7c s\u1ef1 kh\u00e1c bi\u1ec7t v\u1ec1 gi\u00e1. N\u00f3 \u0111\u01b0\u1ee3c ch\u00f4n trong \u0110i\u1ec1u 408 c\u1ee7a NEC, c\u00e1c y\u00eau c\u1ea7u li\u1ec7t k\u00ea UL 67 v\u00e0 m\u1ed9t s\u1ed1 ti\u00eau ch\u00ed l\u1ef1a ch\u1ecdn m\u00e0 h\u1ea7u h\u1ebft c\u00e1c b\u1ea3ng th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt \u0111\u1ec1u b\u1ecf qua m\u1ed9t c\u00e1ch thu\u1eadn ti\u1ec7n. H\u00e3y kh\u1eafc ph\u1ee5c \u0111i\u1ec1u \u0111\u00f3.<\/p>\n<h2>Trung T\u00e2m T\u1ea3i So V\u1edbi B\u1ea3ng \u0110i\u1ec7n: S\u1ef1 Th\u1eadt Ph\u00e1p L\u00fd<\/h2>\n<p>\u0110\u00e2y l\u00e0 \u0111i\u1ec1u m\u00e0 nh\u00e0 ph\u00e2n ph\u1ed1i \u0111i\u1ec7n c\u1ee7a b\u1ea1n s\u1ebd kh\u00f4ng n\u00f3i v\u1edbi b\u1ea1n: <strong>theo <a href=\"https:\/\/up.codes\/s\/switchboards-switchgear-and-panelboards\" rel=\"nofollow noopener\" target=\"_blank\">\u0110i\u1ec1u 408 c\u1ee7a NEC<\/a> v\u00e0 <a href=\"https:\/\/www.ul.com\/thecodeauthority\/knowledge\/panelboards-guide\" rel=\"nofollow noopener\" target=\"_blank\">Ti\u00eau chu\u1ea9n UL 67<\/a>, kh\u00f4ng c\u00f3 s\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa \u201ctrung t\u00e2m t\u1ea3i\u201d v\u00e0 \u201cb\u1ea3ng \u0111i\u1ec7n\u201d.\u201d<\/strong><\/p>\n<p>C\u1ea3 hai thu\u1eadt ng\u1eef \u0111\u1ec1u \u0111\u1ec1 c\u1eadp \u0111\u1ebfn c\u00f9ng m\u1ed9t th\u1ee9\u2014m\u1ed9t c\u1ee5m ph\u00e2n ph\u1ed1i v\u1edbi c\u00e1c thanh c\u00e1i v\u00e0 thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf \u0111\u1ec3 \u0111\u1eb7t trong t\u1ee7 ho\u1eb7c v\u1ecf b\u1ecdc. NEC ch\u1ec9 s\u1eed d\u1ee5ng m\u1ed9t t\u1eeb: b\u1ea3ng \u0111i\u1ec7n. UL 67 (ti\u00eau chu\u1ea9n chi ph\u1ed1i vi\u1ec7c ki\u1ec3m tra v\u00e0 li\u1ec7t k\u00ea) s\u1eed d\u1ee5ng c\u00f9ng m\u1ed9t thu\u1eadt ng\u1eef duy nh\u1ea5t. \u201cTrung t\u00e2m t\u1ea3i\u201d l\u00e0 thu\u1eadt ng\u1eef ti\u1ebfp th\u1ecb xu\u1ea5t hi\u1ec7n \u1edf B\u1eafc M\u1ef9 \u0111\u1ec3 m\u00f4 t\u1ea3 c\u00e1c b\u1ea3ng \u0111i\u1ec7n nh\u1ecf h\u01a1n, chi ph\u00ed th\u1ea5p h\u01a1n \u0111\u01b0\u1ee3c b\u00e1n ch\u1ee7 y\u1ebfu cho c\u00e1c \u1ee9ng d\u1ee5ng d\u00e2n d\u1ee5ng.<\/p>\n<p>V\u00ec v\u1eady, n\u1ebfu ch\u00fang gi\u1ed1ng h\u1ec7t nhau v\u1ec1 m\u1eb7t ph\u00e1p l\u00fd, t\u1ea1i sao s\u1ef1 kh\u00e1c bi\u1ec7t l\u1ea1i quan tr\u1ecdng? B\u1edfi v\u00ec <strong>s\u1ef1 kh\u00e1c bi\u1ec7t v\u1ec1 c\u1ea5u tr\u00fac v\u1eadt l\u00fd<\/strong> v\u00e0 <strong>c\u00e1c bi\u1ebfn th\u1ec3 li\u1ec7t k\u00ea UL<\/strong> t\u1ea1o ra nh\u1eefng kho\u1ea3ng tr\u1ed1ng hi\u1ec7u su\u1ea5t th\u1ef1c t\u1ebf c\u00f3 th\u1ec3 gi\u1ebft ch\u1ebft vi\u1ec7c l\u1eafp \u0111\u1eb7t c\u1ee7a b\u1ea1n\u2014\u0111\u00f4i khi theo ngh\u0129a \u0111en.<\/p>\n<h3>C\u00e1i B\u1eaby Li\u1ec7t K\u00ea UL 67 M\u00e0 H\u1ea7u H\u1ebft C\u00e1c K\u1ef9 S\u01b0 B\u1ecf L\u1ee1<\/h3>\n<p>\u0110\u00e2y l\u00e0 n\u01a1i n\u00f3 tr\u1edf n\u00ean k\u1ef9 thu\u1eadt, v\u00e0 n\u01a1i c\u00e1c c\u00e0i \u0111\u1eb7t kh\u00f4ng v\u01b0\u1ee3t qua \u0111\u01b0\u1ee3c ki\u1ec3m tra.<\/p>\n<p>UL 67 cho ph\u00e9p hai lo\u1ea1i danh s\u00e1ch b\u1ea3ng \u0111i\u1ec7n:<\/p>\n<ol>\n<li><strong>\u201cB\u1ea3ng \u0111i\u1ec7n\u201d<\/strong> (ch\u1ec9 b\u1ea3ng, kh\u00f4ng c\u00f3 v\u1ecf b\u1ecdc)<\/li>\n<li><strong>\u201cB\u1ea3ng \u0111i\u1ec7n k\u00edn\u201d<\/strong> (b\u1ea3ng + v\u1ecf b\u1ecdc \u0111\u01b0\u1ee3c ki\u1ec3m tra nh\u01b0 m\u1ed9t c\u1ee5m ho\u00e0n ch\u1ec9nh)<\/li>\n<\/ol>\n<p>S\u1ef1 kh\u00e1c bi\u1ec7t n\u00e0y quan tr\u1ecdng v\u00ec <strong>\u0111\u1ecbnh m\u1ee9c d\u00f2ng \u0111i\u1ec7n ng\u1eafn m\u1ea1ch<\/strong>. Khi m\u1ed9t b\u1ea3ng \u0111i\u1ec7n \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea m\u00e0 kh\u00f4ng c\u00f3 v\u1ecf b\u1ecdc c\u1ee5 th\u1ec3\u2014ch\u1ec9 b\u1ea3ng tr\u1ea7n\u2014UL cung c\u1ea5p cho n\u00f3 \u0111\u1ecbnh m\u1ee9c d\u00f2ng \u0111i\u1ec7n ng\u1eafn m\u1ea1ch m\u1eb7c \u0111\u1ecbnh l\u00e0 <strong>10.000 ampe (10kA) t\u1ed1i \u0111a<\/strong>. Th\u1ebf th\u00f4i. Kh\u00f4ng quan tr\u1ecdng n\u1ebfu c\u00e1c b\u1ed9 ng\u1eaft m\u1ea1ch b\u00ean trong \u0111\u01b0\u1ee3c \u0111\u1ecbnh m\u1ee9c cho kh\u1ea3 n\u0103ng c\u1eaft 65kA ho\u1eb7c 100kA. C\u1ee5m l\u1eafp r\u00e1p gi\u1edbi h\u1ea1n \u1edf 10kA.<\/p>\n<p><strong>\u0110\u00e2y l\u00e0 \u201cC\u00e1i B\u1eaby M\u1eb7c \u0110\u1ecbnh 10kA.\u201d<\/strong><\/p>\n<p>N\u1ebfu d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 kh\u1ea3 d\u1ee5ng c\u1ee7a t\u00f2a nh\u00e0 c\u1ee7a b\u1ea1n t\u1ea1i v\u1ecb tr\u00ed b\u1ea3ng v\u01b0\u1ee3t qu\u00e1 10.000A (ph\u1ed5 bi\u1ebfn trong c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i g\u1ea7n m\u00e1y bi\u1ebfn \u00e1p ti\u1ec7n \u00edch), v\u00e0 b\u1ea1n \u0111\u00e3 c\u00e0i \u0111\u1eb7t danh s\u00e1ch ch\u1ec9 \u201cB\u1ea3ng \u0111i\u1ec7n\u201d? Vi ph\u1ea1m quy t\u1eafc. NEC 110.9 y\u00eau c\u1ea7u t\u1ea5t c\u1ea3 c\u00e1c thi\u1ebft b\u1ecb ph\u1ea3i c\u00f3 \u0111\u1ecbnh m\u1ee9c c\u1eaft <strong>\u00edt nh\u1ea5t b\u1eb1ng d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 kh\u1ea3 d\u1ee5ng t\u1ed1i \u0111a<\/strong>.<\/p>\n<p>C\u00e1c b\u1ea3ng \u0111i\u1ec7n k\u00edn\u2014nh\u1eefng b\u1ea3ng \u0111\u01b0\u1ee3c ki\u1ec3m tra v\u1edbi c\u00e1c t\u1ee7 c\u1ee5 th\u1ec3 c\u1ee7a ch\u00fang\u2014c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea cho c\u00e1c \u0111\u1ecbnh m\u1ee9c ng\u1eafn m\u1ea1ch cao h\u01a1n nhi\u1ec1u (22kA, 42kA, 65kA ho\u1eb7c h\u01a1n) v\u00ec to\u00e0n b\u1ed9 c\u1ee5m l\u1eafp r\u00e1p \u0111\u00e3 \u0111\u01b0\u1ee3c ki\u1ec3m tra nh\u01b0 m\u1ed9t h\u1ec7 th\u1ed1ng. C\u00e1c trung t\u00e2m t\u1ea3i, l\u00e0 c\u00e1c \u0111\u01a1n v\u1ecb nh\u1ecf h\u01a1n t\u1eadp trung v\u00e0o d\u00e2n d\u1ee5ng, th\u01b0\u1eddng \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea l\u00e0 b\u1ea3ng \u0111i\u1ec7n k\u00edn nh\u01b0ng hi\u1ebfm khi v\u01b0\u1ee3t qu\u00e1 \u0111\u1ecbnh m\u1ee9c 22kA.<\/p>\n<blockquote><p><strong>Pro-\u0110\u1ea7u #1:<\/strong> Tr\u01b0\u1edbc khi ch\u1ec9 \u0111\u1ecbnh b\u1ea5t k\u1ef3 b\u1ea3ng \u0111i\u1ec7n ho\u1eb7c trung t\u00e2m t\u1ea3i n\u00e0o, h\u00e3y x\u00e1c minh lo\u1ea1i danh s\u00e1ch UL. T\u00ecm \u201cB\u1ea3ng \u0111i\u1ec7n k\u00edn\u201d tr\u00ean nh\u00e3n n\u1ebfu b\u1ea1n c\u1ea7n \u0111\u1ecbnh m\u1ee9c tr\u00ean 10kA v\u00e0 lu\u00f4n t\u00ednh to\u00e1n d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 kh\u1ea3 d\u1ee5ng theo NEC 110.24(A)\u2014\u0111i\u1ec1u n\u00e0y \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u trong t\u1ea5t c\u1ea3 c\u00e1c nh\u00e0 \u1edf m\u1ed9t v\u00e0 hai gia \u0111\u00ecnh.<\/p><\/blockquote>\n<h2>V\u01b0\u1ee3t Ra Ngo\u00e0i B\u1ea3ng Th\u00f4ng S\u1ed1 K\u1ef9 Thu\u1eadt: 6 Ti\u00eau Ch\u00ed L\u1ef1a Ch\u1ecdn Th\u1ef1c T\u1ebf<\/h2>\n<p>H\u00e3y qu\u00ean c\u00e1c b\u1ea3ng so s\u00e1nh ch\u1ec9 li\u1ec7t k\u00ea \u0111i\u1ec7n \u00e1p v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n. D\u01b0\u1edbi \u0111\u00e2y l\u00e0 c\u00e1c y\u1ebfu t\u1ed1 k\u1ef9 thu\u1eadt th\u1ef1c s\u1ef1 quy\u1ebft \u0111\u1ecbnh xem vi\u1ec7c l\u1eafp \u0111\u1eb7t c\u1ee7a b\u1ea1n c\u00f3 v\u01b0\u1ee3t qua \u0111\u01b0\u1ee3c ki\u1ec3m tra v\u00e0 ph\u1ee5c v\u1ee5 t\u00f2a nh\u00e0 trong su\u1ed1t v\u00f2ng \u0111\u1eddi thi\u1ebft k\u1ebf c\u1ee7a n\u00f3 hay kh\u00f4ng.<\/p>\n<h3>1. G\u1eafn B\u1ed9 Ng\u1eaft M\u1ea1ch: S\u1ef1 Kh\u00e1c Bi\u1ec7t C\u1ee7a Bu-l\u00f4ng<\/h3>\n<p>C\u00e1c trung t\u00e2m t\u1ea3i s\u1eed d\u1ee5ng <strong>b\u1ed9 ng\u1eaft m\u1ea1ch c\u1eafm<\/strong> \u0111\u1ed9c quy\u1ec1n. B\u1ea1n g\u1eafn ch\u00fang v\u00e0o thanh c\u00e1i\u2014nhanh ch\u00f3ng, d\u1ec5 d\u00e0ng, r\u1ebb ti\u1ec1n. B\u1ea3ng \u0111i\u1ec7n cung c\u1ea5p c\u1ea3 c\u1eafm v\u00e0 <strong>b\u1ed9 ng\u1eaft m\u1ea1ch b\u1eaft v\u00edt<\/strong>.<\/p>\n<p>T\u1ea1i sao \u0111i\u1ec1u n\u00e0y l\u1ea1i quan tr\u1ecdng? <strong>Rung \u0111\u1ed9ng, c\u1ea5p ng\u01b0\u1ee3c v\u00e0 t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a k\u1ebft n\u1ed1i.<\/strong><\/p>\n<p>B\u1ed9 ng\u1eaft m\u1ea1ch c\u1eafm ho\u1ea1t \u0111\u1ed9ng t\u1ed1t trong c\u00e1c t\u1ea7ng h\u1ea7m d\u00e2n d\u1ee5ng y\u00ean t\u0129nh. Di chuy\u1ec3n b\u1ea3ng \u0111\u00f3 \u0111\u1ebfn m\u1ed9t nh\u00e0 m\u00e1y c\u00f4ng nghi\u1ec7p v\u1edbi m\u00e1y n\u00e9n l\u00e0m rung chuy\u1ec3n t\u00f2a nh\u00e0, ho\u1eb7c tri\u1ec3n khai n\u00f3 \u0111\u1ec3 c\u1ea5p ng\u01b0\u1ee3c n\u0103ng l\u01b0\u1ee3ng m\u1eb7t tr\u1eddi? V\u1ea5n \u0111\u1ec1. NEC 408.36(D) tr\u1ef1c ti\u1ebfp gi\u1ea3i quy\u1ebft r\u1ee7i ro n\u00e0y: \u201cC\u00e1c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng lo\u1ea1i c\u1eafm... \u0111\u01b0\u1ee3c c\u1ea5p ng\u01b0\u1ee3c... ph\u1ea3i \u0111\u01b0\u1ee3c c\u1ed1 \u0111\u1ecbnh t\u1ea1i ch\u1ed7 b\u1eb1ng m\u1ed9t b\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t b\u1ed5 sung y\u00eau c\u1ea7u m\u1ed9t l\u1ef1c k\u00e9o kh\u00e1c \u0111\u1ec3 nh\u1ea3 thi\u1ebft b\u1ecb.\u201d<\/p>\n<p>Ch\u00fang t\u00f4i \u0111\u00e3 th\u1ea5y c\u00e1c c\u00e0i \u0111\u1eb7t n\u01a1i c\u00e1c b\u1ed9 ng\u1eaft m\u1ea1ch n\u0103ng l\u01b0\u1ee3ng m\u1eb7t tr\u1eddi \u0111\u01b0\u1ee3c c\u1ea5p ng\u01b0\u1ee3c kh\u00f4ng \u0111\u01b0\u1ee3c c\u1ed1 \u0111\u1ecbnh \u0111\u00fang c\u00e1ch\u2014ch\u1ec9 \u0111\u01b0\u1ee3c gi\u1eef b\u1eb1ng ma s\u00e1t v\u1edbi c\u00e1c k\u1eb9p c\u1eafm ti\u00eau chu\u1ea9n. Ki\u1ec3m tra \u0111\u1ea7u ti\u00ean? Th\u1ebb \u0111\u1ecf. B\u1ed9 ng\u1eaft m\u1ea1ch c\u00f3 th\u1ec3 b\u1ecb k\u00e9o ra kh\u1ecfi thanh c\u00e1i khi \u0111ang \u0111\u01b0\u1ee3c c\u1ea5p \u0111i\u1ec7n, l\u00e0m l\u1ed9 ra \u0111i\u1ec7n \u00e1p 240V \u0111ang ho\u1ea1t \u0111\u1ed9ng <a href=\"https:\/\/test.viox.com\/vi\/busbar\/\">thanh c\u00e1i<\/a>.<\/p>\n<p>B\u1ed9 ng\u1eaft m\u1ea1ch b\u1eaft v\u00edt lo\u1ea1i b\u1ecf r\u1ee7i ro n\u00e0y. B\u1ed9 ng\u1eaft m\u1ea1ch b\u1eaft tr\u1ef1c ti\u1ebfp v\u00e0o thanh c\u00e1i b\u1eb1ng c\u00e1c b\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t c\u01a1 h\u1ecdc. K\u1ebft n\u1ed1i kh\u00f4ng th\u1ec3 rung l\u1ecfng, kh\u00f4ng th\u1ec3 v\u00f4 t\u00ecnh b\u1ecb k\u00e9o ra v\u00e0 cung c\u1ea5p kh\u1ea3 n\u0103ng mang d\u00f2ng \u0111i\u1ec7n v\u01b0\u1ee3t tr\u1ed9i cho c\u00e1c m\u1ea1ch c\u00f3 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n cao. \u0110\u00e2y l\u00e0 l\u00fd do t\u1ea1i sao b\u1ea3ng \u0111i\u1ec7n\u2014\u0111\u1eb7c bi\u1ec7t l\u00e0 nh\u1eefng b\u1ea3ng \u0111\u01b0\u1ee3c \u0111\u1ecbnh m\u1ee9c tr\u00ean 225A\u2014ng\u00e0y c\u00e0ng s\u1eed d\u1ee5ng c\u1ea5u tr\u00fac b\u1eaft v\u00edt.<\/p>\n<blockquote><p><strong>Pro-\u0110\u1ea7u #2:<\/strong> \u0110\u1ed1i v\u1edbi b\u1ea5t k\u1ef3 \u1ee9ng d\u1ee5ng c\u1ea5p ng\u01b0\u1ee3c n\u00e0o (n\u0103ng l\u01b0\u1ee3ng m\u1eb7t tr\u1eddi, m\u00e1y ph\u00e1t \u0111i\u1ec7n, l\u01b0u tr\u1eef n\u0103ng l\u01b0\u1ee3ng), h\u00e3y x\u00e1c minh s\u1ef1 tu\u00e2n th\u1ee7 NEC 408.36(D). N\u1ebfu s\u1eed d\u1ee5ng b\u1ed9 ng\u1eaft m\u1ea1ch c\u1eafm, th\u00ec \u201cb\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t b\u1ed5 sung\u201d th\u01b0\u1eddng c\u00f3 ngh\u0129a l\u00e0 m\u1ed9t b\u1ed9 gi\u1eef c\u1ee5 th\u1ec3 t\u1eeb nh\u00e0 s\u1ea3n xu\u1ea5t. N\u1ebfu thanh tra kh\u00f4ng nh\u00ecn th\u1ea5y n\u00f3, b\u1ea1n s\u1ebd b\u1ecb g\u1eafn th\u1ebb.<\/p><\/blockquote>\n<h3>2. \u0110i\u1ec7n \u00c1p &amp; Pha: \u0110\u01b0\u1eddng Ph\u00e2n Chia Ba Pha<\/h3>\n<p>\u0110\u00e2y l\u00e0 \u0111i\u1ec3m d\u1eebng c\u1ee9ng r\u00f5 r\u00e0ng nh\u1ea5t gi\u1eefa trung t\u00e2m t\u1ea3i v\u00e0 b\u1ea3ng \u0111i\u1ec7n.<\/p>\n<p><strong>Trung t\u00e2m t\u1ea3i:<\/strong> T\u1ed1i \u0111a 240 volt, ch\u1ec9 m\u1ed9t pha.<\/p>\n<p><strong>B\u1ea3ng \u0111i\u1ec7n:<\/strong> L\u00ean \u0111\u1ebfn 600 volt (ho\u1eb7c cao h\u01a1n v\u1edbi c\u00e1c thi\u1ebft k\u1ebf \u0111\u1eb7c bi\u1ec7t), m\u1ed9t pha ho\u1eb7c ba pha.<\/p>\n<p>N\u1ebfu t\u00ednh to\u00e1n t\u1ea3i c\u1ee7a b\u1ea1n bao g\u1ed3m b\u1ea5t k\u1ef3 thi\u1ebft b\u1ecb ba pha n\u00e0o\u2014HVAC th\u01b0\u01a1ng m\u1ea1i, m\u00e1y c\u00f4ng c\u1ee5, \u0111\u1ed9ng c\u01a1 l\u1edbn, PDU trung t\u00e2m d\u1eef li\u1ec7u\u2014t\u00f9y ch\u1ecdn trung t\u00e2m t\u1ea3i v\u1eeba bi\u1ebfn m\u1ea5t. B\u1ea1n c\u1ea7n m\u1ed9t b\u1ea3ng \u0111i\u1ec7n. Kh\u00f4ng c\u00f3 c\u00e1ch n\u00e0o kh\u00e1c.<\/p>\n<p>Ngay c\u1ea3 trong c\u00e1c \u1ee9ng d\u1ee5ng m\u1ed9t pha, \u0111i\u1ec7n \u00e1p v\u1eabn quan tr\u1ecdng. M\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i 208Y\/120V (ph\u1ed5 bi\u1ebfn trong c\u00e1c kh\u00f4ng gian \u0111a ng\u01b0\u1eddi thu\u00ea \u0111\u01b0\u1ee3c cung c\u1ea5p t\u1eeb d\u1ecbch v\u1ee5 ti\u1ec7n \u00edch ba pha) y\u00eau c\u1ea7u m\u1ed9t b\u1ea3ng \u0111i\u1ec7n, kh\u00f4ng ph\u1ea3i trung t\u00e2m t\u1ea3i 120\/240V. Ch\u00fang kh\u00f4ng t\u01b0\u01a1ng th\u00edch v\u1ec1 \u0111i\u1ec7n.<\/p>\n<h3>3. Tr\u1ea7n C\u01b0\u1eddng \u0110\u1ed9 D\u00f2ng \u0110i\u1ec7n: N\u01a1i C\u00e1c Trung T\u00e2m T\u1ea3i D\u1eebng L\u1ea1i<\/h3>\n<p>C\u00e1c trung t\u00e2m t\u1ea3i \u0111\u1ea1t t\u1ed1i \u0111a \u1edf <strong>400 ampe<\/strong>. H\u1ea7u h\u1ebft l\u00e0 200A ho\u1eb7c \u00edt h\u01a1n.<\/p>\n<p>B\u1ea3ng \u0111i\u1ec7n m\u1edf r\u1ed9ng t\u1eeb 100A \u0111\u1ebfn <strong>1.200A<\/strong> (v\u1edbi b\u1ea3ng chuy\u1ec3n m\u1ea1ch \u0111\u1ea3m nh\u1eadn \u1edf tr\u00ean m\u1ee9c \u0111\u00f3).<\/p>\n<p>\u0110\u00e2y l\u00e0 c\u00e1i b\u1eaby: \u0111\u1ecbnh m\u1ee9c trung t\u00e2m t\u1ea3i 400A \u0111\u00f3 l\u00e0 <strong>\u0111\u1ecbnh m\u1ee9c thanh c\u00e1i<\/strong>, kh\u00f4ng ph\u1ea3i c\u00f4ng su\u1ea5t s\u1eed d\u1ee5ng \u0111\u01b0\u1ee3c c\u1ee7a b\u1ea1n. NEC 215.2(A) y\u00eau c\u1ea7u c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n c\u1ee7a b\u1ed9 c\u1ea5p li\u1ec7u \u201ckh\u00f4ng \u0111\u01b0\u1ee3c nh\u1ecf h\u01a1n t\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c c\u1ed9ng v\u1edbi 125 ph\u1ea7n tr\u0103m t\u1ea3i li\u00ean t\u1ee5c.\u201d NEC 408.36 y\u00eau c\u1ea7u thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng b\u1ea3o v\u1ec7 b\u1ea3ng \u0111i\u1ec7n kh\u00f4ng \u0111\u01b0\u1ee3c v\u01b0\u1ee3t qu\u00e1 \u0111\u1ecbnh m\u1ee9c c\u1ee7a b\u1ea3ng \u0111i\u1ec7n.<\/p>\n<p>V\u00ec v\u1eady, n\u1ebfu b\u1ea1n c\u00f3 m\u1ed9t <strong>t\u1ea3i li\u00ean t\u1ee5c 300A<\/strong> (ph\u1ed5 bi\u1ebfn trong c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i c\u00f3 h\u1ec7 th\u1ed1ng chi\u1ebfu s\u00e1ng v\u00e0 HVAC 24\/7), t\u00ednh to\u00e1n t\u1ed1i thi\u1ec3u c\u1ee7a b\u1ea1n l\u00e0:<\/p>\n<p><strong>300A \u00d7 125% = 375A k\u00edch th\u01b0\u1edbc t\u1ed1i thi\u1ec3u c\u1ee7a b\u1ed9 c\u1ea5p ngu\u1ed3n\/c\u1ea7u dao<\/strong><\/p>\n<p>C\u1ea7u dao ch\u00ednh c\u1ee7a trung t\u00e2m t\u1ea3i 400A c\u1ee7a b\u1ea1n c\u1ea7n ph\u1ea3i l\u00e0 375A ho\u1eb7c 400A. Nh\u01b0ng \u0111\u00e2y l\u00e0 v\u1ea5n \u0111\u1ec1: n\u1ebfu b\u1ea1n s\u1eed d\u1ee5ng c\u1ea7u dao ch\u00ednh 400A tr\u00ean m\u1ed9t thanh c\u00e1i 400A, b\u1ea1n \u0111\u00e3 s\u1eed d\u1ee5ng h\u1ebft c\u00f4ng su\u1ea5t \u0111\u1ecbnh m\u1ee9c c\u1ee7a m\u00ecnh ch\u1ec9 \u0111\u1ec3 b\u1ea3o v\u1ec7 t\u1ea3i li\u00ean t\u1ee5c m\u1ed9t c\u00e1ch th\u00edch h\u1ee3p. Th\u00eam <strong>b\u1ea5t k\u1ef3<\/strong> t\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c, v\u00e0 b\u1ea1n \u0111ang v\u01b0\u1ee3t qu\u00e1 c\u00f4ng su\u1ea5t.<\/p>\n<p>Gi\u1ea3i ph\u00e1p \u0111\u00fang? Ch\u1ec9 \u0111\u1ecbnh m\u1ed9t b\u1ea3ng \u0111i\u1ec7n v\u1edbi \u0111\u1ecbnh m\u1ee9c thanh c\u00e1i 600A ho\u1eb7c 800A. Sau \u0111\u00f3, b\u1ea1n c\u00f3 ch\u1ed7 cho c\u1ea3 c\u1ea7u dao ch\u00ednh 375-400A <strong>v\u00e0<\/strong> v\u00e0 s\u1ef1 ph\u00e1t tri\u1ec3n trong t\u01b0\u01a1ng lai.<\/p>\n<p>\u0110i\u1ec1u n\u00e0y d\u1eabn tr\u1ef1c ti\u1ebfp \u0111\u1ebfn kh\u00e1i ni\u1ec7m ti\u1ebfp theo c\u1ee7a ch\u00fang ta\u2026<\/p>\n<h3>4. Kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng: V\u1ea5n \u0111\u1ec1 \u0110\u1ea7y T\u1ea3i Sau 2 N\u0103m<\/h3>\n<p>Trung t\u00e2m t\u1ea3i c\u00f3 <strong>c\u00f4ng su\u1ea5t c\u1ed1 \u0111\u1ecbnh<\/strong>. S\u1ed1 l\u01b0\u1ee3ng v\u1ecb tr\u00ed l\u00e0 nh\u1eefng g\u00ec b\u1ea1n mua\u2014th\u01b0\u1eddng l\u00e0 12, 20, 24, 30 ho\u1eb7c 40 v\u1ecb tr\u00ed. M\u1ed9t khi n\u00f3 \u0111\u00e3 \u0111\u1ea7y, n\u00f3 \u0111\u00e3 \u0111\u1ea7y. L\u1ef1a ch\u1ecdn duy nh\u1ea5t c\u1ee7a b\u1ea1n l\u00e0 m\u1ed9t b\u1ea3ng \u0111i\u1ec7n ph\u1ee5 ho\u1eb7c thay th\u1ebf ho\u00e0n to\u00e0n.<\/p>\n<p>B\u1ea3ng \u0111i\u1ec7n l\u00e0 <strong>d\u1ea1ng m\u00f4-\u0111un<\/strong>. Nhi\u1ec1u b\u1ea3ng \u0111i\u1ec7n th\u01b0\u01a1ng m\u1ea1i c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c m\u1edf r\u1ed9ng v\u1edbi c\u00e1c ph\u1ea7n b\u1ed5 sung, ho\u1eb7c \u0111\u01b0\u1ee3c thi\u1ebft k\u1ebf ngay t\u1eeb \u0111\u1ea7u v\u1edbi kh\u00f4ng gian cho c\u00e1c c\u1ea7u dao trong t\u01b0\u01a1ng lai.<\/p>\n<p>\u0110\u00e2y l\u00e0 k\u1ecbch b\u1ea3n ch\u00fang ta th\u1ea5y li\u00ean t\u1ee5c: M\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i nh\u1ecf b\u1eaft \u0111\u1ea7u v\u1edbi m\u1ed9t trung t\u00e2m t\u1ea3i 200A, 30 v\u1ecb tr\u00ed. C\u00f3 v\u1ebb h\u1ee3p l\u00fd\u201410 m\u1ea1ch cho chi\u1ebfu s\u00e1ng, 8 cho \u1ed5 c\u1eafm, 5 cho HVAC, 3 cho thi\u1ebft b\u1ecb kh\u00e1c. \u0110\u00f3 l\u00e0 26 m\u1ea1ch, \u0111\u1ec3 l\u1ea1i 4 v\u1ecb tr\u00ed cho vi\u1ec7c m\u1edf r\u1ed9ng trong t\u01b0\u01a1ng lai. Tuy\u1ec7t v\u1eddi, ph\u1ea3i kh\u00f4ng?<\/p>\n<p>N\u0103m 2: Ng\u01b0\u1eddi thu\u00ea mu\u1ed1n th\u00eam m\u1ed9t ph\u00f2ng m\u00e1y ch\u1ee7 (2 m\u1ea1ch chuy\u00ean d\u1ee5ng), HVAC \u0111\u01b0\u1ee3c n\u00e2ng c\u1ea5p (3 m\u1ea1ch) v\u00e0 tr\u1ea1m s\u1ea1c EV (1 m\u1ea1ch). \u0110\u00f3 l\u00e0 6 m\u1ea1ch m\u1edbi. B\u1ea1n ch\u1ec9 c\u00f2n 4 v\u1ecb tr\u00ed.<\/p>\n<p>N\u0103m 3: Ng\u01b0\u1eddi thu\u00ea kh\u00e1c chuy\u1ec3n \u0111\u1ebfn, c\u1ea7n thi\u1ebft b\u1ecb nh\u00e0 b\u1ebfp th\u01b0\u01a1ng m\u1ea1i (5 m\u1ea1ch), h\u1ec7 th\u1ed1ng chi\u1ebfu s\u00e1ng \u0111\u01b0\u1ee3c n\u00e2ng c\u1ea5p v\u1edbi c\u00e1c b\u1ea3ng \u0111i\u1ec1u ch\u1ec9nh \u0111\u1ed9 s\u00e1ng (4 m\u1ea1ch).<\/p>\n<p>Tr\u00f2 ch\u01a1i k\u1ebft th\u00fac. <strong>V\u1ea5n \u0111\u1ec1 \u0110\u1ea7y T\u1ea3i Sau 2 N\u0103m<\/strong> l\u1ea1i x\u1ea3y ra.<\/p>\n<p>B\u00e2y gi\u1edd b\u1ea1n \u0111ang \u0111\u1ecbnh gi\u00e1 vi\u1ec7c thay th\u1ebf b\u1ea3ng \u0111i\u1ec7n ho\u00e0n ch\u1ec9nh ($3,500 cho v\u1eadt li\u1ec7u), c\u1ed9ng v\u1edbi chi ph\u00ed nh\u00e2n c\u00f4ng l\u1eafp \u0111\u1eb7t (8-12 gi\u1edd v\u1edbi gi\u00e1 $125-150\/gi\u1edd = $1,000-1,800), c\u1ed9ng v\u1edbi vi\u1ec7c \u0111i\u1ec1u ph\u1ed1i th\u1eddi gian ng\u1eebng ho\u1ea1t \u0111\u1ed9ng v\u1edbi t\u1ea5t c\u1ea3 ng\u01b0\u1eddi thu\u00ea, c\u1ed9ng v\u1edbi ph\u00ed gi\u1ea5y ph\u00e9p v\u00e0 ki\u1ec3m tra, c\u1ed9ng v\u1edbi chi ph\u00ed l\u00e0m th\u1ea5t v\u1ecdng m\u1ed9t ng\u01b0\u1eddi thu\u00ea ph\u1ea3i ch\u1edd \u0111\u1ee3i c\u00f4ng su\u1ea5t \u0111i\u1ec7n.<\/p>\n<p>T\u1ed5ng chi ph\u00ed c\u1ee7a quy\u1ebft \u0111\u1ecbnh trung t\u00e2m t\u1ea3i \u201cth\u00e2n thi\u1ec7n v\u1edbi ng\u00e2n s\u00e1ch\u201d: <strong>$5,000-7,000<\/strong> chi ph\u00ed thay th\u1ebf trong v\u00f2ng 3 n\u0103m, so v\u1edbi vi\u1ec7c chi th\u00eam $800-1,200 tr\u1ea3 tr\u01b0\u1edbc cho m\u1ed9t b\u1ea3ng \u0111i\u1ec7n c\u00f3 k\u00edch th\u01b0\u1edbc ph\u00f9 h\u1ee3p v\u1edbi kh\u1ea3 n\u0103ng m\u1edf r\u1ed9ng.<\/p>\n<blockquote><p><strong>M\u1eb9o chuy\u00ean nghi\u1ec7p #3: Quy t\u1eafc T\u0103ng tr\u01b0\u1edfng 125%<\/strong> (kh\u00f4ng c\u00f3 trong NEC, nh\u01b0ng \u0111\u00e3 \u0111\u01b0\u1ee3c ki\u1ec3m ch\u1ee9ng): T\u00ednh s\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch ban \u0111\u1ea7u c\u1ee7a b\u1ea1n, nh\u00e2n v\u1edbi 1.25 v\u00e0 ch\u1ec9 \u0111\u1ecbnh s\u1ed1 l\u01b0\u1ee3ng v\u1ecb tr\u00ed t\u1ed1i thi\u1ec3u \u0111\u00f3. \u0110\u1ed1i v\u1edbi c\u00e1c \u1ee9ng d\u1ee5ng th\u01b0\u01a1ng m\u1ea1i v\u1edbi d\u1ef1 ki\u1ebfn \u200b\u200bthay \u0111\u1ed5i ng\u01b0\u1eddi thu\u00ea, h\u00e3y s\u1eed d\u1ee5ng 1.5 \u00d7 s\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch ban \u0111\u1ea7u. C\u00f3, b\u1ea1n s\u1ebd c\u00f3 c\u00e1c v\u1ecb tr\u00ed tr\u1ed1ng ban \u0111\u1ea7u. \u0110\u00f3 l\u00e0 m\u1ee5c \u0111\u00edch.<\/p><\/blockquote>\n<h3>5. Ki\u1ec3m tra Th\u1ef1c t\u1ebf v\u1ec1 \u0110\u1ecbnh m\u1ee9c Ng\u1eafn M\u1ea1ch<\/h3>\n<p>Ch\u00fang ta \u0111\u00e3 \u0111\u1ec1 c\u1eadp \u0111\u1ebfn c\u00e1i b\u1eaby m\u1eb7c \u0111\u1ecbnh 10kA tr\u01b0\u1edbc \u0111\u00f3, nh\u01b0ng h\u00e3y n\u00f3i c\u1ee5 th\u1ec3 v\u1ec1 l\u00fd do t\u1ea1i sao n\u00f3 l\u1ea1i quan tr\u1ecdng.<\/p>\n<p>NEC 110.24(A) y\u00eau c\u1ea7u t\u1ea5t c\u1ea3 c\u00e1c c\u00e0i \u0111\u1eb7t c\u00f4ng nghi\u1ec7p v\u00e0 th\u01b0\u01a1ng m\u1ea1i (kh\u00f4ng ph\u1ea3i nh\u00e0 \u1edf m\u1ed9t v\u00e0 hai gia \u0111\u00ecnh) ph\u1ea3i c\u00f3 d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 t\u1ed1i \u0111a c\u00f3 s\u1eb5n \u0111\u01b0\u1ee3c t\u00ednh to\u00e1n v\u00e0 <strong>\u0111\u00e1nh d\u1ea5u v\u0129nh vi\u1ec5n<\/strong> tr\u00ean thi\u1ebft b\u1ecb d\u1ecbch v\u1ee5 v\u00e0 b\u1ea3ng \u0111i\u1ec7n ph\u00e2n ph\u1ed1i. Ng\u00e0y t\u00ednh to\u00e1n ph\u1ea3i \u0111\u01b0\u1ee3c bao g\u1ed3m.<\/p>\n<p>Thanh tra c\u1ee7a b\u1ea1n s\u1ebd ki\u1ec3m tra ba \u0111i\u1ec1u:<\/p>\n<ol>\n<li>D\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u tr\u00ean thi\u1ebft b\u1ecb kh\u00f4ng? (N\u1ebfu kh\u00f4ng, h\u00e3y g\u1eafn th\u1ebb #1)<\/li>\n<li>\u0110\u1ecbnh m\u1ee9c ng\u1eafn m\u1ea1ch c\u1ee7a b\u1ea3ng \u0111i\u1ec7n c\u00f3 v\u01b0\u1ee3t qu\u00e1 d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u kh\u00f4ng? (N\u1ebfu kh\u00f4ng, h\u00e3y g\u1eafn th\u1ebb #2)<\/li>\n<li>T\u1ea5t c\u1ea3 c\u00e1c c\u1ea7u dao b\u00ean trong c\u00f3 \u0111\u1ecbnh m\u1ee9c ng\u1eaft \u00edt nh\u1ea5t b\u1eb1ng d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n kh\u00f4ng? (N\u1ebfu kh\u00f4ng, h\u00e3y g\u1eafn th\u1ebb #3)<\/li>\n<\/ol>\n<p>Trung t\u00e2m t\u1ea3i, v\u1edbi \u0111\u1ecbnh m\u1ee9c 10kA ho\u1eb7c 22kA \u0111i\u1ec3n h\u00ecnh c\u1ee7a ch\u00fang, kh\u00f4ng v\u01b0\u1ee3t qua b\u00e0i ki\u1ec3m tra n\u00e0y trong nhi\u1ec1u t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i. M\u1ed9t d\u1ecbch v\u1ee5 3,000A n\u1eb1m c\u00e1ch m\u00e1y bi\u1ebfn \u00e1p 1,500 kVA 50 feet c\u00f3 th\u1ec3 d\u1ec5 d\u00e0ng c\u00f3 d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n 35-50kA t\u1ea1i c\u00e1c b\u1ea3ng ph\u00e2n ph\u1ed1i. Trung t\u00e2m t\u1ea3i 22kA c\u1ee7a b\u1ea1n v\u1eeba tr\u1edf th\u00e0nh m\u1ed9t vi ph\u1ea1m quy t\u1eafc.<\/p>\n<p>B\u1ea3ng \u0111i\u1ec7n \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh cho m\u1ee5c \u0111\u00edch s\u1eed d\u1ee5ng th\u01b0\u01a1ng m\u1ea1i th\u01b0\u1eddng mang \u0111\u1ecbnh m\u1ee9c ng\u1eafn m\u1ea1ch 42kA, 65kA ho\u1eb7c 100kA\u2014ph\u00f9 h\u1ee3p v\u1edbi m\u1ee9c d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 th\u1ef1c t\u1ebf c\u1ee7a t\u00f2a nh\u00e0.<\/p>\n<h3>6. M\u00f4i tr\u01b0\u1eddng &amp; \u1ee8ng d\u1ee5ng: \u0110\u1ecbnh m\u1ee9c NEMA v\u00e0 C\u00e1c \u0110i\u1ec1u ki\u1ec7n \u0110\u1eb7c bi\u1ec7t<\/h3>\n<p>Trung t\u00e2m t\u1ea3i: NEMA Lo\u1ea1i 1 (trong nh\u00e0, \u0111\u1ecba \u0111i\u1ec3m kh\u00f4 r\u00e1o) v\u1edbi c\u00e1c t\u00f9y ch\u1ecdn Lo\u1ea1i 3R (ngo\u00e0i tr\u1eddi, ch\u1ed1ng ch\u1ecbu th\u1eddi ti\u1ebft) kh\u00f4ng th\u01b0\u1eddng xuy\u00ean.<\/p>\n<p>B\u1ea3ng \u0111i\u1ec7n: C\u00f3 s\u1eb5n trong t\u1ea5t c\u1ea3 c\u00e1c lo\u1ea1i NEMA bao g\u1ed3m Lo\u1ea1i 3R, 4, 4X, 12 (c\u00f4ng nghi\u1ec7p) v\u00e0 \u0111\u1ecbnh m\u1ee9c v\u1ecb tr\u00ed nguy hi\u1ec3m (Lo\u1ea1i I Div 1\/2, Lo\u1ea1i II, v.v.).<\/p>\n<p>N\u1ebfu \u1ee9ng d\u1ee5ng c\u1ee7a b\u1ea1n li\u00ean quan \u0111\u1ebfn:<\/p>\n<ul>\n<li>L\u1eafp \u0111\u1eb7t ngo\u00e0i tr\u1eddi \u2192 B\u1ea1n c\u1ea7n NEMA 3R t\u1ed1i thi\u1ec3u<\/li>\n<li>Khu v\u1ef1c r\u1eeda tr\u00f4i\/ch\u1ebf bi\u1ebfn th\u1ef1c ph\u1ea9m \u2192 NEMA 4X (kh\u00f4ng g\u1ec9)<\/li>\n<li>C\u00f4ng nghi\u1ec7p b\u1ee5i b\u1eb7m \u2192 NEMA 12<\/li>\n<li>H\u00f3a ch\u1ea5t\/h\u00f3a d\u1ea7u \u2192 B\u1ea3ng \u0111i\u1ec7n \u0111\u01b0\u1ee3c x\u1ebfp h\u1ea1ng v\u1ecb tr\u00ed nguy hi\u1ec3m<\/li>\n<\/ul>\n<p>Trung t\u00e2m t\u1ea3i kh\u00f4ng \u0111\u01b0\u1ee3c s\u1ea3n xu\u1ea5t cho c\u00e1c \u0111i\u1ec1u ki\u1ec7n n\u00e0y. B\u1ea3ng \u0111i\u1ec7n th\u00ec c\u00f3.<\/p>\n<p>Ngo\u00e0i ra, NEC 408.43 c\u1ea5m l\u1eafp \u0111\u1eb7t b\u1ea3ng \u0111i\u1ec7n \u1edf v\u1ecb tr\u00ed \u201c\u00fap m\u1eb7t ho\u1eb7c \u00fap l\u01b0ng\u201d (n\u1eb1m ngang v\u1edbi m\u1eb7t tr\u01b0\u1edbc h\u01b0\u1edbng l\u00ean\/xu\u1ed1ng). Ch\u00fang ph\u1ea3i th\u1eb3ng \u0111\u1ee9ng ho\u1eb7c n\u1eb1m ngang v\u1edbi m\u1eb7t tr\u01b0\u1edbc h\u01b0\u1edbng v\u00e0o t\u01b0\u1eddng. \u0110i\u1ec1u n\u00e0y \u00e1p d\u1ee5ng cho c\u1ea3 trung t\u00e2m t\u1ea3i v\u00e0 b\u1ea3ng \u0111i\u1ec7n m\u1ed9t c\u00e1ch b\u00ecnh \u0111\u1eb3ng\u2014ch\u00fang t\u00f4i \u0111\u1ec1 c\u1eadp \u0111\u1ebfn n\u00f3 v\u00ec \u0111\u00f3 l\u00e0 m\u1ed9t vi ph\u1ea1m ph\u1ed5 bi\u1ebfn khi kh\u00f4ng gian ch\u1eadt h\u1eb9p v\u00e0 ng\u01b0\u1eddi l\u1eafp \u0111\u1eb7t s\u00e1ng t\u1ea1o v\u1edbi c\u00e1c g\u00f3c l\u1eafp.<\/p>\n<blockquote><p><strong>Pro-\u0110\u1ea7u #4:<\/strong> Lu\u00f4n x\u00e1c minh \u0111\u1ecbnh m\u1ee9c NEMA ph\u00f9 h\u1ee3p v\u1edbi v\u1ecb tr\u00ed l\u1eafp \u0111\u1eb7t tr\u01b0\u1edbc khi mua s\u1eafm. Ch\u00fang t\u00f4i \u0111\u00e3 th\u1ea5y c\u00e1c trung t\u00e2m t\u1ea3i kh\u00f4ng ch\u1ed1ng ch\u1ecbu th\u1eddi ti\u1ebft \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t ngo\u00e0i tr\u1eddi v\u00ec \u201cn\u00f3 \u1edf d\u01b0\u1edbi m\u1ed9t m\u00e1i hi\u00ean.\u201d M\u00e1i hi\u00ean \u0111\u00f3 kh\u00f4ng ng\u0103n \u0111\u01b0\u1ee3c m\u01b0a ho\u1eb7c s\u1ef1 ng\u01b0ng t\u1ee5 do gi\u00f3 th\u1ed5i. Thanh tra s\u1ebd kh\u00f4ng quan t\u00e2m \u0111\u1ebfn m\u00e1i hi\u00ean c\u1ee7a b\u1ea1n.<\/p><\/blockquote>\n<h2>C\u00e1ch \u0110\u1ecbnh c\u1ee1 \u0111\u1ec3 Tu\u00e2n th\u1ee7 (V\u00e0 Tr\u00e1nh B\u1ecb G\u1eafn Th\u1ebb \u0110\u1ecf)<\/h2>\n<p>\u0110\u00e2y l\u00e0 ph\u01b0\u01a1ng ph\u00e1p ti\u1ebfp c\u1eadn c\u00f3 h\u1ec7 th\u1ed1ng v\u01b0\u1ee3t qua ki\u1ec3m tra ngay l\u1ea7n \u0111\u1ea7u ti\u00ean.<\/p>\n<h3>B\u01b0\u1edbc 1: T\u00ednh T\u1ea3i Th\u1ef1c T\u1ebf C\u1ee7a B\u1ea1n (Quy T\u1eafc 125% \u0110\u01b0\u1ee3c \u00c1p D\u1ee5ng Ch\u00ednh X\u00e1c)<\/h3>\n<p>H\u1ea7u h\u1ebft c\u00e1c k\u1ef9 s\u01b0 \u0111\u1ec1u bi\u1ebft v\u1ec1 h\u1ec7 s\u1ed1 nh\u00e2n 125% cho t\u1ea3i li\u00ean t\u1ee5c khi \u0111\u1ecbnh c\u1ee1 d\u00e2y d\u1eabn (NEC 210.19, 215.2). \u0110i\u1ec1u h\u1ecd b\u1ecf l\u1ee1 l\u00e0 <strong>h\u1ec7 s\u1ed1 nh\u00e2n t\u01b0\u01a1ng t\u1ef1 n\u00e0y \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn vi\u1ec7c l\u1ef1a ch\u1ecdn b\u1ea3ng \u0111i\u1ec7n<\/strong> th\u00f4ng qua s\u1ef1 li\u00ean k\u1ebft gi\u1eefa NEC 215.3 v\u00e0 408.36.<\/p>\n<p><strong>NEC 215.2(A)(1)<\/strong> quy \u0111\u1ecbnh: \u201c\u0110\u1ed9 d\u1eabn \u0111i\u1ec7n c\u1ee7a d\u00e2y d\u1eabn b\u1ed9 c\u1ea5p ngu\u1ed3n...kh\u00f4ng \u0111\u01b0\u1ee3c nh\u1ecf h\u01a1n t\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c c\u1ed9ng v\u1edbi 125 ph\u1ea7n tr\u0103m t\u1ea3i li\u00ean t\u1ee5c.\u201d<\/p>\n<p><strong>NEC 408.36<\/strong> quy \u0111\u1ecbnh: \u201cM\u1ed7i b\u1ea3ng \u0111i\u1ec7n ph\u1ea3i \u0111\u01b0\u1ee3c b\u1ea3o v\u1ec7 b\u1edfi m\u1ed9t thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng...\u0110\u1ecbnh m\u1ee9c kh\u00f4ng \u0111\u01b0\u1ee3c l\u1edbn h\u01a1n \u0111\u1ecbnh m\u1ee9c c\u1ee7a b\u1ea3ng \u0111i\u1ec7n.\u201d<\/p>\n<p>\u0110\u00e2y l\u00e0 c\u00e1ch ch\u00fang k\u1ebft n\u1ed1i: D\u00e2y d\u1eabn b\u1ed9 c\u1ea5p ngu\u1ed3n c\u1ee7a b\u1ea1n \u0111\u01b0\u1ee3c \u0111\u1ecbnh c\u1ee1 \u1edf m\u1ee9c 125% t\u1ea3i li\u00ean t\u1ee5c. C\u00e1c d\u00e2y d\u1eabn \u0111\u00f3 ph\u1ea3i \u0111\u01b0\u1ee3c b\u1ea3o v\u1ec7 b\u1edfi m\u1ed9t OCPD (c\u1ea7u dao ch\u00ednh). OCPD \u0111\u00f3 kh\u00f4ng \u0111\u01b0\u1ee3c v\u01b0\u1ee3t qu\u00e1 \u0111\u1ecbnh m\u1ee9c c\u1ee7a b\u1ea3ng \u0111i\u1ec7n. V\u00ec v\u1eady, <strong>thanh c\u00e1i b\u1ea3ng \u0111i\u1ec7n c\u1ee7a b\u1ea1n ph\u1ea3i ch\u1ee9a t\u1ea3i \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh 125%<\/strong>, kh\u00f4ng ch\u1ec9 t\u1ea3i \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i th\u1ef1c t\u1ebf.<\/p>\n<p><strong>T\u1ea3i li\u00ean t\u1ee5c<\/strong> \u0111\u01b0\u1ee3c \u0111\u1ecbnh ngh\u0129a trong NEC \u0110i\u1ec1u 100: \u201cM\u1ed9t t\u1ea3i m\u00e0 d\u00f2ng \u0111i\u1ec7n t\u1ed1i \u0111a d\u1ef1 ki\u1ebfn \u200b\u200bs\u1ebd ti\u1ebfp t\u1ee5c trong <strong>ba gi\u1edd tr\u1edf l\u00ean<\/strong>.\u201d \u0110i\u1ec1u n\u00e0y bao g\u1ed3m:<\/p>\n<ul>\n<li>Chi\u1ebfu s\u00e1ng trong c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i (ho\u1ea1t \u0111\u1ed9ng c\u1ea3 ng\u00e0y)<\/li>\n<li>H\u1ec7 th\u1ed1ng HVAC trong c\u00e1c kh\u00f4ng gian c\u00f3 ng\u01b0\u1eddi \u1edf li\u00ean t\u1ee5c<\/li>\n<li>Thi\u1ebft b\u1ecb l\u00e0m l\u1ea1nh<\/li>\n<li>S\u1ea1c xe \u0111i\u1ec7n (NEC 625.42 y\u00eau c\u1ea7u r\u00f5 r\u00e0ng vi\u1ec7c x\u1eed l\u00fd t\u1ea3i li\u00ean t\u1ee5c)<\/li>\n<li>T\u1ea3i m\u00e1y ch\u1ee7\/d\u1eef li\u1ec7u<\/li>\n<\/ul>\n<p><strong>T\u00ednh to\u00e1n:<\/strong><\/p>\n<p>Gi\u1ea3 s\u1eed b\u1ea1n c\u00f3:<\/p>\n<ul>\n<li>T\u1ea3i li\u00ean t\u1ee5c: 180A (chi\u1ebfu s\u00e1ng + HVAC)<\/li>\n<li>T\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c: 85A (\u1ed5 c\u1eafm, thi\u1ebft b\u1ecb kh\u00f4ng th\u01b0\u1eddng xuy\u00ean)<\/li>\n<\/ul>\n<p><strong>T\u00ednh to\u00e1n t\u1ed1i thi\u1ec3u cho feeder\/panelboard:<\/strong><\/p>\n<ul>\n<li>(180A \u00d7 125%) + (85A \u00d7 100%) = 225A + 85A = <strong>310A t\u1ed1i thi\u1ec3u<\/strong><\/li>\n<\/ul>\n<p>B\u1ea1n c\u1ea7n m\u1ed9t panelboard v\u1edbi \u00edt nh\u1ea5t <strong>\u0110\u1ecbnh m\u1ee9c 350A ho\u1eb7c 400A<\/strong> (k\u00edch th\u01b0\u1edbc ti\u00eau chu\u1ea9n ti\u1ebfp theo theo NEC 240.6). M\u1ed9t trung t\u00e2m t\u1ea3i 200A kh\u00f4ng \u0111\u00e1p \u1ee9ng y\u00eau c\u1ea7u n\u00e0y ngay c\u1ea3 tr\u01b0\u1edbc khi b\u1ea1n n\u00f3i v\u1ec1 vi\u1ec7c m\u1edf r\u1ed9ng trong t\u01b0\u01a1ng lai.<\/p>\n<p><strong>Ngo\u1ea1i l\u1ec7:<\/strong> N\u1ebfu b\u1ea1n \u0111ang s\u1eed d\u1ee5ng c\u00e1c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng \u0111\u1ecbnh m\u1ee9c 100% (hi\u1ebfm, \u0111\u1eaft ti\u1ec1n, \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea r\u00f5 r\u00e0ng cho ho\u1ea1t \u0111\u1ed9ng li\u00ean t\u1ee5c \u1edf \u0111\u1ecbnh m\u1ee9c \u0111\u1ea7y \u0111\u1ee7), b\u1ea1n c\u00f3 th\u1ec3 \u0111\u1ecbnh c\u1ee1 \u1edf m\u1ee9c 100% t\u1ea3i li\u00ean t\u1ee5c. Nh\u01b0ng h\u00e3y ki\u1ec3m tra NEC 210.19(A)(1) Ngo\u1ea1i l\u1ec7 v\u00e0 215.2(A)(1) Ngo\u1ea1i l\u1ec7 s\u1ed1 1\u2014\u0111i\u1ec1u n\u00e0y y\u00eau c\u1ea7u to\u00e0n b\u1ed9 c\u1ee5m (panel + breaker) ph\u1ea3i \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea cho ho\u1ea1t \u0111\u1ed9ng 100%. Trung t\u00e2m t\u1ea3i trung b\u00ecnh c\u1ee7a b\u1ea1n th\u00ec kh\u00f4ng.<\/p>\n<blockquote><p><strong>Pro-\u0110\u1ea7u #5:<\/strong> \u0110\u1ed1i v\u1edbi b\u1ebfp th\u01b0\u01a1ng m\u1ea1i, h\u00e3y gi\u1ea3 \u0111\u1ecbnh <strong>t\u1ea5t c\u1ea3 c\u00e1c thi\u1ebft b\u1ecb n\u1ea5u n\u01b0\u1edbng \u0111\u1ec1u ho\u1ea1t \u0111\u1ed9ng li\u00ean t\u1ee5c<\/strong>. Ngay c\u1ea3 khi nh\u00e0 h\u00e0ng kh\u00f4ng m\u1edf c\u1eeda 24\/7, t\u00ednh to\u00e1n t\u1ea3i NEC cho n\u1ea5u \u0103n th\u01b0\u01a1ng m\u1ea1i v\u1eabn coi n\u00f3 l\u00e0 t\u1ea3i li\u00ean t\u1ee5c theo B\u1ea3ng 220.56. \u0110i\u1ec1u n\u00e0y khi\u1ebfn nhi\u1ec1u nh\u00e0 thi\u1ebft k\u1ebf b\u1ea5t ng\u1edd khi t\u00ednh to\u00e1n b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n b\u1ebfp 200A c\u1ee7a h\u1ecd tr\u1edf l\u1ea1i \u1edf m\u1ee9c t\u1ed1i thi\u1ec3u 260A sau h\u1ec7 s\u1ed1 nh\u00e2n 125%.<\/p><\/blockquote>\n<h3>B\u01b0\u1edbc 2: X\u00e1c \u0111\u1ecbnh d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n<\/h3>\n<p>NEC 110.9: \u201cThi\u1ebft b\u1ecb d\u1ef1 \u0111\u1ecbnh ng\u1eaft d\u00f2ng \u0111i\u1ec7n \u1edf m\u1ee9c s\u1ef1 c\u1ed1 ph\u1ea3i c\u00f3 \u0111\u1ecbnh m\u1ee9c ng\u1eaft \u00edt nh\u1ea5t b\u1eb1ng d\u00f2ng ng\u1eafn m\u1ea1ch t\u1ed1i \u0111a c\u00f3 s\u1eb5n t\u1ea1i \u0111i\u1ec3m \u1ee9ng d\u1ee5ng c\u1ee7a n\u00f3.\u201d<\/p>\n<p>NEC 110.24(A): \u201cD\u00f2ng s\u1ef1 c\u1ed1 t\u1ed1i \u0111a c\u00f3 s\u1eb5n\u2026ph\u1ea3i \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u t\u1ea1i ch\u1ed7 tr\u00ean\u2026thi\u1ebft b\u1ecb d\u1ecbch v\u1ee5\u2026t\u1ea1i c\u00e1c t\u00f2a nh\u00e0 ho\u1eb7c c\u00f4ng tr\u00ecnh \u0111\u01b0\u1ee3c c\u1ea5p ngu\u1ed3n b\u1eb1ng feeder ho\u1eb7c m\u1ea1ch nh\u00e1nh.\u201d (Ngo\u1ea1i l\u1ec7 \u0111\u1ed1i v\u1edbi nh\u00e0 \u1edf m\u1ed9t v\u00e0 hai gia \u0111\u00ecnh.)<\/p>\n<p>B\u1ea1n <strong>ph\u1ea3i<\/strong> t\u00ednh to\u00e1n \u0111i\u1ec1u n\u00e0y. N\u00f3 kh\u00f4ng ph\u1ea3i l\u00e0 t\u00f9y ch\u1ecdn cho c\u00f4ng vi\u1ec7c th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p.<\/p>\n<p><strong>L\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 c\u00f3 \u0111\u01b0\u1ee3c con s\u1ed1:<\/strong><\/p>\n<ol>\n<li><strong>H\u1ecfi c\u00f4ng ty \u0111i\u1ec7n l\u1ef1c:<\/strong> H\u1ea7u h\u1ebft c\u00e1c c\u00f4ng ty \u0111i\u1ec7n l\u1ef1c s\u1ebd cung c\u1ea5p d\u1eef li\u1ec7u d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n cho \u0111i\u1ec3m d\u1ecbch v\u1ee5. D\u1ef1 ki\u1ebfn 5-10 ng\u00e0y l\u00e0m vi\u1ec7c cho y\u00eau c\u1ea7u.<\/li>\n<li><strong>T\u00ednh to\u00e1n t\u1eeb d\u1eef li\u1ec7u m\u00e1y bi\u1ebfn \u00e1p:<\/strong> N\u1ebfu b\u1ea1n c\u00f3 quy\u1ec1n truy c\u1eadp v\u00e0o b\u1ea3ng t\u00ean m\u00e1y bi\u1ebfn \u00e1p (\u0111\u1ecbnh m\u1ee9c kVA, tr\u1edf kh\u00e1ng %), b\u1ea1n c\u00f3 th\u1ec3 t\u00ednh d\u00f2ng s\u1ef1 c\u1ed1 b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng:<strong>D\u00f2ng s\u1ef1 c\u1ed1 (A) = (kVA m\u00e1y bi\u1ebfn \u00e1p \u00d7 1000) \/ (\u221a3 \u00d7 \u0110i\u1ec7n \u00e1p \u00d7 %Z\/100)<\/strong>V\u00ed d\u1ee5: M\u00e1y bi\u1ebfn \u00e1p 500 kVA, 480V, tr\u1edf kh\u00e1ng 3,5%:\n<p>D\u00f2ng s\u1ef1 c\u1ed1 = (500.000) \/ (1,732 \u00d7 480 \u00d7 0,035) = <strong>17.182A \u1edf th\u1ee9 c\u1ea5p m\u00e1y bi\u1ebfn \u00e1p<\/strong><\/p>\n<p>\u0110i\u1ec1u n\u00e0y gi\u1ea3m theo kho\u1ea3ng c\u00e1ch do tr\u1edf kh\u00e1ng d\u00e2y d\u1eabn, nh\u01b0ng t\u1ea1i b\u1ea3ng ph\u00e2n ph\u1ed1i \u0111\u1ea7u ti\u00ean, h\u00e3y gi\u1ea3 s\u1eed 80-90% gi\u00e1 tr\u1ecb n\u00e0y.<\/li>\n<li><strong>S\u1eed d\u1ee5ng m\u00e1y t\u00ednh d\u00f2ng s\u1ef1 c\u1ed1:<\/strong> IEEE v\u00e0 m\u1ed9t s\u1ed1 nh\u00e0 s\u1ea3n xu\u1ea5t cung c\u1ea5p c\u00e1c c\u00f4ng c\u1ee5 t\u00ednh to\u00e1n.<\/li>\n<\/ol>\n<p>Khi b\u1ea1n c\u00f3 con s\u1ed1 n\u00e0y, h\u00e3y so s\u00e1nh n\u00f3 v\u1edbi \u0111\u1ecbnh m\u1ee9c ng\u1eafn m\u1ea1ch c\u1ee7a panelboard c\u1ee7a b\u1ea1n. N\u1ebfu \u0111\u1ecbnh m\u1ee9c c\u1ee7a panelboard nh\u1ecf h\u01a1n d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n, b\u1ea1n c\u00f3 ba l\u1ef1a ch\u1ecdn:<\/p>\n<ul>\n<li><strong>Ch\u1ecdn M\u1ed9t:<\/strong> Ch\u1ec9 \u0111\u1ecbnh m\u1ed9t panelboard c\u00f3 \u0111\u1ecbnh m\u1ee9c cao h\u01a1n (42kA, 65kA, v.v.)<\/li>\n<li><strong>L\u1ef1a ch\u1ecdn B:<\/strong> S\u1eed d\u1ee5ng b\u1ea3o v\u1ec7 \u0111\u1ecbnh m\u1ee9c n\u1ed1i ti\u1ebfp theo NEC 240.86 (y\u00eau c\u1ea7u c\u00e1c k\u1ebft h\u1ee3p \u0111\u01b0\u1ee3c ki\u1ec3m tra c\u1ee5 th\u1ec3)<\/li>\n<li><strong>L\u1ef1a ch\u1ecdn C:<\/strong> Th\u00eam c\u00e1c thi\u1ebft b\u1ecb gi\u1edbi h\u1ea1n d\u00f2ng \u0111i\u1ec7n \u1edf ph\u00eda tr\u00ean<\/li>\n<\/ul>\n<p>\u0110\u1ed1i v\u1edbi h\u1ea7u h\u1ebft c\u00e1c c\u00e0i \u0111\u1eb7t, T\u00f9y ch\u1ecdn A l\u00e0 \u0111\u01a1n gi\u1ea3n nh\u1ea5t v\u00e0 \u0111\u00e1ng tin c\u1eady nh\u1ea5t.<\/p>\n<p><strong>H\u00e3y nh\u1edb \u201cC\u00e1i b\u1eaby m\u1eb7c \u0111\u1ecbnh 10kA\u201d:<\/strong> N\u1ebfu panelboard c\u1ee7a b\u1ea1n ch\u1ec9 \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea l\u00e0 \u201cPanelboard\u201d (kh\u00f4ng ph\u1ea3i \u201cPanelboard k\u00edn\u201d), v\u00e0 d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n c\u1ee7a b\u1ea1n tr\u00ean 10kA, b\u1ea1n \u0111ang vi ph\u1ea1m NEC 110.9. Vi\u1ec7c c\u00e0i \u0111\u1eb7t s\u1ebd kh\u00f4ng v\u01b0\u1ee3t qua ki\u1ec3m tra.<\/p>\n<h3>B\u01b0\u1edbc 3: L\u1eadp k\u1ebf ho\u1ea1ch cho s\u1ef1 ph\u00e1t tri\u1ec3n (M\u00e1y t\u00ednh thu\u1ebf m\u1edf r\u1ed9ng)<\/h3>\n<p>\u0110\u00e2y l\u00e0 n\u01a1i c\u00e1c trung t\u00e2m t\u1ea3i ch\u1ebft\u2014kh\u00f4ng ph\u1ea3i do s\u1ef1 thi\u1ebfu h\u1ee5t k\u1ef9 thu\u1eadt ng\u00e0y nay, m\u00e0 l\u00e0 do <strong>kh\u00f4ng c\u00f3 s\u1ef1 linh ho\u1ea1t v\u00e0o ng\u00e0y mai<\/strong>.<\/p>\n<p><strong>Thu\u1ebf m\u1edf r\u1ed9ng<\/strong> l\u00e0 t\u1ed5ng chi ph\u00ed thay th\u1ebf thi\u1ebft b\u1ecb kh\u00f4ng \u0111\u1ee7 k\u00edch th\u01b0\u1edbc, \u0111\u01b0\u1ee3c t\u00ednh nh\u01b0 sau:<\/p>\n<p><strong>Thu\u1ebf m\u1edf r\u1ed9ng = (Chi ph\u00ed thay th\u1ebf + Nh\u00e2n c\u00f4ng l\u1eafp \u0111\u1eb7t + Chi ph\u00ed th\u1eddi gian ng\u1eebng ho\u1ea1t \u0111\u1ed9ng + Ph\u00ed gi\u1ea5y ph\u00e9p) \u00f7 S\u1ed1 n\u0103m cho \u0111\u1ebfn khi thay th\u1ebf<\/strong><\/p>\n<p><strong>Th\u1ebf gi\u1edbi th\u1ef1c, v\u00ed d\u1ee5:<\/strong><\/p>\n<p><strong>K\u1ecbch b\u1ea3n:<\/strong> T\u00f2a nh\u00e0 v\u0103n ph\u00f2ng th\u01b0\u01a1ng m\u1ea1i r\u1ed9ng 3.000 sq ft, t\u00ednh to\u00e1n t\u1ea3i ban \u0111\u1ea7u: 180A<\/p>\n<p><strong>T\u00f9y ch\u1ecdn A: Trung t\u00e2m t\u1ea3i 200A<\/strong><\/p>\n<ul>\n<li>Chi ph\u00ed thi\u1ebft b\u1ecb: $450<\/li>\n<li>L\u1eafp \u0111\u1eb7t: $600<\/li>\n<li>T\u1ed5ng ban \u0111\u1ea7u: $1.050<\/li>\n<\/ul>\n<p><strong>D\u00f2ng th\u1eddi gian:<\/strong><\/p>\n<ul>\n<li>N\u0103m 0: 26 m\u1ea1ch \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t, 4 kh\u00f4ng gian c\u00f2n l\u1ea1i (b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n 30 kh\u00f4ng gian)<\/li>\n<li>N\u0103m 2: C\u1ea3i thi\u1ec7n cho ng\u01b0\u1eddi thu\u00ea y\u00eau c\u1ea7u 8 m\u1ea1ch m\u1edbi\u2014b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n \u0111\u1ea7y + thi\u1ebfu 4 m\u1ea1ch<\/li>\n<li>Chi ph\u00ed n\u0103m 2: Thay th\u1ebf b\u1eb1ng panelboard 400A ($2.200) + nh\u00e2n c\u00f4ng ($1.500) + th\u1eddi gian ng\u1eebng ho\u1ea1t \u0111\u1ed9ng trong gi\u1edd l\u00e0m vi\u1ec7c (m\u1ea5t n\u0103ng su\u1ea5t ~ $2.000) + gi\u1ea5y ph\u00e9p ($180) = <strong>$5,880<\/strong><\/li>\n<\/ul>\n<p><strong>T\u1ed5ng chi ph\u00ed 5 n\u0103m:<\/strong> $1,050 + $5,880 = <strong>$6,930<\/strong><\/p>\n<p><strong>Thu\u1ebf m\u1edf r\u1ed9ng:<\/strong> $5.880 \u00f7 2 n\u0103m = <strong>Ph\u1ea1t $2.940\/n\u0103m<\/strong><\/p>\n<hr \/>\n<p><strong>T\u00f9y ch\u1ecdn B: Panelboard 400A v\u1edbi 42 kh\u00f4ng gian<\/strong><\/p>\n<ul>\n<li>Chi ph\u00ed thi\u1ebft b\u1ecb: $1.850<\/li>\n<li>L\u1eafp \u0111\u1eb7t: $950<\/li>\n<li>T\u1ed5ng ban \u0111\u1ea7u: $2.800<\/li>\n<\/ul>\n<p><strong>D\u00f2ng th\u1eddi gian:<\/strong><\/p>\n<ul>\n<li>N\u0103m 0: 26 m\u1ea1ch \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t, <strong>16 kh\u00f4ng gian c\u00f3 s\u1eb5n<\/strong><\/li>\n<li>N\u0103m 2: Th\u00eam 8 m\u1ea1ch (b\u00e2y gi\u1edd l\u00e0 34 m\u1ea1ch, 8 kh\u00f4ng gian v\u1eabn c\u00f2n)<\/li>\n<li>N\u0103m 5: Th\u00eam 6 m\u1ea1ch n\u1eefa (hi\u1ec7n t\u1ea1i 40 m\u1ea1ch, c\u00f2n 2 ch\u1ed7 tr\u1ed1ng)<\/li>\n<li>Chi ph\u00ed n\u0103m 5: $0<\/li>\n<\/ul>\n<p><strong>T\u1ed5ng chi ph\u00ed 5 n\u0103m:<\/strong> <strong>$2,800<\/strong><\/p>\n<p><strong>Thu\u1ebf m\u1edf r\u1ed9ng:<\/strong> <strong>$0\/n\u0103m<\/strong><\/p>\n<hr \/>\n<p><strong>Quy\u1ebft \u0111\u1ecbnh:<\/strong> Tr\u1ea3 tr\u01b0\u1edbc th\u00eam $1,750 \u0111\u1ec3 ti\u1ebft ki\u1ec7m $4,130 trong 5 n\u0103m. \u0110\u00f3 l\u00e0 m\u1ed9t <strong>ROI g\u1ea5p 2.4 l\u1ea7n<\/strong> tr\u00ean v\u1ed1n \u0111\u1ea7u t\u01b0 ban \u0111\u1ea7u, ch\u01b0a t\u00ednh \u0111\u1ebfn nh\u1eefng r\u1eafc r\u1ed1i c\u00f3 th\u1ec3 tr\u00e1nh \u0111\u01b0\u1ee3c khi \u0111i\u1ec1u ph\u1ed1i vi\u1ec7c thay th\u1ebf trong qu\u00e1 tr\u00ecnh v\u1eadn h\u00e0nh.<\/p>\n<blockquote><p><strong>M\u1eb9o chuy\u00ean nghi\u1ec7p #6: Ki\u1ec3m tra m\u1eadt \u0111\u1ed9 m\u1ea1ch<\/strong><\/p>\n<p>T\u00ednh to\u00e1n: <strong>Di\u1ec7n t\u00edch vu\u00f4ng \u00f7 S\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch<\/strong><\/p>\n<ul>\n<li>N\u1ebfu k\u1ebft qu\u1ea3 l\u00e0 <strong>&lt; 100 sq ft\/m\u1ea1ch<\/strong> \u2192 Kh\u1ea3 n\u0103ng cao s\u1ebd c\u1ea7n b\u1ed5 sung trong t\u01b0\u01a1ng lai. D\u1ef1 tr\u00f9 150% s\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch ban \u0111\u1ea7u.<\/li>\n<li>N\u1ebfu k\u1ebft qu\u1ea3 l\u00e0 <strong>100-150 sq ft\/m\u1ea1ch<\/strong> \u2192 D\u1ef1 ki\u1ebfn t\u0103ng tr\u01b0\u1edfng v\u1eeba ph\u1ea3i. D\u1ef1 tr\u00f9 125% s\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch ban \u0111\u1ea7u.<\/li>\n<li>N\u1ebfu k\u1ebft qu\u1ea3 l\u00e0 <strong>&gt; 150 sq ft\/m\u1ea1ch<\/strong> \u2192 M\u1eadt \u0111\u1ed9 th\u1ea5p, \u1ee9ng d\u1ee5ng \u1ed5n \u0111\u1ecbnh. D\u1ef1 tr\u00f9 110% s\u1ed1 l\u01b0\u1ee3ng m\u1ea1ch ban \u0111\u1ea7u (v\u1eabn c\u1ea7n m\u1ed9t s\u1ed1 kho\u1ea3ng tr\u1ed1ng).<\/li>\n<\/ul>\n<p>\u0110\u1ed1i v\u1edbi v\u0103n ph\u00f2ng 3.000 sq ft v\u1edbi 26 m\u1ea1ch: 3.000 \u00f7 26 = 115 sq ft\/m\u1ea1ch \u2192 Thu\u1ed9c danh m\u1ee5c t\u0103ng tr\u01b0\u1edfng v\u1eeba ph\u1ea3i \u2192 D\u1ef1 tr\u00f9 <strong>T\u1ed1i thi\u1ec3u 33 ch\u1ed7 tr\u1ed1ng<\/strong> (26 \u00d7 1.25), c\u00f3 ngh\u0129a l\u00e0 m\u1ed9t b\u1ea3ng \u0111i\u1ec7n 42 ch\u1ed7 l\u00e0 ph\u00f9 h\u1ee3p.<\/p><\/blockquote>\n<h3>B\u01b0\u1edbc 4: Ki\u1ec3m tra y\u00eau c\u1ea7u v\u1ec1 \u0111i\u1ec7n \u00e1p &amp; pha<\/h3>\n<p>\u0110\u00e2y l\u00e0 b\u01b0\u1edbc \u0111\u01a1n gi\u1ea3n nh\u1ea5t, nh\u01b0ng n\u00f3 l\u00e0 nh\u1ecb ph\u00e2n\u2014n\u1ebfu sai th\u00ec m\u1ecdi th\u1ee9 kh\u00e1c \u0111\u1ec1u kh\u00f4ng quan tr\u1ecdng.<\/p>\n<p><strong>\u1ee8ng d\u1ee5ng m\u1ed9t pha:<\/strong><\/p>\n<ul>\n<li>Khu d\u00e2n c\u01b0: 120\/240V (pha t\u00e1ch)<\/li>\n<li>Th\u01b0\u01a1ng m\u1ea1i nh\u1eb9 \u0111\u01b0\u1ee3c c\u1ea5p ngu\u1ed3n t\u1eeb \u0111i\u1ec7n l\u01b0\u1edbi m\u1ed9t pha: 120\/240V<\/li>\n<li>T\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i tr\u00ean \u0111i\u1ec7n l\u01b0\u1edbi ba pha v\u1edbi b\u1ea3ng \u0111i\u1ec7n m\u1ed9t pha: 120\/208V (c\u00f3 ngu\u1ed3n g\u1ed1c t\u1eeb h\u1ec7 th\u1ed1ng Wye)<\/li>\n<\/ul>\n<p>\u2192 Trung t\u00e2m t\u1ea3i ho\u1ea1t \u0111\u1ed9ng \u1edf \u0111\u00e2y, <em>n\u1ebfu<\/em> t\u1ea5t c\u1ea3 c\u00e1c ti\u00eau ch\u00ed kh\u00e1c \u0111\u1ec1u \u0111\u01b0\u1ee3c \u0111\u00e1p \u1ee9ng (c\u00f4ng su\u1ea5t, d\u00f2ng s\u1ef1 c\u1ed1, v.v.)<\/p>\n<p><strong>\u1ee8ng d\u1ee5ng ba pha:<\/strong><\/p>\n<ul>\n<li>208Y\/120V (th\u01b0\u01a1ng m\u1ea1i ph\u1ed5 bi\u1ebfn)<\/li>\n<li>480Y\/277V (c\u00f4ng nghi\u1ec7p, th\u01b0\u01a1ng m\u1ea1i l\u1edbn)<\/li>\n<li>600Y\/347V (Canada, m\u1ed9t s\u1ed1 ng\u00e0nh c\u00f4ng nghi\u1ec7p)<\/li>\n<li>240V Delta high-leg (th\u01b0\u01a1ng m\u1ea1i c\u0169, \u0111ang d\u1ea7n b\u1ecb lo\u1ea1i b\u1ecf)<\/li>\n<\/ul>\n<p>\u2192 <strong>Y\u00eau c\u1ea7u b\u1ea3ng \u0111i\u1ec7n.<\/strong> Kh\u00f4ng c\u00f3 ngo\u1ea1i l\u1ec7.<\/p>\n<p><strong>C\u00e1ch x\u00e1c \u0111\u1ecbnh:<\/strong> Nh\u00ecn v\u00e0o l\u1ed1i v\u00e0o d\u1ecbch v\u1ee5 ti\u1ec7n \u00edch. \u0110\u1ebfm d\u00e2y d\u1eabn:<\/p>\n<ul>\n<li>3 d\u00e2y d\u1eabn (2 n\u00f3ng + trung t\u00ednh) = M\u1ed9t pha<\/li>\n<li>4 d\u00e2y d\u1eabn (3 n\u00f3ng + trung t\u00ednh) = Ba pha Wye<\/li>\n<li>3 d\u00e2y d\u1eabn (3 n\u00f3ng, kh\u00f4ng trung t\u00ednh) = Ba pha Delta<\/li>\n<\/ul>\n<p>N\u1ebfu b\u1ea1n th\u1ea5y b\u1ed1n ho\u1eb7c ba d\u00e2y d\u1eabn t\u1ea1i d\u1ecbch v\u1ee5 v\u00e0 b\u1ea1n \u0111ang ph\u00e2n ph\u1ed1i cho t\u1ea3i th\u01b0\u01a1ng m\u1ea1i, b\u1ea1n \u0111ang \u1edf trong khu v\u1ef1c b\u1ea3ng \u0111i\u1ec7n.<\/p>\n<p><strong>C\u1ea3nh b\u00e1o v\u1ec1 h\u1ec7 th\u1ed1ng Delta high-leg:<\/strong> NEC 408.3(F) y\u00eau c\u1ea7u \u0111\u00e1nh d\u1ea5u \u0111\u1eb7c bi\u1ec7t: \u201cC\u1ea3nh b\u00e1o Pha ___ C\u00f3 ___ Volts so v\u1edbi \u0111\u1ea5t.\u201d (V\u00ed d\u1ee5: \u201cC\u1ea3nh b\u00e1o Pha B C\u00f3 208V so v\u1edbi \u0111\u1ea5t\u201d cho h\u1ec7 th\u1ed1ng Delta 240V.) C\u00e1c h\u1ec7 th\u1ed1ng n\u00e0y \u0111ang d\u1ea7n \u00edt \u0111\u01b0\u1ee3c \u01b0a chu\u1ed9ng nh\u01b0ng v\u1eabn t\u1ed3n t\u1ea1i trong c\u00e1c t\u00f2a nh\u00e0 c\u0169. N\u1ebfu b\u1ea1n \u0111ang l\u00e0m vi\u1ec7c v\u1edbi Delta high-leg, h\u00e3y x\u00e1c minh b\u1ea3ng \u0111i\u1ec7n c\u1ee7a b\u1ea1n \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 cho n\u00f3 v\u00e0 \u0111\u1ea3m b\u1ea3o d\u00e2y d\u1eabn high-leg k\u1ebft th\u00fac tr\u00ean pha ch\u00ednh x\u00e1c theo NEC 408.3(E).<\/p>\n<h3>B\u01b0\u1edbc 5: X\u00e1c minh <a href=\"https:\/\/test.viox.com\/vi\/mcb\/\">Breaker (\u00c1pt\u00f4m\u00e1t)<\/a> Y\u00eau c\u1ea7u v\u1ec1 lo\u1ea1i<\/h3>\n<p>Ngo\u00e0i vi\u1ec7c ch\u1ec9 l\u00e0 lo\u1ea1i c\u1eafm v\u00e0o so v\u1edbi lo\u1ea1i b\u1eaft v\u00edt, c\u00f2n c\u00f3 c\u00e1c y\u00eau c\u1ea7u c\u1ee5 th\u1ec3 c\u1ee7a NEC:<\/p>\n<p><strong>NEC 408.36(D) \u2013 Thi\u1ebft b\u1ecb c\u1ea5p ng\u01b0\u1ee3c:<\/strong><\/p>\n<p>\u201cC\u00e1c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng lo\u1ea1i c\u1eafm\u2026 \u0111\u01b0\u1ee3c c\u1ea5p ng\u01b0\u1ee3c v\u00e0 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 k\u1ebft th\u00fac d\u00e2y d\u1eabn cung c\u1ea5p kh\u00f4ng n\u1ed1i \u0111\u1ea5t \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t t\u1ea1i hi\u1ec7n tr\u01b0\u1eddng ph\u1ea3i \u0111\u01b0\u1ee3c c\u1ed1 \u0111\u1ecbnh t\u1ea1i ch\u1ed7 b\u1eb1ng m\u1ed9t b\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t b\u1ed5 sung y\u00eau c\u1ea7u m\u1ed9t thao t\u00e1c kh\u00e1c ngo\u00e0i vi\u1ec7c k\u00e9o \u0111\u1ec3 nh\u1ea3 thi\u1ebft b\u1ecb.\u201d<\/p>\n<p><strong>Bi\u00ean d\u1ecbch:<\/strong> N\u1ebfu b\u1ea1n \u0111ang s\u1eed d\u1ee5ng b\u1ed9 ng\u1eaft m\u1ea1ch lo\u1ea1i c\u1eafm \u0111\u1ec3 c\u1ea5p ngu\u1ed3n <strong>v\u00e0o<\/strong> cho thanh c\u00e1i c\u1ee7a b\u1ea3ng \u0111i\u1ec7n (k\u1ebft n\u1ed1i n\u0103ng l\u01b0\u1ee3ng m\u1eb7t tr\u1eddi, c\u1ea5p ng\u01b0\u1ee3c m\u00e1y ph\u00e1t \u0111i\u1ec7n, ngu\u1ed3n \u0111i\u1ec7n thay th\u1ebf), c\u00e1c k\u1eb9p ma s\u00e1t ti\u00eau chu\u1ea9n l\u00e0 kh\u00f4ng \u0111\u1ee7. B\u1ea1n c\u1ea7n m\u1ed9t v\u00edt gi\u1eef, gi\u00e1 \u0111\u1ee1 ho\u1eb7c b\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t c\u01a1 h\u1ecdc kh\u00e1c.<\/p>\n<p><strong>T\u1ea1i sao:<\/strong> M\u1ed9t b\u1ed9 ng\u1eaft m\u1ea1ch \u0111\u01b0\u1ee3c c\u1ea5p ng\u01b0\u1ee3c c\u00f3 \u0111i\u1ec7n \u00e1p \u0111\u01b0\u1eddng d\u00e2y tr\u00ean c\u00e1c \u0111\u1ea7u n\u1ed1i t\u1ea3i c\u1ee7a b\u1ed9 ng\u1eaft m\u1ea1ch, c\u00e1c \u0111\u1ea7u n\u1ed1i n\u00e0y s\u1ebd b\u1ecb l\u1ed9 khi b\u1ea1n th\u00e1o b\u1ed9 ng\u1eaft m\u1ea1ch kh\u1ecfi thanh c\u00e1i. N\u1ebfu kh\u00f4ng c\u00f3 b\u1ed9 ph\u1eadn si\u1ebft ch\u1eb7t b\u1ed5 sung, ai \u0111\u00f3 c\u00f3 th\u1ec3 v\u00f4 t\u00ecnh k\u00e9o b\u1ed9 ng\u1eaft m\u1ea1ch ra khi n\u00f3 \u0111ang ho\u1ea1t \u0111\u1ed9ng\u2014nguy c\u01a1 h\u1ed3 quang \u0111i\u1ec7n ngay l\u1eadp t\u1ee9c.<\/p>\n<p>Thanh tra vi\u00ean ki\u1ec3m tra \u0111i\u1ec1u n\u00e0y. H\u00e3y l\u1eafp \u0111\u1eb7t b\u1ed9 gi\u1eef <strong>tr\u01b0\u1edbc khi<\/strong> tr\u01b0\u1edbc khi ki\u1ec3m tra.<\/p>\n<p><strong>B\u1ed9 ng\u1eaft m\u1ea1ch \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u \u201c\u0110\u01b0\u1eddng d\u00e2y\u201d v\u00e0 \u201cT\u1ea3i\u201d:<\/strong><\/p>\n<p>NEC 110.3(B) y\u00eau c\u1ea7u l\u1eafp \u0111\u1eb7t theo danh s\u00e1ch v\u00e0 nh\u00e3n c\u1ee7a nh\u00e0 s\u1ea3n xu\u1ea5t. N\u1ebfu m\u1ed9t b\u1ed9 ng\u1eaft m\u1ea1ch \u0111\u01b0\u1ee3c \u0111\u00e1nh d\u1ea5u \u201c\u0110\u01b0\u1eddng d\u00e2y\u201d v\u00e0 \u201cT\u1ea3i\u201d, b\u1ea1n kh\u00f4ng \u0111\u01b0\u1ee3c <strong>kh\u00f4ng th\u1ec3<\/strong> c\u1ea5p ng\u01b0\u1ee3c n\u00f3. Ch\u1ea5m h\u1ebft. N\u00f3 kh\u00f4ng \u0111\u01b0\u1ee3c li\u1ec7t k\u00ea cho d\u00f2ng \u0111i\u1ec7n ng\u01b0\u1ee3c.<\/p>\n<p>Gi\u1ea3i ph\u00e1p: S\u1eed d\u1ee5ng b\u1ed9 ng\u1eaft m\u1ea1ch \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 \u0111\u1eb7c bi\u1ec7t cho c\u00e1c \u1ee9ng d\u1ee5ng c\u1ea5p ng\u01b0\u1ee3c ho\u1eb7c s\u1eed d\u1ee5ng b\u1ed9 ng\u1eaft m\u1ea1ch b\u1eaft v\u00edt th\u01b0\u1eddng l\u00e0 hai chi\u1ec1u.<\/p>\n<h3>B\u01b0\u1edbc 6: M\u00f4i tr\u01b0\u1eddng &amp; Y\u00eau c\u1ea7u c\u1ee5 th\u1ec3 theo quy \u0111\u1ecbnh<\/h3>\n<p>Ki\u1ec3m tra cu\u1ed1i c\u00f9ng tr\u01b0\u1edbc khi mua s\u1eafm:<\/p>\n<p><strong>NEC 408.43 \u2013 V\u1ecb tr\u00ed:<\/strong><\/p>\n<p>\u201cB\u1ea3ng \u0111i\u1ec7n kh\u00f4ng \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t \u1edf v\u1ecb tr\u00ed \u00fap m\u1eb7t l\u00ean ho\u1eb7c \u00fap m\u1eb7t xu\u1ed1ng.\u201d<\/p>\n<p>C\u00e1c b\u1ea3ng \u0111i\u1ec7n ph\u1ea3i th\u1eb3ng \u0111\u1ee9ng ho\u1eb7c n\u1eb1m ngang v\u1edbi n\u1eafp h\u01b0\u1edbng v\u1ec1 b\u1ec1 m\u1eb7t th\u1eb3ng \u0111\u1ee9ng (t\u01b0\u1eddng). \u0110i\u1ec1u n\u00e0y ng\u0103n ng\u1eeba s\u1ef1 t\u00edch t\u1ee5 m\u1ea3nh v\u1ee5n v\u00e0 s\u1ef1 x\u00e2m nh\u1eadp c\u1ee7a ch\u1ea5t l\u1ecfng v\u00e0o khoang thanh c\u00e1i. Ch\u00fang t\u00f4i \u0111\u00e3 th\u1ea5y c\u00e1c c\u00e0i \u0111\u1eb7t trong \u0111\u00f3 c\u00e1c b\u1ea3ng \u0111i\u1ec7n \u0111\u01b0\u1ee3c g\u1eafn theo chi\u1ec1u ngang tr\u00ean tr\u1ea7n nh\u00e0 v\u1edbi n\u1eafp h\u01b0\u1edbng xu\u1ed1ng\u2014s\u1eed d\u1ee5ng kh\u00f4ng gian s\u00e1ng t\u1ea1o, nh\u01b0ng b\u1ecb g\u1eafn c\u1edd ngay l\u1eadp t\u1ee9c.<\/p>\n<p><strong>NEC 408.4 \u2013 Danh m\u1ee5c m\u1ea1ch:<\/strong><\/p>\n<p>\u201cM\u1ecdi m\u1ea1ch v\u00e0 s\u1eeda \u0111\u1ed5i m\u1ea1ch ph\u1ea3i \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh m\u1ed9t c\u00e1ch d\u1ec5 \u0111\u1ecdc v\u1ec1 m\u1ee5c \u0111\u00edch ho\u1eb7c m\u1ee5c \u0111\u00edch s\u1eed d\u1ee5ng r\u00f5 r\u00e0ng, hi\u1ec3n nhi\u00ean v\u00e0 c\u1ee5 th\u1ec3 c\u1ee7a n\u00f3.\u201d<\/p>\n<p>\u201c\u1ede nh\u1eefng n\u01a1i kh\u00e1c ngo\u00e0i nh\u00e0 \u1edf m\u1ed9t v\u00e0 hai gia \u0111\u00ecnh, vi\u1ec7c x\u00e1c \u0111\u1ecbnh ph\u1ea3i bao g\u1ed3m \u0111\u1ee7 chi ti\u1ebft \u0111\u1ec3 cho ph\u00e9p ph\u00e2n bi\u1ec7t t\u1eebng m\u1ea1ch v\u1edbi t\u1ea5t c\u1ea3 c\u00e1c m\u1ea1ch kh\u00e1c.\u201d<\/p>\n<p>Vi\u1ec7c d\u00e1n nh\u00e3n m\u01a1 h\u1ed3 nh\u01b0 \u201c\u0110\u00e8n,\u201d \u201c\u1ed4 c\u1eafm,\u201d \u201cLinh tinh\u201d s\u1ebd kh\u00f4ng \u0111\u1ea1t ki\u1ec3m tra th\u01b0\u01a1ng m\u1ea1i. B\u1ea1n c\u1ea7n c\u1ee5 th\u1ec3: \u201cKhu v\u1ef1c Chi\u1ebfu s\u00e1ng V\u0103n ph\u00f2ng Ph\u00eda B\u1eafc Khu 1-3,\u201d \u201c\u1ed4 c\u1eafm Chuy\u00ean d\u1ee5ng Ph\u00f2ng M\u00e1y ch\u1ee7,\u201d \u201cT\u1ed5 m\u00e1y HVAC 2 \u2013 M\u00e1i nh\u00e0.\u201d<\/p>\n<p>Th\u1ef1c h\u00e0nh t\u1ed1t nh\u1ea5t: S\u1eed d\u1ee5ng m\u00e1y in nh\u00e3n chuy\u00ean nghi\u1ec7p ho\u1eb7c c\u00e1c mi\u1ebfng ch\u00e8n th\u01b0 m\u1ee5c in s\u1eb5n. Th\u01b0 m\u1ee5c vi\u1ebft tay v\u1ec1 m\u1eb7t k\u1ef9 thu\u1eadt c\u00f3 th\u1ec3 ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c nh\u01b0ng ph\u1ea3n \u00e1nh ch\u1ea5t l\u01b0\u1ee3ng l\u1eafp \u0111\u1eb7t k\u00e9m.<\/p>\n<p><strong>Y\u00eau c\u1ea7u v\u1ec1 \u0110\u1ecba \u0111i\u1ec3m Nguy hi\u1ec3m:<\/strong><\/p>\n<p>N\u1ebfu b\u1ea3ng \u0111i\u1ec7n c\u1ee7a b\u1ea1n \u1edf \u0111\u1ecba \u0111i\u1ec3m nguy hi\u1ec3m Lo\u1ea1i I, II ho\u1eb7c III (nh\u00e0 m\u00e1y h\u00f3a ch\u1ea5t, x\u1eed l\u00fd ng\u0169 c\u1ed1c, bu\u1ed3ng phun s\u01a1n, v.v.), th\u00ec c\u00e1c trung t\u00e2m t\u1ea3i ti\u00eau chu\u1ea9n v\u00e0 b\u1ea3ng \u0111i\u1ec7n \u0111a n\u0103ng kh\u00f4ng ph\u00f9 h\u1ee3p. B\u1ea1n c\u1ea7n:<\/p>\n<ul>\n<li>Lo\u1ea1i I Div 1: B\u1ea3ng \u0111i\u1ec7n ch\u1ed1ng ch\u00e1y n\u1ed5 ho\u1eb7c \u0111\u01b0\u1ee3c l\u00e0m s\u1ea1ch\/t\u1ea1o \u00e1p l\u1ef1c theo NEC 501.6<\/li>\n<li>Lo\u1ea1i I Div 2: \u0110a n\u0103ng trong m\u1ed9t s\u1ed1 tr\u01b0\u1eddng h\u1ee3p, ch\u1ed1ng ch\u00e1y n\u1ed5 trong c\u00e1c tr\u01b0\u1eddng h\u1ee3p kh\u00e1c theo NEC 501.115<\/li>\n<li>Lo\u1ea1i II (b\u1ee5i): V\u1ecf ch\u1ed1ng ch\u00e1y b\u1ee5i theo NEC 502.115<\/li>\n<\/ul>\n<p>\u0110\u00e2y l\u00e0 nh\u1eefng b\u1ea3ng \u0111i\u1ec7n chuy\u00ean d\u1ee5ng, kh\u00f4ng c\u00f3 s\u1eb5n trong c\u1ea5u h\u00ecnh trung t\u00e2m t\u1ea3i.<\/p>\n<p><strong>X\u1ebfp h\u1ea1ng NEMA v\u1ec1 M\u00f4i tr\u01b0\u1eddng:<\/strong><\/p>\n<p>Gh\u00e9p lo\u1ea1i NEMA v\u1edbi m\u00f4i tr\u01b0\u1eddng:<\/p>\n<ul>\n<li><strong>Lo\u1ea1i 1:<\/strong> \u0110\u1ecba \u0111i\u1ec3m trong nh\u00e0, kh\u00f4 r\u00e1o (\u0111a n\u0103ng)<\/li>\n<li><strong>Lo\u1ea1i 3R:<\/strong> Ngo\u00e0i tr\u1eddi, ch\u1ed1ng m\u01b0a<\/li>\n<li><strong>Lo\u1ea1i 4:<\/strong> Ch\u1ed1ng th\u1ea5m n\u01b0\u1edbc (kh\u00f4ng ng\u00e2m \u0111\u01b0\u1ee3c)<\/li>\n<li><strong>Lo\u1ea1i 4X:<\/strong> Ch\u1ed1ng th\u1ea5m n\u01b0\u1edbc, ch\u1ed1ng \u0103n m\u00f2n (th\u00e9p kh\u00f4ng g\u1ec9 ho\u1eb7c s\u1ee3i th\u1ee7y tinh)<\/li>\n<li><strong>Lo\u1ea1i 12:<\/strong> C\u00f4ng nghi\u1ec7p, ch\u1ed1ng b\u1ee5i\/nh\u1ecf gi\u1ecdt<\/li>\n<\/ul>\n<p>B\u1ea3ng th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt c\u1ee7a b\u1ea1n ph\u1ea3i n\u00eau r\u00f5 lo\u1ea1i NEMA c\u1ea7n thi\u1ebft. \u0110\u1eebng cho r\u1eb1ng \u201ctrong nh\u00e0\u201d c\u00f3 ngh\u0129a l\u00e0 Lo\u1ea1i 1 n\u1ebfu \u0111\u1ecba \u0111i\u1ec3m l\u00e0 b\u1ebfp th\u01b0\u01a1ng m\u1ea1i c\u00f3 h\u01a1i n\u01b0\u1edbc ho\u1eb7c nh\u00e0 kho c\u00f3 c\u1eeda tr\u00ean cao ti\u1ebfp x\u00fac v\u1edbi th\u1eddi ti\u1ebft.<\/p>\n<h2>Khi n\u00e0o n\u00ean Ch\u1ecdn Lo\u1ea1i N\u00e0o: Tham kh\u1ea3o Nhanh<\/h2>\n<p><strong>Ma Tr\u1eadn Quy\u1ebft \u0110\u1ecbnh:<\/strong><\/p>\n<table border=\"1\">\n<thead>\n<tr>\n<th>Y\u1ebfu T\u1ed1 L\u1ef1a Ch\u1ecdn<\/th>\n<th>Ch\u1ecdn Trung t\u00e2m T\u1ea3i Khi\u2026<\/th>\n<th>Ch\u1ecdn B\u1ea3ng \u0111i\u1ec7n Khi\u2026<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u0110i\u1ec7n \u00e1p\/Pha<\/td>\n<td>M\u1ed9t pha, 120\/240V ho\u1eb7c 120\/208V<\/td>\n<td>Ba pha, ho\u1eb7c &gt;240V<\/td>\n<\/tr>\n<tr>\n<td>C\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n<\/td>\n<td>\u2264200A t\u1ea3i t\u00ednh to\u00e1n<\/td>\n<td>&gt;200A t\u1ea3i t\u00ednh to\u00e1n<\/td>\n<\/tr>\n<tr>\n<td>D\u00f2ng \u0111i\u1ec7n S\u1ef1 c\u1ed1<\/td>\n<td>&lt;10kA kh\u1ea3 d\u1ee5ng (x\u00e1c minh danh s\u00e1ch k\u00e8m theo)<\/td>\n<td>&gt;10kA kh\u1ea3 d\u1ee5ng, ho\u1eb7c &gt;22kA \u0111\u1ec3 c\u00f3 bi\u00ean \u0111\u1ed9 an to\u00e0n<\/td>\n<\/tr>\n<tr>\n<td>\u1ee8ng d\u1ee5ng<\/td>\n<td>Khu d\u00e2n c\u01b0, th\u01b0\u01a1ng m\u1ea1i m\u1ed9t ng\u01b0\u1eddi thu\u00ea nh\u1ecf<\/td>\n<td>Th\u01b0\u01a1ng m\u1ea1i nhi\u1ec1u ng\u01b0\u1eddi thu\u00ea, c\u00f4ng nghi\u1ec7p, c\u01a1 s\u1edf quan tr\u1ecdng<\/td>\n<\/tr>\n<tr>\n<td>K\u1ef3 v\u1ecdng T\u0103ng tr\u01b0\u1edfng<\/td>\n<td>Chi\u1ebfm d\u1ee5ng c\u1ed1 \u0111\u1ecbnh, kh\u00f4ng d\u1ef1 ki\u1ebfn m\u1edf r\u1ed9ng<\/td>\n<td>Thay \u0111\u1ed5i ng\u01b0\u1eddi thu\u00ea, k\u1ebf ho\u1ea1ch m\u1edf r\u1ed9ng ho\u1eb7c &gt;100 sq ft\/m\u1ea1ch<\/td>\n<\/tr>\n<tr>\n<td>Lo\u1ea1i m\u00e1y c\u1eaft<\/td>\n<td>C\u00f3 th\u1ec3 c\u1eafm v\u00e0o, kh\u00f4ng c\u00f3 c\u1ea5p ng\u01b0\u1ee3c<\/td>\n<td>Y\u00eau c\u1ea7u b\u1eaft v\u00edt, \u1ee9ng d\u1ee5ng c\u1ea5p ng\u01b0\u1ee3c, \u0111\u1ed9 rung cao<\/td>\n<\/tr>\n<tr>\n<td>M\u00f4i tr\u01b0\u1eddng<\/td>\n<td>Trong nh\u00e0, kh\u00f4 r\u00e1o, ki\u1ec3m so\u00e1t kh\u00ed h\u1eadu<\/td>\n<td>Ngo\u00e0i tr\u1eddi, \u1ea9m \u01b0\u1edbt\/\u0103n m\u00f2n, \u0111\u1ecba \u0111i\u1ec3m nguy hi\u1ec3m<\/td>\n<\/tr>\n<tr>\n<td>Dung sai Ng\u00e2n s\u00e1ch<\/td>\n<td>Chi ph\u00ed ban \u0111\u1ea7u th\u1ea5p nh\u1ea5t tuy\u1ec7t \u0111\u1ed1i l\u00e0 r\u1ea5t quan tr\u1ecdng<\/td>\n<td>\u01afu ti\u00ean chi ph\u00ed v\u00f2ng \u0111\u1eddi v\u00e0 TCO<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h3>Nghi\u00ean c\u1ee9u \u0111i\u1ec3n h\u00ecnh 1: Khi Trung t\u00e2m T\u1ea3i l\u00e0 L\u1ef1a ch\u1ecdn \u0110\u00fang \u0111\u1eafn<\/h3>\n<p><strong>D\u1ef1 \u00e1n:<\/strong> Nh\u00e0 \u0111\u1ec3 xe\/x\u01b0\u1edfng l\u00e0m vi\u1ec7c d\u00e2n c\u01b0 r\u1ed9ng 1.800 sq ft<\/p>\n<p><strong>T\u1ea3i:<\/strong><\/p>\n<ul>\n<li>Chi\u1ebfu s\u00e1ng: 12A (li\u00ean t\u1ee5c)<\/li>\n<li>\u1ed4 c\u1eafm (\u0111a n\u0103ng): 30A (kh\u00f4ng li\u00ean t\u1ee5c)<\/li>\n<li>M\u00e1y n\u00e9n kh\u00ed 240V: 20A (kh\u00f4ng li\u00ean t\u1ee5c)<\/li>\n<li>M\u00e1y h\u00e0n 240V: 30A (gi\u00e1n \u0111o\u1ea1n, d\u00f2ng kh\u1edfi \u0111\u1ed9ng cao)<\/li>\n<\/ul>\n<p><strong>T\u00ednh to\u00e1n:<\/strong><\/p>\n<ul>\n<li>Li\u00ean t\u1ee5c: 12A \u00d7 125% = 15A<\/li>\n<li>Kh\u00f4ng li\u00ean t\u1ee5c: 30 + 20 + 30 = 80A<\/li>\n<li>T\u1ed5ng: 15 + 80 = 95A<\/li>\n<\/ul>\n<p><strong>L\u1ef1a ch\u1ecdn:<\/strong> Trung t\u00e2m t\u1ea3i 100A, 20 ch\u1ed7, b\u1ed9 ng\u1eaft m\u1ea1ch c\u1eafm v\u00e0o<\/p>\n<ul>\n<li>D\u00f2ng s\u1ef1 c\u1ed1 kh\u1ea3 d\u1ee5ng t\u1ea1i \u0111\u1ecba \u0111i\u1ec3m: 6,5kA (\u0111\u00e3 x\u00e1c minh v\u1edbi ti\u1ec7n \u00edch)<\/li>\n<li>Trung t\u00e2m t\u1ea3i \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 22kA (danh s\u00e1ch b\u1ea3ng \u0111i\u1ec7n k\u00e8m theo)<\/li>\n<li>Chi ph\u00ed: $285 thi\u1ebft b\u1ecb + $450 l\u1eafp \u0111\u1eb7t = <strong>$735 t\u1ed5ng<\/strong><\/li>\n<\/ul>\n<p><strong>K\u1ebft qu\u1ea3:<\/strong> \u1ee8ng d\u1ee5ng ho\u00e0n to\u00e0n ph\u00f9 h\u1ee3p. S\u1eed d\u1ee5ng d\u00e2n c\u01b0 c\u1ed1 \u0111\u1ecbnh, d\u00f2ng s\u1ef1 c\u1ed1 th\u1ea5p, m\u1ed9t pha 120\/240V \u0111\u01a1n gi\u1ea3n, kh\u00f4ng d\u1ef1 ki\u1ebfn m\u1edf r\u1ed9ng (x\u01b0\u1edfng l\u00e0 thi\u1ebft k\u1ebf tr\u1ea1ng th\u00e1i cu\u1ed1i). Trung t\u00e2m t\u1ea3i ti\u1ebft ki\u1ec7m $600-800 so v\u1edbi b\u1ea3ng \u0111i\u1ec7n th\u01b0\u01a1ng m\u1ea1i m\u00e0 kh\u00f4ng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn hi\u1ec7u su\u1ea5t.<\/p>\n<h3>Nghi\u00ean c\u1ee9u \u0111i\u1ec3n h\u00ecnh 2: Thu\u1ebf M\u1edf r\u1ed9ng trong H\u00e0nh \u0111\u1ed9ng<\/h3>\n<p><strong>D\u1ef1 \u00e1n:<\/strong> Kh\u00f4ng gian b\u00e1n l\u1ebb th\u01b0\u01a1ng m\u1ea1i r\u1ed9ng 2.400 sq ft trong trung t\u00e2m mua s\u1eafm<\/p>\n<p><strong>T\u1ea3i ban \u0111\u1ea7u (N\u0103m 0):<\/strong><\/p>\n<ul>\n<li>Chi\u1ebfu s\u00e1ng: 45A (li\u00ean t\u1ee5c \u2013 LED xuy\u00ean su\u1ed1t)<\/li>\n<li>\u1ed4 c\u1eafm: 40A (kh\u00f4ng li\u00ean t\u1ee5c)<\/li>\n<li>HVAC (RTU): 28A (li\u00ean t\u1ee5c)<\/li>\n<li>Bi\u1ec3n b\u00e1o: 8A (li\u00ean t\u1ee5c)<\/li>\n<\/ul>\n<p><strong>T\u00ednh to\u00e1n ban \u0111\u1ea7u:<\/strong><\/p>\n<ul>\n<li>Li\u00ean t\u1ee5c: (45 + 28 + 8) \u00d7 125% = 101.25A<\/li>\n<li>Kh\u00f4ng li\u00ean t\u1ee5c: 40A<\/li>\n<li>T\u1ed5ng: 141.25A \u2192 <strong>T\u1ed1i thi\u1ec3u 150A<\/strong><\/li>\n<\/ul>\n<p><strong>L\u1ef1a ch\u1ecdn th\u1ef1c t\u1ebf:<\/strong> Trung t\u00e2m t\u1ea3i 200A, 30 ch\u1ed7<\/p>\n<ul>\n<li>Thi\u1ebft b\u1ecb: $1,520<\/li>\n<li>L\u1eafp \u0111\u1eb7t: $680<\/li>\n<li>T\u1ed5ng: $1,200<\/li>\n<\/ul>\n<p><strong>\u0110\u00e1nh gi\u00e1 ban \u0111\u1ea7u:<\/strong> \u201cTuy\u1ec7t v\u1eddi! Ch\u00fang ta c\u00f3 t\u00ednh to\u00e1n 150A, b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n 200A v\u00e0 ch\u1ec9 s\u1eed d\u1ee5ng 22 trong s\u1ed1 30 ch\u1ed7. R\u1ea5t nhi\u1ec1u ch\u1ed7 tr\u1ed1ng.\u201d<\/p>\n<hr \/>\n<p><strong>N\u0103m 2: C\u1ea3i thi\u1ec7n m\u1eb7t b\u1eb1ng cho ng\u01b0\u1eddi thu\u00ea \u0111\u1ea7u ti\u00ean<\/strong><\/p>\n<p>Ng\u01b0\u1eddi thu\u00ea m\u1edbi mu\u1ed1n l\u1eafp \u0111\u1eb7t:<\/p>\n<ul>\n<li>M\u00e1y pha c\u00e0 ph\u00ea th\u01b0\u01a1ng m\u1ea1i (m\u1ea1ch chuy\u00ean d\u1ee5ng 20A)<\/li>\n<li>T\u1ee7 l\u1ea1nh d\u01b0\u1edbi qu\u1ea7y (2\u00d7 m\u1ea1ch 20A)<\/li>\n<li>Chi\u1ebfu s\u00e1ng b\u1ed5 sung (3\u00d7 m\u1ea1ch 15A)<\/li>\n<li>M\u1ea1ch chuy\u00ean d\u1ee5ng cho h\u1ec7 th\u1ed1ng POS (20A)<\/li>\n<\/ul>\n<p><strong>C\u00e1c m\u1ea1ch m\u1edbi c\u1ea7n thi\u1ebft:<\/strong> 7<\/p>\n<p><strong>V\u1ea5n \u0111\u1ec1:<\/strong> 22 m\u1ea1ch + 7 = 29 m\u1ea1ch. Ch\u1ec9 c\u00f3 30 ch\u1ed7 trong b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n. V\u1eeba \u0111\u1ee7.<\/p>\n<hr \/>\n<p><strong>N\u0103m 3: C\u1ea3i thi\u1ec7n m\u1eb7t b\u1eb1ng cho ng\u01b0\u1eddi thu\u00ea th\u1ee9 hai<\/strong><\/p>\n<p>Ng\u01b0\u1eddi thu\u00ea m\u1edf r\u1ed9ng sang d\u00e3y ph\u00f2ng li\u1ec1n k\u1ec1 (t\u0103ng tr\u01b0\u1edfng thu\u00ea), c\u1ea7n:<\/p>\n<ul>\n<li>M\u1edf r\u1ed9ng v\u00f9ng chi\u1ebfu s\u00e1ng (4 m\u1ea1ch)<\/li>\n<li>\u1ed4 c\u1eafm b\u1ed5 sung (3 m\u1ea1ch)<\/li>\n<li>Th\u00eam m\u1ed9t d\u00e0n HVAC cho kh\u00f4ng gian m\u1edf r\u1ed9ng (1 m\u1ea1ch)<\/li>\n<li>Thi\u1ebft b\u1ecb nh\u00e0 b\u1ebfp (3 m\u1ea1ch)<\/li>\n<\/ul>\n<p><strong>C\u00e1c m\u1ea1ch m\u1edbi c\u1ea7n thi\u1ebft:<\/strong> 11<\/p>\n<p><strong>V\u1ea5n \u0111\u1ec1:<\/strong> 29 + 11 = 40 m\u1ea1ch. B\u1ea3ng \u0111i\u1ec1u khi\u1ec3n \u0111\u00e3 v\u01b0\u1ee3t qu\u00e1 10 ch\u1ed7.<\/p>\n<p><strong>\u201cThu\u1ebf m\u1edf r\u1ed9ng\u201d \u0111\u1ebfn h\u1ea1n:<\/strong><\/p>\n<ul>\n<li>B\u1ea3ng ph\u00e2n ph\u1ed1i \u0111i\u1ec7n 400A m\u1edbi, 42 ch\u1ed7: $2,100<\/li>\n<li>Th\u00e1o d\u1ee1 b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n c\u0169 + l\u1eafp \u0111\u1eb7t: $1,800 nh\u00e2n c\u00f4ng<\/li>\n<li>L\u00e0m vi\u1ec7c ngo\u00e0i gi\u1edd (kh\u00f4ng th\u1ec3 t\u1eaft ho\u1ea1t \u0111\u1ed9ng b\u00e1n l\u1ebb trong gi\u1edd l\u00e0m vi\u1ec7c): +$600 ph\u1ee5 ph\u00ed<\/li>\n<li>Gi\u1ea5y ph\u00e9p\/ki\u1ec3m tra: $195<\/li>\n<li>\u0110i\u1ec1u ph\u1ed1i\/qu\u1ea3n l\u00fd d\u1ef1 \u00e1n: 8 gi\u1edd @ $95\/gi\u1edd = $760<\/li>\n<\/ul>\n<p><strong>T\u1ed5ng chi ph\u00ed thay th\u1ebf:<\/strong> $5,455<\/p>\n<p><strong>T\u1ed5ng chi ph\u00ed 3 n\u0103m:<\/strong> $1,200 (ban \u0111\u1ea7u) + $5,455 (thay th\u1ebf) = <strong>$6,655<\/strong><\/p>\n<p><strong>\u0110i\u1ec1u g\u00ec n\u00ean \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh ban \u0111\u1ea7u:<\/strong> B\u1ea3ng ph\u00e2n ph\u1ed1i \u0111i\u1ec7n 400A, 42 ch\u1ed7<\/p>\n<p><strong>Chi ph\u00ed n\u1ebfu ch\u1ec9 \u0111\u1ecbnh \u0111\u00fang:<\/strong><\/p>\n<ul>\n<li>Thi\u1ebft b\u1ecb: $1,650<\/li>\n<li>L\u1eafp \u0111\u1eb7t: $950<\/li>\n<li>T\u1ed5ng: $2,600<\/li>\n<\/ul>\n<p><strong>Thu\u1ebf m\u1edf r\u1ed9ng:<\/strong> $6,655 &#8211; $2,600 = <strong>$4,055 ti\u1ec1n ph\u1ea1t<\/strong> v\u00ec \u0111\u00e3 ch\u1ecdn \u201ct\u00f9y ch\u1ecdn ng\u00e2n s\u00e1ch\u201d<\/p>\n<p><strong>Chi ph\u00ed h\u00e0ng n\u0103m:<\/strong> $4,055 \u00f7 3 n\u0103m = <strong>$1,352\/n\u0103m<\/strong> ti\u1ec1n l\u00e3ng ph\u00ed<\/p>\n<p><strong>B\u00e0i h\u1ecdc:<\/strong> \u0110\u1ed1i v\u1edbi b\u1ea5t k\u1ef3 \u1ee9ng d\u1ee5ng th\u01b0\u01a1ng m\u1ea1i n\u00e0o c\u00f3 kh\u1ea3 n\u0103ng c\u1ea3i thi\u1ec7n m\u1eb7t b\u1eb1ng cho ng\u01b0\u1eddi thu\u00ea ho\u1eb7c thay \u0111\u1ed5i ng\u01b0\u1eddi s\u1eed d\u1ee5ng, <strong>h\u00e3y gi\u1ea3 \u0111\u1ecbnh s\u1ef1 t\u0103ng tr\u01b0\u1edfng s\u1ebd x\u1ea3y ra nhanh h\u01a1n d\u1ef1 ki\u1ebfn c\u1ee7a ch\u1ee7 s\u1edf h\u1eefu<\/strong>. \u201cV\u1ea5n \u0111\u1ec1 \u0111\u1ea7y \u0111\u1ee7 trong 2 n\u0103m\u201d l\u00e0 c\u00f3 th\u1eadt v\u00e0 \u201cThu\u1ebf m\u1edf r\u1ed9ng\u201d l\u00e0 r\u1ea5t \u0111au \u0111\u1edbn.<\/p>\n<h2>T\u1eeb Th\u1ebb \u0110\u1ecf \u0111\u1ebfn Tu\u00e2n Th\u1ee7 Quy Chu\u1ea9n<\/h2>\n<p>Thanh tra vi\u00ean \u0111\u00e3 g\u1eafn th\u1ebb \u0111\u1ecf cho vi\u1ec7c l\u1eafp \u0111\u1eb7t tr\u1ecb gi\u00e1 $15,000 \u0111\u00f3 kh\u00f4ng h\u1ec1 g\u00e2y kh\u00f3 d\u1ec5. \u00d4ng \u1ea5y \u0111ang th\u1ef1c thi NEC 110.9, 408.36 v\u00e0 110.24\u2014c\u00e1c ph\u1ea7n quy chu\u1ea9n t\u01b0\u01a1ng t\u1ef1 gi\u00fap c\u00e1c t\u00f2a nh\u00e0 kh\u00f4ng tr\u1edf th\u00e0nh nguy c\u01a1 h\u1ecfa ho\u1ea1n v\u00e0 thi\u1ebft b\u1ecb kh\u00f4ng ph\u00e1t n\u1ed5 trong \u0111i\u1ec1u ki\u1ec7n s\u1ef1 c\u1ed1.<\/p>\n<p>S\u1ef1 kh\u00e1c bi\u1ec7t gi\u1eefa m\u1ed9t cu\u1ed9c ki\u1ec3m tra kh\u00f4ng \u0111\u1ea1t v\u00e0 m\u1ed9t l\u1ea7n th\u00f4ng qua ngay l\u1ea7n \u0111\u1ea7u ti\u00ean l\u00e0 hi\u1ec3u r\u1eb1ng \u201ctrung t\u00e2m t\u1ea3i so v\u1edbi b\u1ea3ng ph\u00e2n ph\u1ed1i \u0111i\u1ec7n\u201d kh\u00f4ng ch\u1ec9 l\u00e0 so s\u00e1nh gi\u00e1 c\u1ea3. \u0110\u00f3 l\u00e0 m\u1ed9t quy\u1ebft \u0111\u1ecbnh l\u1ef1a ch\u1ecdn h\u1ec7 th\u1ed1ng li\u00ean quan \u0111\u1ebfn <strong>s\u00e1u y\u1ebfu t\u1ed1 quan tr\u1ecdng<\/strong>: t\u00ednh to\u00e1n t\u1ea3i v\u1edbi h\u1ec7 s\u1ed1 nh\u00e2n li\u00ean t\u1ee5c 125%, x\u00e1c \u0111\u1ecbnh d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n, l\u1eadp k\u1ebf ho\u1ea1ch t\u0103ng tr\u01b0\u1edfng, y\u00eau c\u1ea7u v\u1ec1 \u0111i\u1ec7n \u00e1p\/pha, th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt lo\u1ea1i b\u1ed9 ng\u1eaft m\u1ea1ch v\u00e0 tu\u00e2n th\u1ee7 m\u00f4i tr\u01b0\u1eddng.<\/p>\n<p>\u0110\u00e2y l\u00e0 danh s\u00e1ch ki\u1ec3m tra c\u00f3 h\u1ec7 th\u1ed1ng c\u1ee7a b\u1ea1n:<\/p>\n<ol>\n<li>T\u00ednh to\u00e1n t\u1ea3i th\u1ef1c theo NEC 215.2 (li\u00ean t\u1ee5c \u00d7 125% + kh\u00f4ng li\u00ean t\u1ee5c \u00d7 100%)<\/li>\n<li>X\u00e1c minh d\u00f2ng s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n v\u00e0 kh\u1edbp v\u1edbi \u0111\u1ecbnh m\u1ee9c ng\u1eafn m\u1ea1ch c\u1ee7a thi\u1ebft b\u1ecb (c\u1ea3nh gi\u00e1c v\u1edbi \u201cB\u1eaby M\u1eb7c \u0110\u1ecbnh 10kA\u201d)<\/li>\n<li>L\u1eadp k\u1ebf ho\u1ea1ch t\u0103ng tr\u01b0\u1edfng b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng ph\u00e2n t\u00edch m\u1eadt \u0111\u1ed9 m\u1ea1ch (ng\u0103n ch\u1eb7n \u201cV\u1ea5n \u0111\u1ec1 \u0111\u1ea7y \u0111\u1ee7 trong 2 n\u0103m\u201d)<\/li>\n<li>X\u00e1c nh\u1eadn y\u00eau c\u1ea7u m\u1ed9t pha so v\u1edbi ba pha (d\u1eebng c\u1ee9ng \u0111\u1ed1i v\u1edbi trung t\u00e2m t\u1ea3i \u1edf ba pha)<\/li>\n<li>Ch\u1ec9 \u0111\u1ecbnh c\u00e1ch l\u1eafp b\u1ed9 ng\u1eaft m\u1ea1ch ch\u00ednh x\u00e1c (b\u1eaft bu l\u00f4ng \u0111\u1ec3 c\u1ea5p ng\u01b0\u1ee3c theo NEC 408.36(D))<\/li>\n<li>Kh\u1edbp \u0111\u1ecbnh m\u1ee9c NEMA v\u1edbi m\u00f4i tr\u01b0\u1eddng v\u00e0 x\u00e1c minh c\u00e1c y\u00eau c\u1ea7u v\u1ec1 v\u1ecb tr\u00ed NEC 408.43<\/li>\n<\/ol>\n<p>Th\u1ef1c hi\u1ec7n \u0111\u00fang nh\u1eefng \u0111i\u1ec1u n\u00e0y v\u00e0 vi\u1ec7c l\u1eafp \u0111\u1eb7t c\u1ee7a b\u1ea1n s\u1ebd v\u01b0\u1ee3t qua ki\u1ec3m tra, ph\u1ee5c v\u1ee5 tu\u1ed5i th\u1ecd thi\u1ebft k\u1ebf c\u1ee7a t\u00f2a nh\u00e0 v\u00e0 tr\u00e1nh \u201cThu\u1ebf m\u1edf r\u1ed9ng\u201d.\u201d<\/p>\n<p>M\u1ed9t l\u01b0u \u00fd cu\u1ed1i c\u00f9ng: <strong>NEC 2023 \u0111\u00e3 gi\u1edbi thi\u1ec7u c\u00e1c y\u00eau c\u1ea7u m\u1edbi \u0111\u1ed1i v\u1edbi b\u1ea3ng \u0111i\u1ec7n thay th\u1ebf<\/strong> trong M\u1ee5c 408.9. N\u1ebfu b\u1ea1n \u0111ang trang b\u1ecb th\u00eam cho c\u00e1c l\u1eafp \u0111\u1eb7t hi\u1ec7n c\u00f3, b\u1ea1n hi\u1ec7n c\u00f3 c\u00e1c quy t\u1eafc c\u1ee5 th\u1ec3 v\u1ec1 c\u00e1c y\u00eau c\u1ea7u \u0111\u00e1nh gi\u00e1 t\u1ea1i ch\u1ed7 khi d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n v\u01b0\u1ee3t qu\u00e1 10kA v\u00e0 b\u1ea1n kh\u00f4ng s\u1eed d\u1ee5ng danh s\u00e1ch b\u1ea3ng \u0111i\u1ec7n k\u00edn. Th\u1eddi k\u1ef3 thay th\u1ebf b\u1ea3ng \u0111i\u1ec7n m\u1ed9t c\u00e1ch t\u00f9y ti\u1ec7n v\u00e0o c\u00e1c t\u1ee7 c\u0169 \u0111\u00e3 qua\u2014vi\u1ec7c \u0111\u00e1nh gi\u00e1 t\u1ea1i ch\u1ed7 b\u1edfi m\u1ed9t t\u1ed5 ch\u1ee9c \u0111\u1ee7 \u0111i\u1ec1u ki\u1ec7n hi\u1ec7n \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u trong nhi\u1ec1u tr\u01b0\u1eddng h\u1ee3p. H\u00e3y t\u00ednh y\u1ebfu t\u1ed1 n\u00e0y v\u00e0o chi ph\u00ed d\u1ef1 \u00e1n thay th\u1ebf c\u1ee7a b\u1ea1n.<\/p>\n<p><strong>S\u1eb5n s\u00e0ng ch\u1ec9 \u0111\u1ecbnh thi\u1ebft b\u1ecb ph\u00e2n ph\u1ed1i ph\u00f9 h\u1ee3p ngay t\u1eeb \u0111\u1ea7u?<\/strong> VIOX Electric s\u1ea3n xu\u1ea5t b\u1ea3ng \u0111i\u1ec7n v\u00e0 trung t\u00e2m t\u1ea3i tu\u00e2n th\u1ee7 NEC v\u1edbi danh s\u00e1ch UL 67 ho\u00e0n ch\u1ec9nh, \u0111\u1ecbnh m\u1ee9c d\u00f2ng \u0111i\u1ec7n s\u1ef1 c\u1ed1 c\u00f3 s\u1eb5n t\u1eeb 10kA \u0111\u1ebfn 100kA v\u00e0 h\u1ed7 tr\u1ee3 k\u1ef9 thu\u1eadt \u0111\u1ec3 x\u00e1c minh s\u1ef1 tu\u00e2n th\u1ee7 quy t\u1eafc tr\u01b0\u1edbc khi mua s\u1eafm. <a href=\"https:\/\/test.viox.com\/vi\/contact\/\">Li\u00ean h\u1ec7 v\u1edbi nh\u00f3m k\u1ef9 thu\u1eadt \u1ee9ng d\u1ee5ng c\u1ee7a ch\u00fang t\u00f4i<\/a> \u0111\u1ec3 xem x\u00e9t t\u00ednh to\u00e1n t\u1ea3i v\u00e0 h\u01b0\u1edbng d\u1eabn l\u1ef1a ch\u1ecdn b\u1ea3ng \u0111i\u1ec7n\u2014v\u00ec vi\u1ec7c v\u01b0\u1ee3t qua ki\u1ec3m tra kh\u00f4ng n\u00ean l\u00e0 m\u1ed9t canh b\u1ea1c.<\/p>\n<\/article>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>The permit&#8217;s approved. Installation&#8217;s complete. $15,000 invested.The electrical inspector arrives Tuesday morning, clipboard in hand, and walks straight to your newly installed distribution panel\u2014the one you spec&#8217;d as a load center because the price was right and the building seemed small enough. His pen hovers over the permit. &#8220;This won&#8217;t pass.&#8221; Red tag. Your commercial [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":20128,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-20121","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/posts\/20121","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/comments?post=20121"}],"version-history":[{"count":6,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/posts\/20121\/revisions"}],"predecessor-version":[{"id":20127,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/posts\/20121\/revisions\/20127"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/media\/20128"}],"wp:attachment":[{"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/media?parent=20121"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/categories?post=20121"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/test.viox.com\/vi\/wp-json\/wp\/v2\/tags?post=20121"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}