{"id":3312,"date":"2026-07-31T09:11:20","date_gmt":"2026-07-31T09:11:20","guid":{"rendered":"https:\/\/huyuglobal.com\/?p=3312"},"modified":"2026-07-31T09:11:22","modified_gmt":"2026-07-31T09:11:22","slug":"nec-requirements-for-wires-and-the-voltage-they-carry","status":"publish","type":"post","link":"https:\/\/huyuglobal.com\/vi\/blog\/nec-requirements-for-wires-and-the-voltage-they-carry\/","title":{"rendered":"C\u00e1c y\u00eau c\u1ea7u c\u1ee7a NEC \u0111\u1ed1i v\u1edbi d\u00e2y v\u00e0 \u0111i\u1ec7n \u00e1p m\u00e0 ch\u00fang mang theo"},"content":{"rendered":"<p>M\u1ed9t s\u1ef1 c\u1ed1 g\u1ea7n \u0111\u00e2y li\u00ean quan \u0111\u1ebfn m\u1ed9t nh\u00e0 th\u1ea7u \u1edf Illinois \u0111\u00e3 ch\u1ea1y c\u00e1p cho m\u1ed9t nh\u00e0 b\u1ebfp th\u01b0\u01a1ng m\u1ea1i m\u1edbi b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng d\u00e2y \u0111\u1ed3ng THHN c\u1ee1 10 cho m\u1ea1ch ba pha 30 ampe, 208 volt cho l\u00f2 \u0111\u1ed1i l\u01b0u. Lo\u1ea1i d\u00e2y d\u1eabn n\u00e0y \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 cho 600 volt. Bi\u1ec3u \u0111\u1ed3 ampacity c\u1ee7a NEC ph\u00ea duy\u1ec7t 35 ampe \u0111\u1ec3 s\u1eed d\u1ee5ng v\u1edbi d\u00e2y d\u1eabn n\u00e0y trong l\u1eafp \u0111\u1eb7t c\u1ee5 th\u1ec3. C\u00f3 v\u1ebb nh\u01b0 m\u1ecdi th\u1ee9 \u0111\u1ec1u \u0111\u00fang quy tr\u00ecnh, nh\u01b0ng thanh tra \u0111\u00e3 kh\u00f4ng ch\u1ea5p thu\u1eadn l\u1eafp \u0111\u1eb7t kh\u00f4ng ph\u1ea3i do k\u00edch th\u01b0\u1edbc d\u00e2y ho\u1eb7c \u0111\u00e1nh gi\u00e1 \u0111i\u1ec7n \u00e1p, m\u00e0 v\u00ec nh\u00e0 th\u1ea7u \u0111\u00e3 ch\u1ea1y d\u00e2y 208 volt trong c\u00f9ng m\u1ed9t \u1ed1ng d\u1eabn v\u1edbi m\u1ed9t s\u1ed1 m\u1ea1ch chi\u1ebfu s\u00e1ng nh\u00e1nh 120 volt m\u00e0 kh\u00f4ng c\u00f3 r\u00e0o c\u1ea3n v\u1eadt l\u00fd n\u00e0o. \u0110i\u1ec1u n\u00e0y vi ph\u1ea1m y\u00eau c\u1ea7u c\u1ee7a NEC n\u00f3i r\u1eb1ng c\u00e1c d\u00e2y c\u00f3 l\u1edbp \u0111i\u1ec7n \u00e1p kh\u00e1c nhau n\u00ean \u0111\u01b0\u1ee3c t\u00e1ch bi\u1ec7t tr\u1eeb khi t\u1ea5t c\u1ea3 \u0111\u1ec1u \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n cho \u0111i\u1ec7n \u00e1p t\u1ed1i \u0111a. \u0110\u1ec3 l\u00e0m cho vi\u1ec7c l\u1eafp \u0111\u1eb7t tu\u00e2n th\u1ee7, c\u1ea7n ph\u1ea3i l\u1ea5y ra c\u00e1c d\u00e2y c\u00f3 \u0111i\u1ec7n \u00e1p cao h\u01a1n v\u00e0 thay v\u00e0o \u0111\u00f3 s\u1eed d\u1ee5ng m\u1ed9t \u1ed1ng d\u1eabn ri\u00eang cho ch\u00fang. K\u1ebft lu\u1eadn ch\u00ednh l\u00e0 c\u1ed5 \u0111i\u1ec3n \u2014 vi\u1ec7c \u0111\u00e1p \u1ee9ng c\u00e1c y\u00eau c\u1ea7u c\u1ee7a NEC v\u1ec1 d\u00e2y d\u1eabn v\u00e0 \u0111i\u1ec7n \u00e1p kh\u00f4ng ch\u1ec9 \u0111\u01a1n gi\u1ea3n l\u00e0 xem ampacity v\u00e0 \u0111\u00e1nh gi\u00e1 c\u00e1ch \u0111i\u1ec7n. C\u00f3 s\u1ef1 t\u01b0\u01a1ng t\u00e1c gi\u1eefa \u0111i\u1ec7n \u00e1p, \u0111\u00e1nh gi\u00e1 c\u00e1ch \u0111i\u1ec7n, kho\u1ea3ng c\u00e1ch v\u00e0 kho\u1ea3ng c\u00e1ch an to\u00e0n. H\u01b0\u1edbng d\u1eabn n\u00e0y m\u00f4 t\u1ea3 c\u00e1c quy t\u1eafc c\u01a1 b\u1ea3n c\u1ee7a NEC li\u00ean k\u1ebft k\u00edch th\u01b0\u1edbc d\u00e2y v\u00e0 c\u00e1ch \u0111i\u1ec7n.<\/p>\n<blockquote><p><strong>T\u00f3m t\u1eaft:<\/strong>\u00a0NEC kh\u00f4ng ch\u1ee9a b\u1ea5t k\u1ef3 bi\u1ec3u \u0111\u1ed3 n\u00e0o ch\u1ec9 \u0111\u1ecbnh d\u00e2y n\u00e0o \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho m\u1ed7i m\u1ee9c \u0111i\u1ec7n \u00e1p. Thay v\u00e0o \u0111\u00f3, NEC tr\u00ecnh b\u00e0y m\u1ed9t lo\u1ea1t c\u00e1c th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt ph\u1ee9c t\u1ea1p li\u00ean quan \u0111\u1ebfn nhau m\u00f4 t\u1ea3 m\u1ed9t s\u1ed1 y\u1ebfu t\u1ed1 quan tr\u1ecdng \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn m\u1ed1i quan h\u1ec7 gi\u1eefa d\u00e2y d\u1eabn v\u00e0 \u0111i\u1ec7n \u00e1p m\u00e0 n\u00f3 mang. Trong s\u1ed1 c\u00e1c th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt ch\u00ednh n\u00e0y, ch\u00fang ta c\u00f3 th\u1ec3 th\u1ea5y \u0111\u1ecbnh m\u1ee9c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n (\u0110i\u1ec1u 310.4 c\u1ee7a NEC \u2014 y\u00eau c\u1ea7u t\u1ea5t c\u1ea3 c\u00e1c d\u00e2y d\u1eabn ph\u1ea3i \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n \u0111\u1ea7y \u0111\u1ee7 cho \u0111i\u1ec7n \u00e1p cao nh\u1ea5t c\u00f3 th\u1ec3 xu\u1ea5t hi\u1ec7n trong \u1ed1ng d\u1eabn ho\u1eb7c c\u00e1p v\u00e0 c\u00e1c d\u00e2y d\u1eabn thu\u1ed9c c\u00e1c l\u1edbp \u0111i\u1ec7n \u00e1p kh\u00e1c nhau ph\u1ea3i \u0111\u01b0\u1ee3c t\u00e1ch bi\u1ec7t v\u1edbi nhau tr\u1eeb khi \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n \u0111\u00fang c\u00e1ch), \u0111\u1ecbnh m\u1ee9c d\u00f2ng \u0111i\u1ec7n v\u00e0 nhi\u1ec7t \u0111\u1ed9 (\u0110i\u1ec1u 310.16 c\u1ee7a NEC v\u00e0 c\u00e1c b\u1ea3ng li\u00ean quan \u2014 x\u00e1c \u0111\u1ecbnh kh\u1ea3 n\u0103ng ch\u1ecbu t\u1ea3i c\u1ee7a d\u00e2y d\u1ef1a tr\u00ean k\u00edch th\u01b0\u1edbc d\u00e2y, \u0111\u1ecbnh m\u1ee9c nhi\u1ec7t \u0111\u1ed9 c\u00e1ch \u0111i\u1ec7n, nhi\u1ec7t \u0111\u1ed9 m\u00f4i tr\u01b0\u1eddng v\u00e0 s\u1ed1 l\u01b0\u1ee3ng d\u00e2y trong \u1ed1ng d\u1eabn v\u00e0 y\u00eau c\u1ea7u k\u00edch th\u01b0\u1edbc d\u00e2y \u0111\u01b0\u1ee3c t\u00ednh to\u00e1n \u0111\u1ec3 cung c\u1ea5p kh\u1ea3 n\u0103ng d\u00f2ng \u0111i\u1ec7n kh\u00f4ng nh\u1ecf h\u01a1n d\u00f2ng t\u1ea3i v\u00e0 \u0111\u1ecbnh m\u1ee9c c\u1ee7a b\u1ed9 ng\u1eaft m\u1ea1ch), s\u1ee5t \u00e1p (\u0110i\u1ec1u 210.19(A) c\u1ee7a NEC Ghi ch\u00fa K\u1ef9 thu\u1eadt s\u1ed1 4 y\u00eau c\u1ea7u kh\u00f4ng \u0111\u01b0\u1ee3c x\u1ea3y ra s\u1ee5t \u00e1p qu\u00e1 5% trong qu\u00e1 tr\u00ecnh v\u1eadn h\u00e0nh d\u00e2y tr\u00ean b\u1ea5t k\u1ef3 m\u1ea1ch nh\u00e1nh n\u00e0o v\u00e0 kh\u00f4ng qu\u00e1 3% trong m\u1ea1ch c\u1ea5p ngu\u1ed3n v\u00e0 2% trong d\u00e2y d\u1eabn) v\u00e0 nguy\u00ean t\u1eafc \u00e1p d\u1ee5ng 125% (\u0110i\u1ec1u 210.19(A)(1) c\u1ee7a NEC \u2014 quy \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc d\u00e2y ph\u1ea3i t\u01b0\u01a1ng \u1ee9ng v\u1edbi 125% t\u1ea3i li\u00ean t\u1ee5c c\u1ed9ng v\u1edbi 100% t\u1ea3i d\u1ef1 ki\u1ebfn s\u1eed d\u1ee5ng trong ho\u1ea1t \u0111\u1ed9ng kh\u00f4ng li\u00ean t\u1ee5c). T\u1ea5t c\u1ea3 c\u00e1c th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt n\u00eau tr\u00ean \u0111\u1ec1u c\u00f3 li\u00ean quan v\u1edbi nhau: v\u00ed d\u1ee5, m\u1ed9t d\u00e2y d\u1eabn tu\u00e2n th\u1ee7 ti\u00eau chu\u1ea9n c\u00e1ch \u0111i\u1ec7n c\u00f3 th\u1ec3 nh\u1ecf h\u01a1n so v\u1edbi y\u00eau c\u1ea7u v\u1ec1 \u0111\u1ecbnh m\u1ee9c d\u00f2ng \u0111i\u1ec7n v\u00e0\/ho\u1eb7c s\u1ee5t \u00e1p; t\u01b0\u01a1ng t\u1ef1, m\u1ed9t d\u00e2y d\u1eabn ph\u00f9 h\u1ee3p v\u1edbi ti\u00eau chu\u1ea9n k\u00edch th\u01b0\u1edbc c\u00f3 th\u1ec3 b\u1ecb l\u1eafp \u0111\u1eb7t sai n\u1ebfu n\u00f3 \u0111\u01b0\u1ee3c \u0111\u1eb7t trong \u1ed1ng d\u1eabn c\u00f9ng v\u1edbi c\u00e1c d\u00e2y d\u1eabn thu\u1ed9c ti\u00eau chu\u1ea9n \u0111i\u1ec7n \u00e1p kh\u00e1c.<\/p><\/blockquote>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3314\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/07\/The-Insulation-Voltage-Rating-The-First-and-Most-Fundamental-Requirement.webp\" alt=\"M\u1ee9c \u0110i\u1ec7n \u00c1p C\u00e1ch \u0110i\u1ec7n Y\u00eau C\u1ea7u \u0110\u1ea7u Ti\u00ean v\u00e0 C\u01a1 B\u1ea3n Nh\u1ea5t\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>\u0110\u1ecbnh m\u1ee9c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n: Y\u00eau c\u1ea7u \u0111\u1ea7u ti\u00ean v\u00e0 c\u01a1 b\u1ea3n nh\u1ea5t<\/h2>\n<p>T\u1ea5t c\u1ea3 c\u00e1c lo\u1ea1i d\u00e2y d\u1eabn \u0111\u01b0\u1ee3c s\u1ea3n xu\u1ea5t \u0111\u1ec3 \u0111i d\u00e2y b\u00ean trong c\u00e1c t\u00f2a nh\u00e0 \u0111\u1ec1u \u0111\u01b0\u1ee3c g\u00e1n m\u1ed9t \u0111\u1ecbnh m\u1ee9c \u0111i\u1ec7n \u00e1p \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh tr\u00ean l\u1edbp c\u00e1ch \u0111i\u1ec7n ho\u1eb7c v\u1ecf c\u00e1p. \u0110\u1ecbnh m\u1ee9c \u0111i\u1ec7n \u00e1p c\u00f3 ngh\u0129a l\u00e0 l\u1edbp c\u00e1ch \u0111i\u1ec7n c\u00f3 kh\u1ea3 n\u0103ng ch\u1ecbu \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh li\u00ean t\u1ee5c v\u00e0 \u0111\u00e2y l\u00e0 \u0111i\u1ec1u \u0111\u1ea7u ti\u00ean m\u00e0 th\u1ee3 \u0111i\u1ec7n ho\u1eb7c ki\u1ec3m tra vi\u00ean s\u1ebd xem x\u00e9t \u0111\u1ec3 ki\u1ec3m tra xem m\u1ed9t d\u00e2y d\u1eabn c\u1ee5 th\u1ec3 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u00e1p d\u1ee5ng cho m\u1ed9t m\u1ea1ch c\u1ee5 th\u1ec3 hay kh\u00f4ng. Theo th\u1ef1c ti\u1ec5n ti\u00eau chu\u1ea9n trong c\u00e1c c\u00f4ng tr\u00ecnh \u0111i\u1ec7n \u00e1p th\u1ea5p, c\u00e1c \u0111\u1ecbnh m\u1ee9c c\u00e1ch \u0111i\u1ec7n ti\u00eau chu\u1ea9n \u0111\u01b0\u1ee3c xem l\u00e0 300 V, 600 V v\u00e0 1.000 V. D\u00e2y d\u1eabn c\u00f3 kh\u1ea3 n\u0103ng ch\u1ecbu \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n 600 V, \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ed9ng r\u00e3i cho \u0111i d\u00e2y m\u1ea1ch nh\u00e1nh d\u00e2n d\u1ee5ng v\u00e0 th\u01b0\u01a1ng m\u1ea1i, bao g\u1ed3m c\u00e1c lo\u1ea1i d\u00e2y THHN, THWN v\u00e0 XHHW, ph\u00f9 h\u1ee3p cho vi\u1ec7c \u00e1p d\u1ee5ng cho b\u1ea5t k\u1ef3 lo\u1ea1i m\u1ea1ch n\u00e0o l\u00ean \u0111\u1ebfn 600 V. D\u00e2y d\u1eabn c\u00f3 kh\u1ea3 n\u0103ng ch\u1ecbu \u0111\u01b0\u1ee3c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n 300 V th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho \u0111i d\u00e2y thi\u1ebft b\u1ecb, d\u00e2y n\u1ed1i \u0111\u00e8n v\u00e0 m\u1ed9t s\u1ed1 c\u00e1p \u0111i\u1ec1u khi\u1ec3n v\u00e0 ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho c\u00e1c m\u1ea1ch s\u1eed d\u1ee5ng \u0111i\u1ec7n \u00e1p l\u00ean \u0111\u1ebfn 300 V.<\/p>\n<p>M\u1eb7c d\u00f9 quy t\u1eafc c\u1ee7a NEC, \u0111\u01b0\u1ee3c quy \u0111\u1ecbnh trong \u0110i\u1ec1u 310.4, c\u00f3 kh\u00e1i ni\u1ec7m \u0111\u01a1n gi\u1ea3n, nh\u01b0ng n\u00f3 c\u00f3 m\u1ed9t \u00fd ngh\u0129a \u0111\u1eb7c bi\u1ec7t m\u00e0 kh\u00f4ng ph\u1ea3i l\u00fac n\u00e0o c\u0169ng \u0111\u01b0\u1ee3c nh\u1eadn ra. V\u1ec1 b\u1ea3n ch\u1ea5t, t\u1ea5t c\u1ea3 c\u00e1c d\u00e2y d\u1eabn \u0111\u01b0\u1ee3c \u0111\u1eb7t trong \u1ed1ng d\u1eabn, c\u00e1p ho\u1eb7c h\u1ed9p b\u1ea3o v\u1ec7 ph\u1ea3i \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n ph\u00f9 h\u1ee3p v\u1edbi \u0111i\u1ec7n \u00e1p \u0111\u1ecbnh m\u1ee9c cao nh\u1ea5t c\u00f3 trong \u1ed1ng d\u1eabn, c\u00e1p ho\u1eb7c h\u1ed9p b\u1ea3o v\u1ec7 \u0111\u00f3. Do \u0111\u00f3, n\u1ebfu \u1ed1ng d\u1eabn ch\u1ee9a c\u00e1c d\u00e2y chi\u1ebfu s\u00e1ng 120 volt c\u0169ng nh\u01b0 c\u00e1c d\u00e2y \u0111\u1ed9ng c\u01a1 480 volt, th\u00ec t\u1ea5t c\u1ea3 c\u00e1c d\u00e2y d\u1eabn trong \u1ed1ng d\u1eabn ph\u1ea3i \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n theo \u0111i\u1ec7n \u00e1p \u00edt nh\u1ea5t l\u00e0 600 volt. L\u1edbp c\u00e1ch \u0111i\u1ec7n c\u1ee7a c\u00e1c d\u00e2y d\u1eabn 120 volt kh\u00f4ng th\u1ec3 ch\u1ec9 l\u00e0 c\u00e1ch \u0111i\u1ec7n 300 volt m\u1eb7c d\u00f9 c\u00e1c d\u00e2y d\u1eabn ch\u1ec9 c\u00f3 120 volt; c\u00e1c d\u00e2y d\u1eabn n\u00e0y n\u1eb1m c\u00f9ng v\u1edbi c\u00e1c d\u00e2y d\u1eabn \u0111i\u1ec7n \u00e1p cao h\u01a1n, v\u00e0 do \u0111\u00f3 t\u1ea5t c\u1ea3 c\u00e1c d\u00e2y d\u1eabn \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t trong c\u00f9ng m\u1ed9t \u1ed1ng d\u1eabn ph\u1ea3i \u0111\u01b0\u1ee3c \u0111\u1ecbnh m\u1ee9c cho \u0111i\u1ec7n \u00e1p t\u1ed1i \u0111a c\u00f3 trong h\u1ec7 th\u1ed1ng d\u00e2y d\u1eabn. NEC cung c\u1ea5p m\u1ed9t kh\u1ea3 n\u0103ng th\u1ee9 hai: c\u00e1c d\u00e2y d\u1eabn v\u1edbi \u0111i\u1ec7n \u00e1p kh\u00e1c nhau c\u00f3 th\u1ec3 chia s\u1ebb c\u00f9ng m\u1ed9t \u1ed1ng d\u1eabn n\u1ebfu ch\u00fang \u0111\u01b0\u1ee3c c\u00e1ch \u0111i\u1ec7n v\u1edbi nhau b\u1eb1ng c\u00e1c r\u00e0o c\u1ea3n kh\u00f4ng d\u1eabn \u0111i\u1ec7n, m\u1eb7c d\u00f9 \u0111i\u1ec1u n\u00e0y r\u1ea5t hi\u1ebfm khi thi\u1ebft b\u1ecb \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t tr\u00ean th\u1ef1c \u0111\u1ecba. Th\u1ef1c ti\u1ec5n ph\u1ed5 bi\u1ebfn l\u00e0 bao ph\u1ee7 h\u1ec7 th\u1ed1ng d\u00e2y d\u1eabn \u0111i\u1ec7n \u00e1p h\u1ed7n h\u1ee3p b\u1eb1ng c\u00e1c d\u00e2y d\u1eabn \u0111\u01b0\u1ee3c \u0111\u1ecbnh m\u1ee9c cho 600 volt, \u0111i\u1ec1u n\u00e0y gi\u1ea3i th\u00edch r\u00f5 nh\u1ea5t l\u00fd do t\u1ea1i sao c\u00e1c d\u00e2y d\u1eabn v\u1edbi \u0111\u1ecbnh m\u1ee9c n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho h\u1ea7u h\u1ebft c\u00e1c h\u1ec7 th\u1ed1ng d\u00e2y d\u1eabn c\u00f4ng nghi\u1ec7p v\u00e0 th\u01b0\u01a1ng m\u1ea1i. <a href=\"https:\/\/www.nfpa.org\" rel=\"nofollow noopener\" target=\"_blank\">Hi\u1ec7p h\u1ed9i B\u1ea3o v\u1ec7 Ch\u00e1y Qu\u1ed1c gia (NFPA)<\/a>, \u0111\u01a1n v\u1ecb xu\u1ea5t b\u1ea3n NEC, cung c\u1ea5p to\u00e0n v\u0103n \u0110i\u1ec1u 310 v\u00e0 c\u00e1c b\u1ea3ng li\u00ean quan \u0111\u1ecbnh ngh\u0129a c\u00e1c \u0111\u1ecbnh m\u1ee9c c\u00e1ch \u0111i\u1ec7n, ampacity v\u00e0 \u0111i\u1ec1u ki\u1ec7n l\u1eafp \u0111\u1eb7t cho t\u1eebng lo\u1ea1i d\u00e2y d\u1eabn.<\/p>\n<h2>Ampacity v\u00e0 K\u00edch th\u01b0\u1edbc D\u00e2y d\u1eabn: M\u1ed1i quan h\u1ec7 gi\u1eefa \u0110\u01b0\u1eddng k\u00ednh d\u00e2y, Nhi\u1ec7t \u0111\u1ed9 v\u00e0 D\u00f2ng \u0111i\u1ec7n<\/h2>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3315\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/07\/Ampacity-and-Conductor-Sizing-The-Relationship-Between-Wire-Gauge-Temperature-and-Current.webp\" alt=\"Ampacity v\u00e0 K\u00edch Th\u01b0\u1edbc D\u00e2y D\u1eabn M\u1ed1i Quan H\u1ec7 Gi\u1eefa C\u1ee1 D\u00e2y, Nhi\u1ec7t \u0110\u1ed9 v\u00e0 D\u00f2ng \u0110i\u1ec7n\" width=\"1448\" height=\"1086\" \/><\/p>\n<p>Trong m\u1ed9t d\u00e2y d\u1eabn, \u0111i\u1ec7n \u00e1p v\u1eabn l\u00e0 m\u1ed9t y\u1ebfu t\u1ed1 quan tr\u1ecdng, tuy nhi\u00ean, n\u00f3 kh\u00f4ng ph\u1ea3i l\u00e0 y\u1ebfu t\u1ed1 duy nh\u1ea5t quy\u1ebft \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn. H\u01a1n n\u1eefa, k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn ph\u1ea3i ph\u00f9 h\u1ee3p v\u1edbi d\u00f2ng \u0111i\u1ec7n y\u00eau c\u1ea7u b\u1edfi t\u1ea3i, v\u00e0 k\u00edch th\u01b0\u1edbc ph\u1ee5 thu\u1ed9c v\u00e0o c\u00e1c y\u1ebfu t\u1ed1 nh\u01b0 \u0111\u01b0\u1eddng k\u00ednh d\u00e2y d\u1eabn, \u0111\u1ecbnh m\u1ee9c nhi\u1ec7t \u0111\u1ed9 c\u00e1ch \u0111i\u1ec7n, \u0111i\u1ec1u ki\u1ec7n m\u00f4i tr\u01b0\u1eddng, c\u0169ng nh\u01b0 l\u01b0\u1ee3ng d\u00f2ng \u0111i\u1ec7n ch\u1ea1y trong \u1ed1ng d\u1eabn. B\u1ea3ng ampacity theo NEC \u2013 c\u1ee5 th\u1ec3 l\u00e0 B\u1ea3ng 310.16 \u2013 h\u1ed7 tr\u1ee3 t\u00ednh to\u00e1n l\u01b0\u1ee3ng d\u00f2ng \u0111i\u1ec7n t\u1ed1i \u0111a cho ph\u00e9p \u0111\u1ed1i v\u1edbi lo\u1ea1i d\u00e2y d\u1eabn d\u1ef1a tr\u00ean \u0111\u01b0\u1eddng k\u00ednh d\u00e2y. V\u00ed d\u1ee5, m\u1ed9t d\u00e2y d\u1eabn \u0111\u1ed3ng 12 AWG v\u1edbi l\u1edbp c\u00e1ch \u0111i\u1ec7n \u0111\u1ecbnh m\u1ee9c 75\u02daC c\u00f3 th\u1ec3 ch\u1ecbu \u0111\u01b0\u1ee3c 25 ampe (m\u1eb7c d\u00f9 NEC gi\u1edbi h\u1ea1n d\u00f2ng \u0111i\u1ec7n cho m\u1ea1ch n\u00e0y l\u00e0 20 ampe) do theo quy \u0111\u1ecbnh c\u1ee7a NEC, c\u00e1c d\u00e2y d\u1eabn nh\u1ecf d\u1ec5 g\u1eb7p v\u1ea5n \u0111\u1ec1 qu\u00e1 nhi\u1ec7t h\u01a1n. Trong b\u1ea3ng d\u01b0\u1edbi \u0111\u00e2y, c\u00e1c d\u1eef li\u1ec7u ampacity kh\u00e1c nhau \u0111\u01b0\u1ee3c t\u00f3m t\u1eaft cho c\u00e1c d\u00e2y d\u1eabn \u0111\u1ed3ng s\u1eed d\u1ee5ng trong h\u1ec7 th\u1ed1ng d\u00e2y d\u1eabn t\u00f2a nh\u00e0 theo ti\u00eau chu\u1ea9n \u0111\u1ecbnh m\u1ee9c nhi\u1ec7t \u0111\u1ed9 NEC (75 C).<\/p>\n<table>\n<thead>\n<tr>\n<th>K\u00edch th\u01b0\u1edbc D\u00e2y d\u1eabn (AWG, \u0110\u1ed3ng)<\/th>\n<th>Ampacity \u1edf 75\u00b0C (B\u1ea3ng 310.16)<\/th>\n<th>\u0110\u1ecbnh m\u1ee9c Thi\u1ebft b\u1ecb qu\u00e1 d\u00f2ng ti\u00eau chu\u1ea9n (NEC 240.4(D))<\/th>\n<th>\u1ee8ng d\u1ee5ng \u0111i\u1ec3n h\u00ecnh<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>14 AWG<\/strong><\/td>\n<td>20 A<\/td>\n<td>15 A<\/td>\n<td>M\u1ea1ch chi\u1ebfu s\u00e1ng v\u00e0 \u1ed5 c\u1eafm \u0111a n\u0103ng 15 ampe<\/td>\n<\/tr>\n<tr>\n<td><strong>12 AWG<\/strong><\/td>\n<td>25 A<\/td>\n<td>20 A<\/td>\n<td>M\u1ea1ch \u1ed5 c\u1eafm nh\u00e0 b\u1ebfp, gi\u1eb7t \u1ee7i v\u00e0 ph\u00f2ng t\u1eafm 20 ampe<\/td>\n<\/tr>\n<tr>\n<td><strong>10 AWG<\/strong><\/td>\n<td>35 A<\/td>\n<td>30 A<\/td>\n<td>M\u1ea1ch m\u00e1y s\u1ea5y 30 ampe, m\u00e1y \u0111i\u1ec1u h\u00f2a nh\u1ecf, b\u00ecnh n\u01b0\u1edbc n\u00f3ng \u0111i\u1ec7n<\/td>\n<\/tr>\n<tr>\n<td><strong>8 AWG<\/strong><\/td>\n<td>50 A<\/td>\n<td>40 A ho\u1eb7c 50 A (t\u00f9y thu\u1ed9c v\u00e0o t\u1ea3i v\u00e0 \u1ee9ng d\u1ee5ng)<\/td>\n<td>M\u1ea1ch ph\u1ea1m vi 40 amp ho\u1eb7c 50 amp, b\u1ed9 s\u1ea1c EV<\/td>\n<\/tr>\n<tr>\n<td><strong>6 AWG<\/strong><\/td>\n<td>65 A<\/td>\n<td>50 A ho\u1eb7c 60 A<\/td>\n<td>B\u1ed9 s\u1ea1c EV l\u1edbn h\u01a1n, b\u1ea3ng ph\u1ee5, b\u1ed3n t\u1eafm n\u01b0\u1edbc n\u00f3ng<\/td>\n<\/tr>\n<tr>\n<td><strong>4 AWG<\/strong><\/td>\n<td>85 A<\/td>\n<td>70 A ho\u1eb7c 80 A<\/td>\n<td>D\u00e2y c\u1ea5p cho b\u1ea3ng ph\u1ee5, thi\u1ebft b\u1ecb d\u00e2n d\u1ee5ng l\u1edbn<\/td>\n<\/tr>\n<tr>\n<td><strong>2 AWG<\/strong><\/td>\n<td>115 A<\/td>\n<td>100 A<\/td>\n<td>B\u1ea3ng ph\u1ee5 d\u00e2n d\u1ee5ng, l\u1ed1i v\u00e0o d\u1ecbch v\u1ee5 nh\u1ecf<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>C\u00e1c s\u1ed1 li\u1ec7u ampacity c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh d\u1ef1a tr\u00ean c\u00e1c y\u1ebfu t\u1ed1 m\u00f4i tr\u01b0\u1eddng v\u00e0 s\u1ed1 l\u01b0\u1ee3ng d\u00e2y d\u1eabn hi\u1ec7n di\u1ec7n trong \u1ed1ng d\u1eabn. Trong tr\u01b0\u1eddng h\u1ee3p d\u00e2y d\u1eabn \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong g\u00e1c m\u00e1i n\u00f3ng, n\u01a1i nhi\u1ec7t \u0111\u1ed9 m\u00f4i tr\u01b0\u1eddng v\u01b0\u1ee3t qu\u00e1 nhi\u1ec7t \u0111\u1ed9 tham chi\u1ebfu ti\u00eau chu\u1ea9n 30\u00b0C (86\u00b0F), n\u00f3 ph\u1ea3i \u0111\u01b0\u1ee3c gi\u1ea3m \u0111\u1ecbnh m\u1ee9c khi ampacity cho ph\u00e9p b\u1ecb gi\u1ea3m b\u1edfi c\u00e1c h\u1ec7 s\u1ed1 trong B\u1ea3ng 310.15(B)(1). Ngo\u00e0i ra, m\u1ed9t \u1ed1ng d\u1eabn c\u00f3 h\u01a1n ba d\u00e2y d\u1eabn mang d\u00f2ng \u0111i\u1ec7n n\u00ean \u0111\u01b0\u1ee3c gi\u1ea3m \u0111\u1ecbnh m\u1ee9c theo c\u00e1c s\u1ed1 li\u1ec7u \u0111\u01b0\u1ee3c cung c\u1ea5p trong B\u1ea3ng 310.15(C)(1). Do \u0111\u00f3, vi\u1ec7c gi\u1ea3m ampacity cho ph\u00e9p c\u1ee7a d\u00e2y d\u1eabn x\u1ea3y ra, v\u00e0 d\u00e2y nh\u01b0 v\u1eady c\u00f3 th\u1ec3 b\u1ecb k\u00edch th\u01b0\u1edbc sai cho m\u1ea1ch tr\u00ean nhi\u1ec7t \u0111\u1ed9. \u0110\u1ec3 \u0111\u01b0\u1ee3c tr\u1ee3 gi\u00fap v\u1edbi ph\u00e9p t\u00ednh c\u1ee5 th\u1ec3 cho b\u1ea5t k\u1ef3 m\u1ea1ch n\u00e0o, h\u01b0\u1edbng d\u1eabn c\u1ee7a ch\u00fang t\u00f4i v\u1ec1 <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/what-size-circuit-breaker-do-i-need\/\">k\u00edch th\u01b0\u1edbc c\u1ea7u dao b\u1ea1n c\u1ea7n<\/a> tr\u00ecnh b\u00e0y quy tr\u00ecnh d\u1ef1a tr\u00ean NEC cho c\u1ea3 t\u1ea3i chung v\u00e0 t\u1ea3i \u0111\u1ed9ng c\u01a1, bao g\u1ed3m c\u00e1c h\u1ec7 s\u1ed1 gi\u1ea3m \u0111\u1ecbnh m\u1ee9c \u00e1p d\u1ee5ng cho c\u00e1c l\u1eafp \u0111\u1eb7t b\u00f3 d\u00e2y v\u00e0 nhi\u1ec7t \u0111\u1ed9 cao.<\/p>\n<h2>S\u1ee5t \u00e1p: Khuy\u1ebfn ngh\u1ecb c\u1ee7a NEC tr\u1edf th\u00e0nh y\u00eau c\u1ea7u trong th\u1ef1c t\u1ebf<\/h2>\n<p>S\u1ee5t \u00e1p kh\u00f4ng ph\u1ea3i l\u00e0 y\u00eau c\u1ea7u b\u1eaft bu\u1ed9c ph\u1ea3i tu\u00e2n theo theo NEC; thay v\u00e0o \u0111\u00f3, n\u00f3 ch\u1ec9 l\u00e0 h\u01b0\u1edbng d\u1eabn chung m\u00e0 nhi\u1ec1u lo\u1ea1i d\u1ef1 \u00e1n tu\u00e2n theo. Ph\u1ea7n l\u1edbn, c\u00e1c k\u1ef9 s\u01b0 tu\u00e2n theo khuy\u1ebfn ngh\u1ecb s\u1ee5t \u00e1p c\u1ee7a NEC. Theo \u0110i\u1ec1u 210.19(A) Ghi ch\u00fa Th\u00f4ng tin s\u1ed1 4, NEC khuy\u1ebfn ngh\u1ecb r\u1eb1ng m\u1ea1ch nh\u00e1nh kh\u00f4ng n\u00ean c\u00f3 gi\u00e1 tr\u1ecb s\u1ee5t \u00e1p v\u01b0\u1ee3t qu\u00e1 5%, trong \u0111\u00f3 kh\u00f4ng n\u00ean c\u00f3 h\u01a1n 3% tr\u00ean d\u00e2y c\u1ea5p v\u00e0 t\u1ed1i \u0111a 2% tr\u00ean m\u1ea1ch nh\u00e1nh. H\u01b0\u1edbng d\u1eabn c\u1ee7a NEC n\u00eau r\u1eb1ng t\u1ea3i 120 volt n\u00ean nh\u1eadn ngu\u1ed3n \u0111i\u1ec7n l\u00ean \u0111\u1ebfn 114 volt. T\u01b0\u01a1ng t\u1ef1, trong tr\u01b0\u1eddng h\u1ee3p t\u1ea3i 240 v\u00e0 480 volt, c\u00e1c gi\u00e1 tr\u1ecb t\u01b0\u01a1ng \u1ee9ng \u0111\u01b0\u1ee3c cung c\u1ea5p l\u00e0 228 volt v\u00e0 456 volt.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3316\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/07\/Voltage-Drop-The-NECs-Recommendation-That-Becomes-a-Requirement-in-Practice.webp\" alt=\"S\u1ee5t \u00c1p Khuy\u1ebfn Ngh\u1ecb c\u1ee7a NEC Tr\u1edf Th\u00e0nh Y\u00eau C\u1ea7u Trong Th\u1ef1c Ti\u1ec5n\" width=\"1448\" height=\"1086\" \/><\/p>\n<p>S\u1ee5t \u00e1p \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi chi\u1ec1u d\u00e0i d\u00e2y d\u1eabn, k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn, l\u01b0\u1ee3ng d\u00f2ng \u0111i\u1ec7n ch\u1ea1y qua n\u00f3 v\u00e0 \u0111i\u1ec7n \u00e1p ngu\u1ed3n. D\u00e2y d\u1eabn c\u00f9ng lo\u1ea1i b\u1eb1ng \u0111\u1ed3ng c\u1ee1 12-gauge \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 mang 20 Ampe m\u00e0 kh\u00f4ng c\u00f3 s\u1ee5t \u00e1p quan s\u00e1t \u0111\u01b0\u1ee3c tr\u00ean kho\u1ea3ng c\u00e1ch 50 feet s\u1ebd tr\u1ea3i qua s\u1ee5t \u00e1p kho\u1ea3ng 5% khi kho\u1ea3ng c\u00e1ch t\u0103ng l\u00ean 200 feet, \u0111i\u1ec1u n\u00e0y l\u1edbn h\u01a1n m\u1ee9c ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c theo M\u00e3 \u0111i\u1ec7n Qu\u1ed1c gia v\u00e0 c\u00f3 th\u1ec3 d\u1eabn \u0111\u1ebfn m\u1ed9t s\u1ed1 v\u1ea5n \u0111\u1ec1 nh\u01b0 \u0111\u00e8n b\u1ecb m\u1edd, \u0111\u1ed9ng c\u01a1 qu\u00e1 nhi\u1ec7t v\u00e0 thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed ho\u1ea1t \u0111\u1ed9ng kh\u00f4ng \u0111\u00fang. V\u1ea5n \u0111\u1ec1 n\u00e0y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c gi\u1ea3i quy\u1ebft b\u1eb1ng c\u00e1ch t\u0103ng k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn, s\u1eed d\u1ee5ng d\u00e2y \u0111\u1ed3ng c\u1ee1 10-gauge ho\u1eb7c th\u1eadm ch\u00ed 8-gauge cho kho\u1ea3ng c\u00e1ch d\u00e0i, nh\u1eb1m \u0111\u1ea3m b\u1ea3o \u0111i\u1ec7n tr\u1edf \u0111\u1ee7 v\u00e0 ph\u1ea1m vi s\u1ee5t \u00e1p ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c. Trong b\u1ea3ng d\u01b0\u1edbi \u0111\u00e2y, c\u00e1c chi\u1ec1u d\u00e0i t\u1ed1i \u0111a \u0111\u00e3 n\u00eau c\u1ee7a c\u00e1c k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn v\u00e0 t\u1ea3i kh\u00e1c nhau \u0111\u01b0\u1ee3c cung c\u1ea5p.<\/p>\n<table>\n<thead>\n<tr>\n<th>K\u00edch th\u01b0\u1edbc D\u00e2y d\u1eabn (AWG, \u0110\u1ed3ng)<\/th>\n<th>D\u00f2ng t\u1ea3i<\/th>\n<th>Kho\u1ea3ng c\u00e1ch t\u1ed1i \u0111a x\u1ea5p x\u1ec9 cho s\u1ee5t \u00e1p 5% (M\u1ea1ch 120 V)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td><strong>14 AWG<\/strong><\/td>\n<td>15 A<\/td>\n<td>50 feet (15 m\u00e9t)<\/td>\n<\/tr>\n<tr>\n<td><strong>12 AWG<\/strong><\/td>\n<td>20 A<\/td>\n<td>60 feet (18 m\u00e9t)<\/td>\n<\/tr>\n<tr>\n<td><strong>10 AWG<\/strong><\/td>\n<td>30 A<\/td>\n<td>70 feet (21 m\u00e9t)<\/td>\n<\/tr>\n<tr>\n<td><strong>8 AWG<\/strong><\/td>\n<td>50 A<\/td>\n<td>75 feet (23 m\u00e9t)<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Nh\u1eefng kho\u1ea3ng c\u00e1ch n\u00e0y l\u00e0 g\u1ea7n \u0111\u00fang v\u00e0 n\u00ean \u0111\u01b0\u1ee3c t\u00ednh to\u00e1n ch\u00ednh x\u00e1c cho vi\u1ec7c l\u1eafp \u0111\u1eb7t c\u1ee5 th\u1ec3, s\u1eed d\u1ee5ng d\u00f2ng t\u1ea3i th\u1ef1c t\u1ebf, chi\u1ec1u d\u00e0i d\u00e2y d\u1eabn th\u1ef1c t\u1ebf v\u00e0 c\u00f4ng th\u1ee9c s\u1ee5t \u00e1p NEC \u00e1p d\u1ee5ng. C\u00e1c c\u00f4ng c\u1ee5 t\u00ednh tr\u1ef1c tuy\u1ebfn v\u00e0 \u1ee9ng d\u1ee5ng di \u0111\u1ed9ng, nhi\u1ec1u trong s\u1ed1 \u0111\u00f3 \u0111\u01b0\u1ee3c tham kh\u1ea3o b\u1edfi c\u00e1c t\u1ed5 ch\u1ee9c ng\u00e0nh nh\u01b0 <a href=\"https:\/\/www.ecmag.com\" rel=\"nofollow noopener\" target=\"_blank\">T\u1ea1p ch\u00ed Nh\u00e0 th\u1ea7u \u0110i\u1ec7n<\/a>, cung c\u1ea5p m\u1ed9t c\u00e1ch thu\u1eadn ti\u1ec7n \u0111\u1ec3 th\u1ef1c hi\u1ec7n c\u00e1c ph\u00e9p t\u00ednh n\u00e0y t\u1ea1i hi\u1ec7n tr\u01b0\u1eddng, nh\u01b0ng c\u00f4ng th\u1ee9c c\u01a1 b\u1ea3n \u2014 Vd = (2 \u00d7 L \u00d7 I \u00d7 R) \/ 1.000 cho c\u00e1c m\u1ea1ch \u0111\u01a1n pha, trong \u0111\u00f3 R l\u00e0 \u0111i\u1ec7n tr\u1edf c\u1ee7a d\u00e2y d\u1eabn tr\u00ean m\u1ed7i 1.000 feet theo B\u1ea3ng 8 Ch\u01b0\u01a1ng 9 c\u1ee7a NEC \u2014 l\u00e0 \u0111\u01a1n gi\u1ea3n v\u00e0 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u00ednh b\u1eb1ng m\u00e1y t\u00ednh k\u1ef9 thu\u1eadt ti\u00eau chu\u1ea9n.<\/p>\n<h2>Quy t\u1eafc 125% cho T\u1ea3i Li\u00ean T\u1ee5c: K\u00edch Th\u01b0\u1edbc D\u00e2y D\u1eabn cho \u0110\u01b0\u1eddng D\u00e0i<\/h2>\n<p>Quy t\u1eafc 125% c\u1ee7a NEC l\u00e0 m\u1ed9t trong nh\u1eefng quy \u0111\u1ecbnh th\u01b0\u1eddng b\u1ecb hi\u1ec3u sai trong b\u1ed9 quy chu\u1ea9n. N\u00f3 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn c\u1ea7n s\u1eed d\u1ee5ng trong m\u1ed9t m\u1ea1ch \u0111i\u1ec7n. N\u00f3i \u0111\u01a1n gi\u1ea3n, t\u1ea3i li\u00ean t\u1ee5c \u0111\u01b0\u1ee3c m\u00f4 t\u1ea3 trong NEC l\u00e0 lo\u1ea1i t\u1ea3i ho\u1ea1t \u0111\u1ed9ng trong \u00edt nh\u1ea5t 3 gi\u1edd. Trong tr\u01b0\u1eddng h\u1ee3p n\u00e0y, d\u00e2y d\u1eabn s\u1eed d\u1ee5ng cho m\u1ea1ch ph\u1ea3i \u0111\u01b0\u1ee3c t\u00ednh d\u1ef1a tr\u00ean 125% c\u1ee7a t\u1ea3i li\u00ean t\u1ee5c c\u00f9ng v\u1edbi 100% c\u1ee7a t\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c. V\u00ed d\u1ee5, n\u1ebfu ch\u00fang ta c\u00f3 m\u1ed9t m\u1ea1ch v\u1edbi t\u1ea3i li\u00ean t\u1ee5c 16A (v\u00ed d\u1ee5: b\u00ecnh n\u01b0\u1edbc n\u00f3ng), n\u00f3 s\u1ebd t\u1ea1o ra \u0111\u1ecbnh m\u1ee9c 20A \u2014 16A * 1.25 = 20A. \u0110i\u1ec1u n\u00e0y cho th\u1ea5y d\u00e2y d\u1eabn \u0111\u1ed3ng c\u1ee1 12 l\u00e0 d\u00e2y nh\u1ecf nh\u1ea5t c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng cho t\u1ea3i nh\u01b0 v\u1eady. \u0110\u1ec3 tham kh\u1ea3o, d\u00e2y \u0111\u1ed3ng c\u1ee1 14 s\u1ebd qu\u00e1 nh\u1ecf v\u00ec n\u00f3 ch\u1ec9 c\u00f3 kh\u1ea3 n\u0103ng ch\u1ecbu 15A. Ngo\u00e0i ra, quy t\u1eafc n\u00e0y \u00e1p d\u1ee5ng cho thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng: c\u1ea7u dao c\u0169ng \u0111\u01b0\u1ee3c k\u00edch th\u01b0\u1edbc theo 125% c\u1ee7a t\u1ea3i. V\u00ec v\u1eady, v\u00ed d\u1ee5 trong tr\u01b0\u1eddng h\u1ee3p 16A c\u1ee7a ch\u00fang ta, ch\u00fang ta s\u1ebd ph\u1ea3i s\u1eed d\u1ee5ng c\u1ea7u dao 20A. \u0110\u00f3 l\u00e0 l\u00fd do t\u1ea1i sao nhi\u1ec1u m\u1ea1ch \u0111i\u1ec7n d\u00e2n d\u1ee5ng (\u0111\u1eb7c bi\u1ec7t l\u00e0 h\u1ec7 th\u1ed1ng s\u01b0\u1edfi nh\u00e0, m\u1ea1ch chi\u1ebfu s\u00e1ng b\u00ecnh th\u01b0\u1eddng trong c\u00e1c t\u00f2a nh\u00e0 v\u00e0 trung t\u00e2m d\u1eef li\u1ec7u) s\u1eed d\u1ee5ng m\u1ea1ch 20A v\u1edbi d\u00e2y c\u1ee1 12 thay v\u00ec tu\u00e2n th\u1ee7 quy chu\u1ea9n v\u00ec quy chu\u1ea9n y\u00eau c\u1ea7u nh\u01b0 v\u1eady v\u00e0 n\u00f3 b\u1ea3o v\u1ec7 d\u00e2y kh\u1ecfi nhi\u1ec7t sinh ra do s\u1eed d\u1ee5ng li\u00ean t\u1ee5c.<span style=\"color: #333333; font-size: 16px; font-weight: 400;\"> The \u2192 C\u00e1i <\/span><a style=\"font-size: 16px; font-weight: 400;\" href=\"https:\/\/www.ecmag.com\" rel=\"nofollow noopener\" target=\"_blank\">T\u1ea1p ch\u00ed Nh\u00e0 th\u1ea7u \u0110i\u1ec7n<\/a><span style=\"color: #333333; font-size: 16px; font-weight: 400;\"> v\u00e0 <\/span><a style=\"font-size: 16px; font-weight: 400;\" href=\"https:\/\/www.ul.com\" rel=\"nofollow noopener\" target=\"_blank\">UL<\/a><span style=\"color: #333333; font-size: 16px; font-weight: 400;\"> cung c\u1ea5p h\u01b0\u1edbng d\u1eabn chi ti\u1ebft v\u1ec1 vi\u1ec7c \u00e1p d\u1ee5ng quy t\u1eafc 125% trong c\u1ea3 l\u1eafp \u0111\u1eb7t d\u00e2n d\u1ee5ng v\u00e0 th\u01b0\u01a1ng m\u1ea1i.<\/span><\/p>\n<h2>Quy t\u1eafc 83%: Khi D\u00e2y D\u1eabn \u0110\u1ea7u V\u00e0o D\u1ecbch V\u1ee5 \u0110\u01b0\u1ee3c K\u00edch Th\u01b0\u1edbc Kh\u00e1c Nhau<\/h2>\n<p>Quy t\u1eafc 83% c\u1ee7a NEC l\u00e0 m\u1ed9t quy t\u1eafc quan tr\u1ecdng \u0111\u1ed1i v\u1edbi d\u00e2y d\u1eabn d\u1ecbch v\u1ee5 v\u00e0o nh\u00e0 \u1edf d\u00e2n d\u1ee5ng. Theo \u0110i\u1ec1u 310.12(A) c\u1ee7a NEC, d\u00e2y d\u1eabn d\u1ecbch v\u1ee5 v\u00e0o cho m\u1ed9t c\u0103n nh\u00e0 \u0111\u01a1n l\u1ebb c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u00ednh to\u00e1n theo 83% c\u1ee7a \u0111\u1ecbnh m\u1ee9c d\u1ecbch v\u1ee5, \u0111i\u1ec1u n\u00e0y kh\u00e1c v\u1edbi th\u1ef1c ti\u1ec5n th\u00f4ng th\u01b0\u1eddng khi d\u1ecbch v\u1ee5 d\u00e2n d\u1ee5ng 200 ampe \u0111\u01b0\u1ee3c t\u00ednh d\u1ef1a tr\u00ean y\u00eau c\u1ea7u t\u1ea3i \u0111\u1ea7y \u0111\u1ee7 nh\u01b0 \u0111\u1ed1i v\u1edbi d\u1ecbch v\u1ee5 th\u01b0\u01a1ng m\u1ea1i 200 ampe. Quy t\u1eafc 83% xem x\u00e9t t\u00ednh \u0111a d\u1ea1ng c\u1ee7a ngu\u1ed3n cung c\u1ea5p t\u1ea3i \u0111i\u1ec7n trong nh\u00e0, theo \u0111\u00f3 kh\u00f4ng c\u00f3 kh\u1ea3 n\u0103ng t\u1ea5t c\u1ea3 c\u00e1c thi\u1ebft b\u1ecb, \u0111\u00e8n v\u00e0 \u1ed5 c\u1eafm \u0111ang s\u1eed d\u1ee5ng \u0111\u1ec1u ho\u1ea1t \u0111\u1ed9ng \u1edf t\u1ea3i \u0111\u1ea7y \u0111\u1ee7. Do \u0111\u00f3, d\u1ecbch v\u1ee5 200 ampe c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng b\u1eb1ng d\u00e2y \u0111\u1ed3ng 2\/0 AWG, c\u00f3 th\u1ec3 cung c\u1ea5p d\u00f2ng \u0111i\u1ec7n v\u1edbi m\u1ee9c 175 ampe \u1edf nhi\u1ec7t \u0111\u1ed9 75\u00b0C, kh\u00e1c v\u1edbi d\u00e2y \u0111\u1ed3ng 3\/0 AWG s\u1ebd \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong h\u1ec7 th\u1ed1ng th\u01b0\u01a1ng m\u1ea1i 200 ampe. Th\u00eam v\u00e0o \u0111\u00f3, quy \u0111\u1ecbnh 83% ch\u1ec9 \u00e1p d\u1ee5ng cho d\u00e2y d\u1eabn d\u1ecbch v\u1ee5 v\u00e0o, l\u00e0 c\u00e1p k\u1ebft n\u1ed1i gi\u1eefa \u0111i\u1ec3m k\u1ebft n\u1ed1i ti\u1ec7n \u00edch v\u00e0 c\u00f4ng t\u1eafc ng\u1eaft ch\u00ednh c\u1ee7a nh\u00e0, nh\u01b0ng kh\u00f4ng \u00e1p d\u1ee5ng cho d\u00e2y d\u1eabn c\u1ea5p ngu\u1ed3n, d\u00e2y d\u1eabn m\u1ea1ch nh\u00e1nh ho\u1eb7c b\u1ea5t k\u1ef3 d\u1ecbch v\u1ee5 n\u00e0o kh\u00e1c \u1edf c\u00e1c d\u1ecbch v\u1ee5 h\u1ea1 l\u01b0u. H\u01a1n n\u1eefa, quy t\u1eafc 83% ch\u1ec9 \u00e1p d\u1ee5ng cho nh\u00e0 \u0111\u01a1n l\u1ebb v\u00e0 s\u1ebd h\u1ee3p l\u00fd khi t\u1ea5t c\u1ea3 c\u00e1c l\u0129nh v\u1ef1c kh\u00e1c c\u00f3 d\u00e2y d\u1eabn d\u1ecbch v\u1ee5 \u0111\u01b0\u1ee3c t\u00ednh to\u00e1n d\u1ef1a tr\u00ean y\u00eau c\u1ea7u t\u1ea3i v\u00e0 \u0111\u1ecbnh m\u1ee9c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3317\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/07\/The-83-Rule.webp\" alt=\"Quy t\u1eafc 83%\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>C\u00e1ch t\u1ea5t c\u1ea3 c\u00e1c quy t\u1eafc n\u00e0y t\u01b0\u01a1ng t\u00e1c: M\u1ed9t v\u00ed d\u1ee5 th\u1ef1c t\u1ebf<\/h2>\n<p>C\u00e1c th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt c\u1ee7a NEC li\u00ean quan \u0111\u1ebfn d\u00e2y d\u1eabn v\u00e0 m\u1ee9c \u0111i\u1ec7n \u00e1p c\u1ee7a ch\u00fang l\u00e0 c\u00e1c quy t\u1eafc li\u00ean quan ch\u1eb7t ch\u1ebd m\u00e0 m\u1ed9t d\u00e2y d\u1eabn \u0111\u01a1n ph\u1ea3i \u0111\u00e1p \u1ee9ng t\u1ea5t c\u1ea3. V\u00ed d\u1ee5, m\u1ed9t nh\u00e0 s\u1ea3n xu\u1ea5t c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng lo\u1ea1i m\u1ea1ch \u0111\u1ed9ng c\u01a1 ba pha v\u1edbi \u0111i\u1ec7n \u00e1p 480 volt v\u00e0 d\u00f2ng \u0111i\u1ec7n 30 ampe. D\u00e2y d\u1eabn ph\u1ea3i c\u00f3 \u0111\u1ecbnh m\u1ee9c c\u00e1ch \u0111i\u1ec7n t\u1ed1i thi\u1ec3u l\u00e0 600 volt v\u00ec \u0111i\u1ec7n \u00e1p 480 volt li\u00ean quan \u0111\u1ebfn h\u1ec7 th\u1ed1ng \u0111i\u1ec7n \u00e1p th\u1ea5p y\u00eau c\u1ea7u d\u00e2y d\u1eabn c\u00f3 c\u00e1ch \u0111i\u1ec7n 600 volt. D\u00e2y d\u1eabn ph\u1ea3i \u0111\u00e1p \u1ee9ng y\u00eau c\u1ea7u v\u1ec1 k\u00edch th\u01b0\u1edbc d\u00e2y ph\u1ea3i b\u1eb1ng ho\u1eb7c l\u1edbn h\u01a1n d\u00f2ng \u0111i\u1ec7n c\u1ee7a \u0111\u1ed9ng c\u01a1 khi n\u00f3 ho\u1ea1t \u0111\u1ed9ng \u0111\u1ea7y t\u1ea3i. \u0110\u1ed1i v\u1edbi \u0111\u1ed9ng c\u01a1 ch\u1ea1y \u1edf d\u00f2ng 30 ampe v\u00e0 \u0111i\u1ec7n \u00e1p 480 volt, d\u00e2y d\u1eabn c\u00f3 th\u1ec3 l\u00e0 d\u00e2y \u0111\u1ed3ng #10. Tuy nhi\u00ean, do quy \u0111\u1ecbnh c\u1ee5 th\u1ec3 c\u1ee7a NEC v\u1ec1 m\u1ea1ch \u0111\u1ed9ng c\u01a1 y\u00eau c\u1ea7u h\u1ec7 th\u1ed1ng b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng ph\u1ea3i ch\u1ecbu \u0111\u01b0\u1ee3c 125% c\u1ee7a d\u00f2ng \u0111i\u1ec7n t\u1ea3i \u0111\u1ea7y \u0111\u1ee7 c\u1ee7a \u0111\u1ed9ng c\u01a1 (khi s\u1eed d\u1ee5ng v\u1edbi \u0111\u1ed9ng c\u01a1 l\u00e0m vi\u1ec7c li\u00ean t\u1ee5c), k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn c\u00f3 th\u1ec3 l\u1edbn h\u01a1n d\u00e2y \u0111\u1ed3ng #10. H\u01a1n n\u1eefa, d\u00e2y d\u1eabn c\u0169ng ph\u1ea3i \u0111\u01b0\u1ee3c gi\u1ea3m \u0111\u1ecbnh m\u1ee9c trong tr\u01b0\u1eddng h\u1ee3p \u0111i\u1ec1u ki\u1ec7n th\u1eddi ti\u1ebft n\u00f3ng; v\u00ed d\u1ee5, tr\u1ea7n nh\u00e0 m\u00e1y c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c gi\u1ea3m \u0111\u1ecbnh m\u1ee9c v\u00e0o m\u00f9a h\u00e8 \u0111\u1ec3 t\u0103ng k\u00edch th\u01b0\u1edbc d\u00e2y c\u1ea7n thi\u1ebft. K\u00edch th\u01b0\u1edbc d\u00e2y c\u0169ng ph\u1ea3i \u0111\u01b0\u1ee3c ki\u1ec3m tra li\u00ean quan \u0111\u1ebfn v\u1ea5n \u0111\u1ec1 s\u1ee5t \u00e1p; v\u00ed d\u1ee5, d\u00e2y d\u00e0i 300 feet ch\u1ea1y \u1edf \u0111i\u1ec7n \u00e1p 480 volt c\u00f3 th\u1ec3 l\u00e0 d\u00e2y #8 ho\u1eb7c #6 t\u00f9y thu\u1ed9c v\u00e0o c\u00e1c gi\u1edbi h\u1ea1n do s\u1ee5t \u00e1p \u00e1p \u0111\u1eb7t. D\u00e2y d\u1eabn c\u0169ng c\u1ea7n ph\u1ea3i chia s\u1ebb h\u1ec7 th\u1ed1ng v\u1edbi c\u00e1c d\u00e2y c\u00f3 c\u00f9ng \u0111\u1ecbnh m\u1ee9c c\u00e1ch \u0111i\u1ec7n \u0111i\u1ec7n t\u1eed l\u1edbn h\u01a1n 600 volt. D\u00e2y d\u1eabn s\u1eed d\u1ee5ng cho m\u1ed9t \u0111\u1ed9ng c\u01a1 ph\u1ea3i \u0111\u00e1p \u1ee9ng t\u1ea5t c\u1ea3 c\u00e1c y\u00eau c\u1ea7u kh\u00e1c nhau n\u00e0y.<\/p>\n<h2>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n<h3>Quy t\u1eafc 125% trong NEC l\u00e0 g\u00ec?<\/h3>\n<p>Theo \u0110i\u1ec1u 210.19(A)(1) c\u1ee7a NEC, c\u00e1c d\u00e2y d\u1eabn v\u00e0 thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng ph\u1ea3i c\u00f3 k\u00edch th\u01b0\u1edbc b\u1eb1ng 125% c\u1ee7a t\u1ea3i li\u00ean t\u1ee5c c\u1ed9ng v\u1edbi 100% c\u1ee7a t\u1ea3i kh\u00f4ng li\u00ean t\u1ee5c \u0111\u1ed1i v\u1edbi t\u1ea3i li\u00ean t\u1ee5c l\u00e0 t\u1ea3i ho\u1ea1t \u0111\u1ed9ng trong ba gi\u1edd tr\u1edf l\u00ean. Do \u0111\u00f3, \u0111\u1ed1i v\u1edbi t\u1ea3i li\u00ean t\u1ee5c 16 ampe, c\u00e1c d\u00e2y d\u1eabn ph\u1ea3i c\u00f3 k\u00edch th\u01b0\u1edbc t\u01b0\u01a1ng \u0111\u01b0\u01a1ng 20 ampe v\u00e0 m\u1ed9t b\u1ed9 ng\u1eaft m\u1ea1ch 20 ampe. Quy t\u1eafc n\u00e0y gi\u00fap duy tr\u00ec an to\u00e0n nhi\u1ec7t b\u1eb1ng c\u00e1ch ng\u0103n ng\u1eeba d\u00e2y d\u1eabn b\u1ecb qu\u00e1 nhi\u1ec7t khi ch\u1ea1y li\u00ean t\u1ee5c trong th\u1eddi gian d\u00e0i.<\/p>\n<h3>L\u00e0m th\u1ebf n\u00e0o \u0111\u1ec3 x\u00e1c \u0111\u1ecbnh \u0111i\u1ec7n \u00e1p \u0111i v\u00e0o d\u00e2y d\u1eabn?<\/h3>\n<p>\u0110\u1ec3 \u0111o \u0111i\u1ec7n \u00e1p tr\u00ean m\u1ed9t d\u00e2y d\u1eabn, s\u1eed d\u1ee5ng \u0111\u1ed3ng h\u1ed3 v\u1ea1n n\u0103ng k\u1ef9 thu\u1eadt s\u1ed1 \u0111\u01b0\u1ee3c \u0111i\u1ec1u ch\u1ec9nh \u0111\u1ec3 \u0111o \u0111i\u1ec7n \u00e1p AC v\u1edbi c\u00e1c \u0111\u1ea7u d\u00f2 \u0111o \u0111\u01b0\u1ee3c \u0111\u1eb7t sao cho m\u1ed9t \u0111\u1ea7u k\u1ebft n\u1ed1i v\u1edbi d\u00e2y d\u1eabn trong khi \u0111\u1ea7u kia \u0111\u01b0\u1ee3c g\u1eafn v\u00e0o d\u00e2y n\u1ed1i \u0111\u1ea5t c\u1ee7a m\u1ea1ch. \u0110i\u1ec7n \u00e1p c\u1ee7a d\u00e2y d\u1eabn ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c \u0111o khi d\u00e2y d\u1eabn \u0111ang c\u00f3 \u0111i\u1ec7n, v\u00e0 vi\u1ec7c \u0111o ch\u1ec9 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi m\u1ed9t th\u1ee3 \u0111i\u1ec7n c\u00f3 ch\u1ee9ng nh\u1eadn s\u1eed d\u1ee5ng thi\u1ebft b\u1ecb ki\u1ec3m tra ph\u00f9 h\u1ee3p c\u0169ng nh\u01b0 trang b\u1ecb an to\u00e0n. \u0110i\u1ec7n \u00e1p m\u00e0 d\u00e2y d\u1eabn c\u00f3 th\u1ec3 ch\u1ecbu \u0111\u01b0\u1ee3c \u0111\u01b0\u1ee3c ghi tr\u00ean l\u1edbp c\u00e1ch \u0111i\u1ec7n c\u1ee7a n\u00f3, th\u01b0\u1eddng l\u00e0 300 ho\u1eb7c 600 volt \u0111\u1ed1i v\u1edbi c\u00e1ch \u0111i\u1ec7n d\u00e2y d\u1eabn x\u00e2y d\u1ef1ng, m\u1eb7c d\u00f9 \u0111i\u1ec7n \u00e1p n\u00e0y kh\u00f4ng n\u00ean b\u1ecb nh\u1ea7m l\u1eabn v\u1edbi \u0111i\u1ec7n \u00e1p th\u1ef1c t\u1ebf c\u00f3 tr\u00ean d\u00e2y d\u1eabn t\u1ea1i th\u1eddi \u0111i\u1ec3m \u0111o.<\/p>\n<h3>Quy t\u1eafc gi\u1ea3m \u0111i\u1ec7n \u00e1p 5% trong NEC l\u00e0 g\u00ec?<\/h3>\n<p>Theo h\u01b0\u1edbng d\u1eabn \u0111\u01b0\u1ee3c tr\u00ecnh b\u00e0y trong \u0110i\u1ec1u 210.19(A) Ghi ch\u00fa Th\u00f4ng tin s\u1ed1 4 c\u1ee7a B\u1ed9 Quy t\u1eafc \u0110i\u1ec7n Qu\u1ed1c gia (NEC), khuy\u1ebfn c\u00e1o r\u1eb1ng t\u1ed5ng m\u1ee9c gi\u1ea3m \u0111i\u1ec7n \u00e1p t\u1ed1i \u0111a trong m\u1ea1ch nh\u00e1nh kh\u00f4ng v\u01b0\u1ee3t qu\u00e1 5% c\u1ee7a \u0111i\u1ec7n \u00e1p cung c\u1ea5p, v\u00e0 \u0111i\u1ec1u n\u00e0y n\u00ean bao g\u1ed3m gi\u1ea3m \u0111i\u1ec7n \u00e1p c\u1ee7a d\u00e2y c\u1ea5p ngu\u1ed3n l\u00e0 3% v\u00e0 gi\u1ea3m \u0111i\u1ec7n \u00e1p c\u1ee7a m\u1ea1ch nh\u00e1nh l\u00ean \u0111\u1ebfn 2%. M\u1eb7c d\u00f9 \u0111\u00e2y ch\u1ec9 l\u00e0 khuy\u1ebfn ngh\u1ecb, nh\u01b0ng n\u00f3 v\u1eabn \u0111\u01b0\u1ee3c nhi\u1ec1u ti\u00eau chu\u1ea9n thi\u1ebft k\u1ebf v\u00e0 quy \u0111\u1ecbnh x\u00e2y d\u1ef1ng \u00e1p d\u1ee5ng ph\u1ed5 bi\u1ebfn. Gi\u1ea3m \u0111i\u1ec7n \u00e1p c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n hi\u1ec7u qu\u1ea3 b\u1eb1ng c\u00e1ch s\u1eed d\u1ee5ng d\u00e2y d\u1eabn c\u00f3 ti\u1ebft di\u1ec7n l\u1edbn h\u01a1n v\u00e0 t\u00ednh \u0111\u1ebfn d\u00f2ng t\u1ea3i ho\u1ea1t \u0111\u1ed9ng, chi\u1ec1u d\u00e0i d\u00e2y d\u1eabn v\u00e0 \u0111i\u1ec7n \u00e1p cung c\u1ea5p.<\/p>\n<h3>Quy t\u1eafc 83% trong NEC l\u00e0 g\u00ec?<\/h3>\n<p>\u0110i\u1ec1u 310.12(A) c\u1ee7a NEC gi\u1ea3i th\u00edch quy t\u1eafc 83%, theo \u0111\u00f3 \u0111\u1ed1i v\u1edbi nh\u00e0 \u1edf m\u1ed9t gia \u0111\u00ecnh, d\u00e2y d\u1eabn c\u1eeda v\u00e0o d\u1ecbch v\u1ee5 c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c ch\u1ecdn k\u00edch th\u01b0\u1edbc b\u1eb1ng 83% c\u1ee7a c\u00f4ng su\u1ea5t d\u1ecbch v\u1ee5 th\u1ef1c t\u1ebf ho\u1eb7c t\u1ea3i. \u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 d\u1ecbch v\u1ee5 d\u00e2n d\u1ee5ng c\u00f3 c\u00f4ng su\u1ea5t \u0111\u1ecbnh m\u1ee9c 200 ampe c\u00f3 th\u1ec3 s\u1eed d\u1ee5ng d\u00e2y d\u1eabn 2\/0 AWG thay v\u00ec d\u00e2y d\u1eabn \u0111\u1ed3ng 3\/0 AWG l\u1edbn h\u01a1n \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u trong \u1ee9ng d\u1ee5ng th\u01b0\u01a1ng m\u1ea1i. Tuy nhi\u00ean, quy t\u1eafc 83% ch\u1ec9 \u00e1p d\u1ee5ng cho d\u00e2y d\u1eabn c\u1eeda v\u00e0o d\u1ecbch v\u1ee5 c\u1ee7a nh\u00e0 \u1edf m\u1ed9t gia \u0111\u00ecnh, trong khi t\u1ea5t c\u1ea3 c\u00e1c d\u00e2y d\u1eabn kh\u00e1c ph\u1ea3i \u0111\u01b0\u1ee3c ch\u1ecdn k\u00edch th\u01b0\u1edbc theo ampacity th\u1ef1c t\u1ebf c\u1ee7a ch\u00fang, \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi c\u00e1c ph\u00e9p t\u00ednh t\u1ea3i v\u00e0 \u0111\u1ecbnh m\u1ee9c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 qu\u00e1 d\u00f2ng cho c\u00e1c m\u1ea1ch \u0111\u00f3.<\/p>\n<h2>T\u00e0i li\u1ec7u tham kh\u1ea3o<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.nfpa.org\" rel=\"nofollow noopener\" target=\"_blank\">NFPA 70 \u2014 B\u1ed9 Quy t\u1eafc \u0110i\u1ec7n Qu\u1ed1c gia (NEC)<\/a>. Ti\u00eau chu\u1ea9n n\u1ec1n t\u1ea3ng cho vi\u1ec7c l\u1eafp \u0111\u1eb7t \u0111i\u1ec7n t\u1ea1i Hoa K\u1ef3, bao g\u1ed3m c\u00e1c \u0110i\u1ec1u 210, 240, 310, v\u00e0 c\u00e1c b\u1ea3ng ampacity v\u00e0 gi\u1ea3m \u0111i\u1ec7n \u00e1p \u0111i\u1ec1u ch\u1ec9nh k\u00edch th\u01b0\u1edbc v\u00e0 l\u1eafp \u0111\u1eb7t d\u00e2y d\u1eabn. Hi\u1ec7p h\u1ed9i Ph\u00f2ng ch\u00e1y Ch\u1eefa ch\u00e1y Qu\u1ed1c gia.<\/li>\n<li><a href=\"https:\/\/www.ul.com\" rel=\"nofollow noopener\" target=\"_blank\">UL \u2014 Ti\u00eau chu\u1ea9n v\u00e0 Ch\u1ee9ng nh\u1eadn D\u00e2y v\u00e0 C\u00e1p<\/a>. C\u00e1c ti\u00eau chu\u1ea9n ki\u1ec3m tra v\u00e0 li\u1ec7t k\u00ea x\u00e1c \u0111\u1ecbnh c\u00e1c m\u1ee9c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n, m\u1ee9c nhi\u1ec7t \u0111\u1ed9 v\u00e0 ampacity c\u1ee7a d\u00e2y v\u00e0 c\u00e1p x\u00e2y d\u1ef1ng.<\/li>\n<li><a href=\"https:\/\/www.ecmag.com\" rel=\"nofollow noopener\" target=\"_blank\">T\u1ea1p ch\u00ed Nh\u00e0 th\u1ea7u \u0110i\u1ec7n \u2014 H\u01b0\u1edbng d\u1eabn \u1ee8ng d\u1ee5ng NEC v\u00e0 T\u00ednh to\u00e1n S\u1ee5t \u00e1p<\/a>. \u1ea4n ph\u1ea9m ng\u00e0nh cung c\u1ea5p h\u01b0\u1edbng d\u1eabn th\u1ef1c ti\u1ec5n v\u1ec1 vi\u1ec7c \u00e1p d\u1ee5ng c\u00e1c quy t\u1eafc k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn, ampacity v\u00e0 s\u1ee5t \u00e1p c\u1ee7a NEC trong c\u00e1c l\u1eafp \u0111\u1eb7t th\u1ef1c t\u1ebf.<\/li>\n<li><a href=\"https:\/\/www.mikeholt.com\" rel=\"nofollow noopener\" target=\"_blank\">Mike Holt Enterprises \u2014 \u0110\u00e0o t\u1ea1o NEC v\u00e0 K\u00edch th\u01b0\u1edbc D\u00e2y d\u1eabn<\/a>. T\u00e0i nguy\u00ean gi\u00e1o d\u1ee5c v\u1ec1 c\u00e1c quy t\u1eafc k\u00edch th\u01b0\u1edbc d\u00e2y d\u1eabn c\u1ee7a NEC, bao g\u1ed3m c\u00e1c c\u00f4ng c\u1ee5 t\u00ednh to\u00e1n t\u01b0\u01a1ng t\u00e1c v\u00e0 c\u00e1c gi\u1ea3i th\u00edch chi ti\u1ebft v\u1ec1 quy t\u1eafc 125%, quy t\u1eafc 83%, v\u00e0 c\u00e1c khuy\u1ebfn ngh\u1ecb v\u1ec1 s\u1ee5t \u00e1p.<\/li>\n<\/ul>\n<p>The \u2192 C\u00e1i <strong>Y\u00eau c\u1ea7u c\u1ee7a NEC \u0111\u1ed1i v\u1edbi d\u00e2y d\u1eabn v\u00e0 \u0111i\u1ec7n \u00e1p m\u00e0 ch\u00fang mang<\/strong> kh\u00f4ng ph\u1ea3i l\u00e0 m\u1ed9t b\u1ea3ng duy nh\u1ea5t hay m\u1ed9t quy t\u1eafc duy nh\u1ea5t. Ch\u00fang l\u00e0 m\u1ed9t m\u1ea1ng l\u01b0\u1edbi c\u00e1c y\u00eau c\u1ea7u li\u00ean quan \u2014 m\u1ee9c \u0111i\u1ec7n \u00e1p c\u00e1ch \u0111i\u1ec7n, ampacity, s\u1ee5t \u00e1p, k\u00edch th\u01b0\u1edbc t\u1ea3i li\u00ean t\u1ee5c, v\u00e0 k\u00edch th\u01b0\u1edbc \u0111\u1ea7u v\u00e0o d\u1ecbch v\u1ee5 \u2014 c\u00f9ng nhau \u0111\u1ea3m b\u1ea3o r\u1eb1ng m\u1ed7i d\u00e2y d\u1eabn trong m\u1ed9t l\u1eafp \u0111\u1eb7t \u0111i\u1ec7n \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh ch\u00ednh x\u00e1c cho \u0111i\u1ec7n \u00e1p, d\u00f2ng \u0111i\u1ec7n, kho\u1ea3ng c\u00e1ch v\u00e0 m\u00f4i tr\u01b0\u1eddng c\u1ee7a n\u00f3. Th\u1ee3 \u0111i\u1ec7n k\u00e9o d\u00e2y d\u1eabn c\u1ee1 12 cho m\u1ea1ch 20 amp, k\u1ef9 s\u01b0 x\u00e1c \u0111\u1ecbnh k\u00edch th\u01b0\u1edbc feeder 500 kcmil cho b\u1ea3ng \u0111i\u1ec1u khi\u1ec3n 400 amp, v\u00e0 thanh tra ki\u1ec3m tra r\u1eb1ng c\u00e1c d\u00e2y d\u1eabn trong \u1ed1ng d\u1eabn \u0111i\u1ec7n h\u1ed7n h\u1ee3p \u0111i\u1ec7n \u00e1p \u0111\u1ec1u \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 cho \u0111i\u1ec7n \u00e1p cao nh\u1ea5t hi\u1ec7n di\u1ec7n \u0111\u1ec1u \u0111ang \u00e1p d\u1ee5ng c\u00f9ng m\u1ed9t khung NEC. Hi\u1ec3u \u0111\u01b0\u1ee3c khung n\u00e0y \u2014 v\u00e0 \u00e1p d\u1ee5ng m\u1ecdi ph\u1ea7n c\u1ee7a n\u00f3, kh\u00f4ng ch\u1ec9 b\u1ea3ng ampacity \u2014 l\u00e0 n\u1ec1n t\u1ea3ng c\u1ee7a vi\u1ec7c l\u1eafp \u0111\u1eb7t \u0111i\u1ec7n an to\u00e0n, tu\u00e2n th\u1ee7 m\u00e3.<\/p>","protected":false},"excerpt":{"rendered":"<p>A recent incident involved a contractor in Illinois who ran cables for a new commercial kitchen by using 10-gauge copper THHN for a 30-amp, three-phase, 208-volt circuit for a convection oven. This type of conductor is rated for 600 volts. The NEC ampacity chart approved 35 amps for use with this conductor in the specific [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3313,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gspb_post_css":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-3312","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blogs"],"blocksy_meta":[],"_links":{"self":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/3312","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/comments?post=3312"}],"version-history":[{"count":1,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/3312\/revisions"}],"predecessor-version":[{"id":3318,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/3312\/revisions\/3318"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media\/3313"}],"wp:attachment":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media?parent=3312"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/categories?post=3312"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/tags?post=3312"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}