{"id":4037,"date":"2026-08-28T09:30:19","date_gmt":"2026-08-28T09:30:19","guid":{"rendered":"https:\/\/huyuglobal.com\/?p=4037"},"modified":"2026-08-28T09:30:21","modified_gmt":"2026-08-28T09:30:21","slug":"12-gauge-wire","status":"publish","type":"post","link":"https:\/\/huyuglobal.com\/vi\/blog\/12-gauge-wire\/","title":{"rendered":"D\u00e2y 12 Gauge: H\u01b0\u1edbng D\u1eabn Ho\u00e0n Ch\u1ec9nh v\u1ec1 Th\u00f4ng S\u1ed1 K\u1ef9 Thu\u1eadt, D\u00f2ng \u0110i\u1ec7n, \u1ee8ng D\u1ee5ng v\u00e0 Chi Ph\u00ed"},"content":{"rendered":"<p>N\u1ebfu b\u1ea1n h\u1ecfi b\u1ea5t k\u1ef3 th\u1ee3 \u0111i\u1ec7n n\u00e0o d\u00e2y d\u1eabn \u0111a n\u0103ng nh\u1ea5t trong m\u1ed9t l\u1eafp \u0111\u1eb7t d\u00e2n d\u1ee5ng ho\u1eb7c th\u01b0\u01a1ng m\u1ea1i nh\u1eb9 l\u00e0 g\u00ec, c\u00e2u tr\u1ea3 l\u1eddi h\u1ea7u nh\u01b0 lu\u00f4n gi\u1ed1ng nhau: 12 AWG (c\u1ee1 12). Th\u1eadt v\u1eady, \u0111\u00e2y l\u00e0 c\u00e1p nh\u1ecf nh\u1ea5t \u0111\u01b0\u1ee3c ph\u00e9p theo National Electric Code cho c\u00e1c m\u1ea1ch nh\u00e1nh 20 amp; t\u1ee9c l\u00e0 c\u00e1c m\u1ea1ch nh\u00e1nh cung c\u1ea5p ph\u1ea7n l\u1edbn cho b\u1ebfp, ph\u00f2ng t\u1eafm, gara v\u00e0 thi\u1ebft b\u1ecb \u0111i\u1ec7n. Tuy nhi\u00ean, c\u00e1c c\u00e2u h\u1ecfi v\u1ec1 ch\u1ee7 \u0111\u1ec1 n\u00e0y v\u1eabn kh\u00f4ng ng\u1eebng xu\u1ea5t hi\u1ec7n: d\u00e2y #12 c\u00f3 bao nhi\u00eau ampe? N\u00f3 c\u00f3 b\u1eb1ng v\u1edbi d\u00e2y 12 AWG t\u01b0\u01a1ng \u0111\u01b0\u01a1ng kh\u00f4ng? T\u00f4i c\u00f3 th\u1ec3 truy\u1ec1n qua n\u00f3 25 ampe trong m\u1ed9t kho\u1ea3ng th\u1eddi gian kh\u00f4ng? V\u00e0 t\u1ea1i sao d\u00e2y trong c\u1eeda h\u00e0ng l\u1ea1i \u0111\u1eaft h\u01a1n nhi\u1ec1u so v\u1edbi THHN trong kho?<\/p>\n<p>H\u01b0\u1edbng d\u1eabn n\u00e0y tr\u1ea3 l\u1eddi t\u1eebng c\u00e2u h\u1ecfi: k\u00edch th\u01b0\u1edbc v\u1eadt l\u00fd c\u1ee7a 12 AWG l\u00e0 g\u00ec, quy t\u1eafc ampacity theo y\u00eau c\u1ea7u c\u1ee7a Code ra sao, c\u00e1p n\u00e0y ph\u1ea3i d\u00f9ng \u1edf \u0111\u00e2u v\u00e0 kh\u00f4ng \u0111\u01b0\u1ee3c d\u00f9ng \u1edf \u0111\u00e2u, gi\u00e1 m\u1ed7i foot cho t\u1ea5t c\u1ea3 c\u00e1c lo\u1ea1i c\u00e1ch \u0111i\u1ec7n ph\u1ed5 bi\u1ebfn, d\u00e2y n\u00e0y so v\u1edbi d\u00e2y c\u1ee1 14, 10 v\u00e0 8 nh\u01b0 th\u1ebf n\u00e0o v\u00e0 mua \u1edf \u0111\u00e2u.<\/p>\n<blockquote><p>\u0110\u01b0\u1eddng k\u00ednh d\u1eabn c\u1ee7a d\u00e2y \u0111\u1ed3ng 12 AWG l\u00e0 0,0808 inch (2,05 mm), l\u00e0 m\u1ee9c t\u1ed1i thi\u1ec3u theo NEC y\u00eau c\u1ea7u cho m\u1ea1ch 20 ampe (NEC 240.4 (D)). M\u1ee9c ampacity t\u1ed1i \u0111a cho lo\u1ea1i d\u1eabn n\u00e0y l\u00e0 20 ampe \u1edf 60\u00b0C (c\u00e1p NM-B) v\u00e0 25 ampe \u1edf 75\u00b0C (THHN\/THWN trong \u1ed1ng d\u1eabn) theo B\u1ea3ng NEC 310.15 (B) (16). \u0110i\u1ec1u n\u00e0y c\u00f3 ngh\u0129a l\u00e0 d\u00f9 d\u00e2y c\u00f3 kh\u1ea3 n\u0103ng t\u1ed1i \u0111a 25 ampe, gi\u1edbi h\u1ea1n 20 ampe ph\u1ea3i \u0111\u01b0\u1ee3c tu\u00e2n th\u1ee7 v\u00ec b\u1ed9 ng\u1eaft m\u1ea1ch ph\u1ea3i b\u1ea3o v\u1ec7 d\u00e2y. Kh\u00f4ng khuy\u1ebfn ngh\u1ecb s\u1eed d\u1ee5ng 25 ampe tr\u00ean d\u00e2y 12 AWG cho c\u00e1c m\u1ea1ch \u1ee9ng d\u1ee5ng chung.<\/p><\/blockquote>\n<h2>D\u00e2y C\u1ee1 12 L\u00e0 G\u00ec? K\u00edch Th\u01b0\u1edbc v\u00e0 \u0110\u01b0\u1eddng K\u00ednh<\/h2>\n<p>\u201cGauge\u201d li\u00ean quan \u0111\u1ebfn h\u1ec7 th\u1ed1ng d\u00e2y d\u1eabn g\u1ecdi l\u00e0 American Wire Gauge (AWG); trong AWG, s\u1ed1 nh\u1ecf h\u01a1n ch\u1ec9 d\u00e2y d\u00e0y h\u01a1n. D\u00e2y \u0111\u1ed3ng \u0111\u1eb7c c\u1ee1 12 c\u00f3 \u0111\u01b0\u1eddng k\u00ednh 0,0808 inch (kho\u1ea3ng 2,05 mm) v\u1edbi ti\u1ebft di\u1ec7n kho\u1ea3ng 3,31 mm\u00b2 (6530 circular mils). L\u1edbp c\u00e1ch \u0111i\u1ec7n l\u00e0m t\u0103ng \u0111\u01b0\u1eddng k\u00ednh t\u1ed5ng th\u1ec3 c\u1ee7a d\u00e2y l\u00ean kho\u1ea3ng 0,119-0,128 inch, t\u00f9y thu\u1ed9c v\u00e0o lo\u1ea1i c\u00e1ch \u0111i\u1ec7n s\u1eed d\u1ee5ng v\u00e0 d\u00e2y c\u00f3 d\u1eabn \u0111\u1eb7c hay b\u1ec7n.<\/p>\n<p>C\u00f3 hai d\u1ea1ng d\u00e2y; d\u1eabn \u0111\u1eb7c, l\u00e0 m\u1ed9t d\u00e2y c\u1ee9ng d\u00f9ng trong c\u00e1p NM-B (Romex), v\u00e0 d\u00e2y b\u1ec7n, l\u00e0m t\u1eeb 19 s\u1ee3i xo\u1eafn l\u1ea1i v\u1edbi nhau v\u00e0 d\u00f9ng trong d\u00e2y THHN, c\u0169ng nh\u01b0 trong c\u00e1c \u1ee9ng d\u1ee5ng linh ho\u1ea1t. D\u1ea1ng sau linh ho\u1ea1t h\u01a1n v\u00e0 c\u00f3 kh\u1ea3 n\u0103ng ch\u1ecbu u\u1ed1n cao h\u01a1n, l\u00e0m cho d\u00e2y b\u1ec7n ph\u00f9 h\u1ee3p h\u01a1n v\u1edbi c\u00e1c h\u1ec7 th\u1ed1ng \u0111i\u1ec7n kh\u00e1c nhau.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4039\" style=\"text-align: center;\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/How-Many-Amps-Can-12-AWG-Carry.webp\" alt=\"D\u00e2y 12 AWG C\u00f3 Th\u1ec3 Ch\u1ecbu \u0110\u01b0\u1ee3c Bao Nhi\u00eau Ampe? Quy T\u1eafc Code\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>D\u00e2y 12 AWG C\u00f3 Th\u1ec3 Ch\u1ecbu \u0110\u01b0\u1ee3c Bao Nhi\u00eau Ampe? Quy T\u1eafc Code<\/h2>\n<p>C\u00f4ng su\u1ea5t c\u00e1p c\u1ee7a d\u00e2y \u0111\u1ed3ng 12 AWG \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi nhi\u1ec7t \u0111\u1ed9 c\u00e1ch \u0111i\u1ec7n, trong khi th\u00f4ng s\u1ed1 m\u1ea1ch \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi c\u01a1 ch\u1ebf b\u1ea3o v\u1ec7 c\u1ee7a b\u1ed9 ng\u1eaft m\u1ea1ch. C\u00f3 hai lo\u1ea1i gi\u00e1 tr\u1ecb:<\/p>\n<ul>\n<li>C\u00f4ng su\u1ea5t d\u1eabn (c\u00f4ng su\u1ea5t v\u1eadt l\u00fd c\u1ee7a d\u00e2y), nh\u01b0 ch\u1ec9 ra trong B\u1ea3ng NEC 310.15(B)(16), n\u01a1i d\u00e2y c\u00f3 c\u00f4ng su\u1ea5t 25 ampe \u1edf 75\u00b0C (c\u00e1p THHN\/THWN trong \u1ed1ng) v\u00e0 30 ampe \u1edf 90\u00b0C (d\u00e2y THHN v\u1edbi \u0111\u1ea7u n\u1ed1i c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng \u1edf 90\u00b0C).<\/li>\n<li>Dung l\u01b0\u1ee3ng m\u1ea1ch (dung l\u01b0\u1ee3ng c\u1ee7a c\u01a1 ch\u1ebf b\u1ea3o v\u1ec7), nh\u01b0 \u0111\u01b0\u1ee3c quy \u0111\u1ecbnh trong NEC 240.4(D), trong \u0111\u00f3 c\u1ea7u dao ph\u1ea3i cung c\u1ea5p b\u1ea3o v\u1ec7 cho d\u00e2y \u0111\u1ed3ng 12 AWG v\u1edbi m\u1ee9c kh\u00f4ng v\u01b0\u1ee3t qu\u00e1 20 ampe.<\/li>\n<\/ul>\n<p>Vi\u1ec7c s\u1eed d\u1ee5ng c\u00f3 ngh\u0129a l\u00e0 m\u1ed9t m\u1ea1ch 12 AWG c\u00f3 c\u1ea7u dao \u0111\u1ecbnh m\u1ee9c 20 Ampe, trong khi d\u00e2y c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng d\u01b0\u1edbi t\u1ea3i li\u00ean t\u1ee5c 16 Ampe (quy t\u1eafc 80%). \u0110\u1ecbnh m\u1ee9c 25 Ampe \u1edf 75\u00b0C t\u1ed3n t\u1ea1i \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o bi\u00ean an to\u00e0n v\u00e0 cho m\u1ed9t s\u1ed1 ngo\u1ea1i l\u1ec7 trong m\u00e3, kh\u00f4ng ph\u1ea3i \u0111\u1ec3 k\u1ebft n\u1ed1i c\u1ea7u dao 25A v\u1edbi d\u00e2y 12 AWG. N\u1ebfu c\u00f3 b\u1ea5t k\u1ef3 nghi ng\u1edd n\u00e0o v\u1ec1 d\u00e2y s\u1eed d\u1ee5ng, s\u1ebd \u0111\u01b0\u1ee3c khuy\u00ean theo m\u1ea1ch \u0111\u1ecbnh m\u1ee9c th\u1ea5p h\u01a1n \u0111\u1ec3 \u0111\u1ea3m b\u1ea3o an to\u00e0n cho d\u00e2y.<\/p>\n<h2>C\u00e1c lo\u1ea1i 12 AWG: THHN, NM-B, UF-B, MC \u2014 S\u1ef1 kh\u00e1c bi\u1ec7t l\u00e0 g\u00ec<\/h2>\n<p>C\u00e1c ki\u1ec3u c\u00e1ch c\u00e1ch \u0111i\u1ec7n\/c\u1ea5u tr\u00fac kh\u00e1c nhau t\u1ed3n t\u1ea1i cho 12 AWG, m\u1ed7i lo\u1ea1i c\u00f3 m\u00e3 l\u1eafp \u0111\u1eb7t ri\u00eang.<\/p>\n<table>\n<thead>\n<tr>\n<th>Lo\u1ea1i<\/th>\n<th>C\u1ea5u tr\u00fac<\/th>\n<th>Dung l\u01b0\u1ee3ng d\u00f2ng \u0111i\u1ec7n (12 AWG Cu)<\/th>\n<th>N\u01a1i s\u1eed d\u1ee5ng<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>THHN\/THWN-2<\/td>\n<td>D\u00e2y d\u1eabn \u0111\u01a1n, c\u00e1ch \u0111i\u1ec7n PVC + \u00e1o nylon<\/td>\n<td>25A (75\u00b0C); 30A (90\u00b0C)<\/td>\n<td>\u1ed0ng d\u1eabn v\u00e0 khay c\u00e1p trong th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p; 600V; v\u1ecb tr\u00ed \u1ea9m \u01b0\u1edbt ho\u1eb7c kh\u00f4<\/td>\n<\/tr>\n<tr>\n<td>NM-B (Romex)<\/td>\n<td>2-4 d\u00e2y d\u1eabn trong v\u1ecf PVC, d\u00e2y \u0111\u1eb7c ho\u1eb7c b\u1ec7n<\/td>\n<td>20A (60\u00b0C)<\/td>\n<td>Nh\u00e0 \u1edf v\u00e0 th\u01b0\u01a1ng m\u1ea1i nh\u1eb9, gi\u1ea5u trong t\u01b0\u1eddng\/tr\u1ea7n<\/td>\n<\/tr>\n<tr>\n<td>UF-B<\/td>\n<td>Ki\u1ec3u NM v\u1edbi \u00e1o ch\u1ed1ng \u1ea9m<\/td>\n<td>20A (60\u00b0C)<\/td>\n<td>D\u00e2y c\u1ea5p ng\u1ea7m \u0111\u1ebfn nh\u00e0 kho\/ga-ra v\u00e0 ch\u1ea1y ngo\u00e0i tr\u1eddi<\/td>\n<\/tr>\n<tr>\n<td>C\u00e1p MC<\/td>\n<td>D\u00e2y d\u1eabn b\u00ean trong l\u1edbp gi\u00e1p kim lo\u1ea1i linh ho\u1ea1t<\/td>\n<td>20A (\u0111\u1ecbnh m\u1ee9c 75\u00b0C \u0111i\u1ec3n h\u00ecnh)<\/td>\n<td>Th\u01b0\u01a1ng m\u1ea1i, ch\u1ea1y l\u1ed9, khu v\u1ef1c ch\u1ed1ng ch\u00e1y<\/td>\n<\/tr>\n<tr>\n<td>THW\/THWN \u0111\u01a1n<\/td>\n<td>T\u01b0\u01a1ng t\u1ef1 d\u00f2ng THHN<\/td>\n<td>25A (75\u00b0C)<\/td>\n<td>V\u1ecb tr\u00ed \u1ea9m \u01b0\u1edbt, d\u00e2y c\u1ea5p c\u00f4ng nghi\u1ec7p<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>M\u1ed9t trong nh\u1eefng l\u1ef1a ch\u1ecdn t\u1ed1t cho ch\u1ea1y \u1ed1ng d\u1eabn l\u00e0 THHN\/THWN-2, c\u00f3 chi ph\u00ed th\u1ea5p h\u01a1n m\u1ed7i foot so v\u1edbi d\u00e2y NM-B v\u00ec ch\u1ec9 s\u1eed d\u1ee5ng m\u1ed9t d\u00e2y d\u1eabn trong d\u00e2y n\u00e0y, trong khi NM-B (th\u01b0\u01a1ng hi\u1ec7u Romex thu\u1ed9c s\u1edf h\u1eefu c\u1ee7a Southwire) l\u00e0 d\u00e2y ti\u00eau chu\u1ea9n d\u00f9ng trong l\u1eafp \u0111\u1eb7t th\u00f4 nh\u00e0 \u1edf. UF-B \u0111\u01b0\u1ee3c d\u00f9ng cho l\u1eafp \u0111\u1eb7t d\u00e2y ng\u1ea7m, v\u00e0 MC l\u00e0 t\u00ean g\u1ecdi c\u1ee7a d\u00e2y gi\u00e1p d\u00f9ng trong l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i.<\/p>\n<h2>N\u01a1i s\u1eed d\u1ee5ng d\u00e2y 12 Gauge (v\u00e0 n\u01a1i kh\u00f4ng s\u1eed d\u1ee5ng)<\/h2>\n<p>Theo \u0110i\u1ec1u 210 c\u1ee7a m\u00e3 NEC, c\u00e1c m\u1ea1ch cho thi\u1ebft b\u1ecb nh\u1ecf trong b\u1ebfp, khu v\u1ef1c \u0103n u\u1ed1ng v\u00e0 gi\u1eb7t l\u00e0 n\u00ean l\u00e0 20 ampe (210.52), \u0111\u1ed3ng th\u1eddi c\u00e1c m\u1ea1ch cho ph\u00f2ng t\u1eafm c\u0169ng n\u00ean l\u00e0 20 ampe (210.11(C)(3)). T\u1ea5t c\u1ea3 c\u00e1c m\u1ea1ch n\u00e0y n\u00ean \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t v\u1edbi d\u00e2y 12 AWG. C\u00e1c \u1ee9ng d\u1ee5ng ti\u00eau chu\u1ea9n kh\u00e1c:<\/p>\n<ul>\n<li>\u1ed4 c\u1eafm khu v\u1ef1c b\u1ebfp v\u00e0 \u0103n u\u1ed1ng \u2013 m\u1ea1ch cho thi\u1ebft b\u1ecb nh\u1ecf 20 ampe \u0111\u01b0\u1ee3c y\u00eau c\u1ea7u theo m\u00e3;<\/li>\n<li>M\u1ea1ch \u1ed5 c\u1eafm ph\u00f2ng t\u1eafm \u2013 20 ampe v\u00e0 \u0111\u01b0\u1ee3c trang b\u1ecb GFCI;<\/li>\n<li>\u1ed4 c\u1eafm ga-ra v\u00e0 x\u01b0\u1edfng \u2013 20 ampe cho d\u1ee5ng c\u1ee5 bao g\u1ed3m m\u00e1y c\u01b0a b\u00e0n v\u00e0 m\u00e1y h\u00fat b\u1ee5i;<\/li>\n<li>M\u00e1y \u0111i\u1ec1u h\u00f2a kh\u00f4ng kh\u00ed c\u1eeda s\u1ed5 \u2013 15 ampe ch\u1ea1y tr\u00ean m\u1ea1ch 20 ampe v\u1edbi d\u00e2y 12 AWG;<\/li>\n<li>\u1ed4 c\u1eafm v\u00e0 chi\u1ebfu s\u00e1ng \u0111a n\u0103ng trong c\u00f4ng tr\u00ecnh x\u00e2y d\u1ef1ng m\u1edbi \u2013 nhi\u1ec1u th\u1ee3 \u0111i\u1ec7n s\u1eed d\u1ee5ng d\u00e2y 12 AWG to\u00e0n b\u1ed9 c\u00f4ng tr\u00ecnh c\u00f3 ho\u1eb7c kh\u00f4ng tr\u1ed9n v\u1edbi d\u00e2y 14.<\/li>\n<li>D\u00e2y c\u1ea5p \u0111\u1ebfn b\u1ea3ng ph\u1ee5 v\u00e0 c\u00f4ng tr\u00ecnh \u2013 th\u01b0\u1eddng, c\u00e1c d\u00e2y c\u1ea5p ng\u1eafn trong dung l\u01b0\u1ee3ng cho ph\u00e9p; c\u00e1c d\u00e2y c\u1ea5p d\u00e0i n\u00ean d\u00f9ng d\u00e2y 10 AWG ho\u1eb7c d\u00e0y h\u01a1n.<\/li>\n<\/ul>\n<p>N\u01a1i 12 AWG kh\u00f4ng ph\u00f9 h\u1ee3p: M\u1ea1ch chi\u1ebfu s\u00e1ng 15A c\u00f3 th\u1ec3 ho\u1ea1t \u0111\u1ed9ng t\u1ed1t v\u1edbi d\u00e2y 14 AWG; thi\u1ebft b\u1ecb 240V tr\u00ean 20A n\u00ean \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i s\u1eed d\u1ee5ng d\u00e2y \u00edt nh\u1ea5t 10 AWG; c\u00e1c \u0111o\u1ea1n feeder d\u00e0i n\u00ean s\u1eed d\u1ee5ng c\u00e1p k\u00edch th\u01b0\u1edbc l\u1edbn h\u01a1n do s\u1ee5t \u00e1p. N\u1ebfu b\u1ea1n \u0111ang \u0111i d\u00e2y cho subpanel ho\u1eb7c thi\u1ebft b\u1ecb n\u1eb7ng, h\u01b0\u1edbng d\u1eabn c\u1ee7a ch\u00fang t\u00f4i v\u1ec1 <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/how-many-watts-on-a-15-amp-circuit\/\">m\u1ea1ch 15 amp th\u1ef1c s\u1ef1 c\u00f3 th\u1ec3 mang t\u1ea3i bao nhi\u00eau<\/a> v\u00e0 <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/what-is-mccb-and-mcb\/\">Ph\u00e2n t\u00edch MCB v\u00e0 MCCB<\/a> gi\u00fap b\u1ea1n ch\u1ecdn d\u00e2y ph\u00f9 h\u1ee3p v\u1edbi b\u1ed9 ng\u1eaft m\u1ea1ch v\u00e0 t\u1ea3i \u0111\u00fang c\u00e1ch.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4040\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/12-AWG-vs-14-10-and-8-Gauge-How-to-Choose.webp\" alt=\"So s\u00e1nh 12 AWG v\u1edbi 14, 10 v\u00e0 8 Gauge: C\u00e1ch ch\u1ecdn\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>So s\u00e1nh 12 AWG v\u1edbi 14, 10 v\u00e0 8 Gauge: C\u00e1ch ch\u1ecdn<\/h2>\n<table>\n<thead>\n<tr>\n<th>AWG (\u0111\u1ed3ng)<\/th>\n<th>\u0110\u01b0\u1eddng k\u00ednh<\/th>\n<th>Max Circuit (NEC 240.4(D))<\/th>\n<th>Ampacity 75\u00b0C<\/th>\n<th>S\u1eed d\u1ee5ng \u0111i\u1ec3n h\u00ecnh<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>14 AWG<\/td>\n<td>0.0641&#8243; (1.63 mm)<\/td>\n<td>15A<\/td>\n<td>20A<\/td>\n<td>Lighting, 15A general circuits<\/td>\n<\/tr>\n<tr>\n<td>12 AWG<\/td>\n<td>0.0808&#8243; (2.05 mm)<\/td>\n<td>20A<\/td>\n<td>25A<\/td>\n<td>Kitchen\/bath\/garage receptacles, tools<\/td>\n<\/tr>\n<tr>\n<td>10 AWG<\/td>\n<td>0.1019&#8243; (2.59 mm)<\/td>\n<td>30A<\/td>\n<td>35A<\/td>\n<td>Water heaters, AC units, EV chargers<\/td>\n<\/tr>\n<tr>\n<td>8 AWG<\/td>\n<td>0.1285&#8243; (3.26 mm)<\/td>\n<td>40A<\/td>\n<td>50A<\/td>\n<td>Dryers, subpanel feeders<\/td>\n<\/tr>\n<tr>\n<td>6 AWG<\/td>\n<td>0.162&#8243; (4.11 mm)<\/td>\n<td>55A<\/td>\n<td>65A<\/td>\n<td>Range, heavy feeders<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The basic rule of thumb is that the wires should match the circuit breaker, and the circuit breaker should match the load. Whenever the circuit is designed for a potential load of 20A (for example, in kitchens, bathrooms, garages and workshops) it makes sense to use 12 AWG cable. For circuits that are strictly 15A lighting circuits, using 14 AWG copper cable is advisable because it will save you money as well as being compliant with the local electrical codes. For loads that operate at 240V and demand from 25-30A, it is better to switch to 10 AWG. A lot of electricians make an effort not to switch wire sizes throughout the job and often use 12 AWG wire even when it is not required by the regulations since the additional cost is minimal and there is no need to fear that you will use the wrong wire.<\/p>\n<h2>Voltage Drop and Run Length<\/h2>\n<p>Voltage drop is one of the costs that go unnoticed in long wires. For a circuit carrying 20A for 50 feet, 12 AWG copper wire will show a voltage drop of about 2.8V (2.3%), which is acceptable under the National Electrical Code (NEC) recommendations of 3% for branch circuits. However, 14 AWG copper wire in a similar run will drop 4.5V (3.75%), which is above the limit. Extended wiring lowers the starting torque of motors, dims lights and can cause other problems. In practice, if we need to run 20A for distances longer than 75-100 feet, it is recommended to either switch to 10 AWG wire or use two circuits. If the wire should be longer than 100 feet, the calculation of voltage drop according to NEC Chapter 9, table 8 is necessary.<\/p>\n<h2>Copper vs Aluminum<\/h2>\n<p>Because copper is nearly as good a conductor as the theoretical 100% efficacy (95%), but because of its many advantages, copper is the preferred metal to be used in branch circuits. Although aluminum is almost one-third lighter, the codes specify that aluminum wires must be two gauges larger than copper wires and that special connections must be used with this material. Therefore, 12-gauge wires are never going to be aluminum wires; however, the latter would be used to minimize costs in main service feeder cables.<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-4041\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/How-Much-Does-12-Gauge-Wire-Cost.webp\" alt=\"How Much Does 12 Gauge Wire Cost\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>How Much Does 12 Gauge Wire Cost?<\/h2>\n<p>Copper market rates vary, but the prices for 12 AWG copper in the USA remain constant.<\/p>\n<table>\n<thead>\n<tr>\n<th>S\u1ea3n ph\u1ea9m<\/th>\n<th>Gi\u00e1 \u0111i\u1ec3n h\u00ecnh<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>THHN 12 AWG single conductor (loose)<\/td>\n<td>$0.39-0.56 per foot (bulk 1000-ft pricing at the low end)<\/td>\n<\/tr>\n<tr>\n<td>12\/2 NM-B cable (Romex-type, with ground)<\/td>\n<td>$0.50-0.80 per foot<\/td>\n<\/tr>\n<tr>\n<td>12\/3 NM-B cable (for 3-way circuits, with ground)<\/td>\n<td>$0.70-1.10 per foot<\/td>\n<\/tr>\n<tr>\n<td>12 AWG NM-B, 100-foot spool<\/td>\n<td>$20-35<\/td>\n<\/tr>\n<tr>\n<td>12 AWG NM-B, 250-500 ft spool (bulk)<\/td>\n<td>$50-170 depending on brand and copper price<\/td>\n<\/tr>\n<tr>\n<td>10 AWG 12\/2 NM-B equivalent (for comparison)<\/td>\n<td>about $1.20 per foot<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Purchasing in bulk is an excellent way to save money: 500-foot wire spools of 12\/2 NM-B from a wholesaler have prices that are up to 30% lower than those charged for buying bulky 50-foot cuts from a retail outlet. Many online wholesalers (like Wire &amp; Cable Your Way and WesBell) post online wire prices that are much lower than those of conventional large retailers for similar UL-registered wire.<\/p>\n<h2>Recommended Brands and Manufacturers<\/h2>\n<p>UL-listed wire is treated as a product of a commodity nature due to the fact that what matters more is the insulation and copper used for the wire, and all the leading brands offer compliance with UL 83\/1063. But there are some brands which have stood firm in the wire making industry:<\/p>\n<ul>\n<li>Southwire \u2014 the biggest wire company in the USA. Its Romex wire brand has become a standard in NM-B wire. It is sold in all leading chain stores and wire distributors.<\/li>\n<li>Cerro Wire \u2014 a well-known company in the USA. It has the prices which are 10-15% higher than other brands, but it offers high-quality insulation.<\/li>\n<li>Wire &amp; Cable Your Way \u2014 a distributor who sells Southwire wire and many similar wires at low prices.<\/li>\n<li>WesBell Electronics \u2014 the company specializes in direct sales and offers THHN wire at per-foot basis.<\/li>\n<li>General Cable\/Prysmian \u2014 an industrial-grade wire THHN and tray cable make.<\/li>\n<\/ul>\n<p>When purchasing wires be sure to check the UL chairman, and the print on wire (12-2 w\/Grd NM-B 600V), the manufacture date code from NM-B spools, and make sure the wire is correctly marked. The price difference between budget wires and premium ones is just several dollars.For the breaker that protects that wire, pairing it with a certified <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/what-is-ul-489-breakers\/\">UL 489 breaker<\/a> and understanding <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/how-to-tell-if-a-breaker-is-bad\/\">how to spot a failing breaker<\/a> closes the loop on a safe circuit, and in wet locations the <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/gfci-stands-for-ground-fault-circuit-interrupter\/\">H\u01b0\u1edbng d\u1eabn b\u1ea3o v\u1ec7 GFCI<\/a> explains the additional layer 12 AWG circuits need in kitchens and baths.<\/p>\n<h2>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n<h3>How many amps will #12 wire carry?<\/h3>\n<p>According to NEC Table 310.15(B)(16), 12 AWG copper can carry current of 25A at 75 degrees Celsius (THHN\/THWN in conduit) and 30A at 90 degrees Celsius. However, it is stated in NEC 240.4(D) that for most applications it must be secured at not more than 20A because NM-B cables and standard terminations are rated for 60 degrees Celsius. The practical result for circuit design is the following: 12 AWG means 20-amp circuit.<\/p>\n<h3>How thick is 12 gauge electrical wire?<\/h3>\n<p>The diameter of bare copper wire of 12 AWG is .0808 inches (2.05 mm). The diameter of wire with THHN insulation is roughly .128 inches (3.25 mm) and the complete NM-B wire assembly is roughly 0.4 x 0.2 inches. It is clearly thicker than 14 AWG (.0641&#8243;) and noticeably thinner than 10 AWG (.1019&#8243;).<\/p>\n<h3>Is 12 gauge and 12 AWG the same thing?<\/h3>\n<p>Yes, AWG means American Wire Gauge and there is no difference between 12 AWG and 12 gauge. It is a system of wire size identification that is used in North America. Both terms are used to describe copper wire with 0.0808 inches in diameter and a 20A circuit capacity (It should be mentioned that in some countries the cross-sectional area of wire is measured in mm2 \u2013 12 AWG is approximately 3.3-4 mm2.).<\/p>\n<h3>Can you run 25 amps on 12 gauge wire?<\/h3>\n<p>No, it is impossible for normal branch circuits. Although 12 AWG THHN is rated for 25 amps at 75 degrees Celsius, NEC 240.4(D) sets the limit for that wire to 20A for copper wires and 20A for 12 AWG wires with insulation rating of 60 degrees Celsius in most cases.<\/p>\n<h2>T\u00e0i li\u1ec7u tham kh\u1ea3o<\/h2>\n<ul>\n<li><a href=\"https:\/\/wesbellwireandcable.com\/products\/electrical-wire\/thhn-wire\/copper-thhn-electrical-wire-12-str\/\" rel=\"nofollow noopener\" target=\"_blank\">WesBell Electronics \u2014 THHN 12 AWG stranded copper: specs and pricing<\/a><\/li>\n<li><a href=\"https:\/\/www.lapptannehill.com\/thhn-building-wire-12-awg-brown-stranded-conductor\" rel=\"nofollow noopener\" target=\"_blank\">Lapp Tannehill \u2014 12 AWG THHN building wire technical data<\/a><\/li>\n<li><a href=\"https:\/\/toolsradar.com\/12-gauge-wire-for-20-amp-can-it-handle-your-woodshops-needs\/\" rel=\"nofollow noopener\" target=\"_blank\">ToolsRadar \u2014 12 gauge wire for 20-amp circuits: ampacity and cost analysis<\/a><\/li>\n<li><a href=\"https:\/\/th.qlcables.com\/message?product_id=1576\" rel=\"nofollow noopener\" target=\"_blank\">QL Cables \u2014 NM-B 14-6 AWG pricing and NEC compliance overview<\/a><\/li>\n<li><a href=\"https:\/\/www.nfpa.org\/codes-and-standards\/nfpa-70\" rel=\"nofollow noopener\" target=\"_blank\">NFPA 70 \u2014 National Electrical Code (NEC 240.4, Table 310.15(B)(16), Article 210)<\/a><\/li>\n<\/ul>\n<h2>K\u1ebft lu\u1eadn<\/h2>\n<p>The 12 AWG wire is well known for being the best performing wire when it comes to electrical conduction, being suitable for assisting various electrical appliances such as tools, cooking devices and much more. Its operation is based on the following principles \u2014 the wire has a maximum capacity of carrying 25 amps at 75 degrees Celsius, but the regular breaker has 20 amps. When it comes to purchasing the wire, certain aspects such as type of insulation (NM-B in the case of residential homes, THHN in case of conduit wiring), length of the wire and its material (copper should be preferred over aluminum) become of paramount significance. Finally, with the price fluctuating somewhere between $0.40 and $0.80 per foot, the use of 12 AWG in one\u2019s project is a trivial task when it comes to budgeting.<\/p>","protected":false},"excerpt":{"rendered":"<p>If you ask any electrician what the most versatile wire is in a residential or light commercial installation, the answer will almost always be the same: 12 AWG (12 gauge). Indeed, it is the smallest cable permitted by the National Electric Code for 20-amp branch circuits; this is, the branch circuits supplying most of the [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":4042,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gspb_post_css":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-4037","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\/4037","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=4037"}],"version-history":[{"count":3,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/4037\/revisions"}],"predecessor-version":[{"id":4044,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/4037\/revisions\/4044"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media\/4042"}],"wp:attachment":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media?parent=4037"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/categories?post=4037"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/tags?post=4037"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}