{"id":3700,"date":"2026-08-14T19:25:51","date_gmt":"2026-08-14T19:25:51","guid":{"rendered":"https:\/\/huyuglobal.com\/?p=3700"},"modified":"2026-08-14T19:25:51","modified_gmt":"2026-08-14T19:25:51","slug":"maximum-resistance-recommended-for-commercial-building-electrical-installation","status":"publish","type":"post","link":"https:\/\/huyuglobal.com\/vi\/blog\/maximum-resistance-recommended-for-commercial-building-electrical-installation\/","title":{"rendered":"Gi\u00e1 Tr\u1ecb Tr\u1edf Kh\u00e1ng T\u1ed1i \u0110a \u0110\u01b0\u1ee3c Khuy\u1ebfn Ngh\u1ecb cho L\u1eafp \u0110\u1eb7t \u0110i\u1ec7n T\u00f2a Nh\u00e0 Th\u01b0\u01a1ng M\u1ea1i"},"content":{"rendered":"<p>M\u1ed9t ng\u01b0\u1eddi \u0111\u1ebfn \u0111\u1ec3 th\u1ef1c hi\u1ec7n ki\u1ec3m tra \u0111i\u1ec7n trong t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i c\u1ee7a b\u1ea1n. K\u1ef9 s\u01b0 th\u00f4ng b\u00e1o v\u1edbi anh ta r\u1eb1ng \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t \u0111\u00e3 \u0111\u01b0\u1ee3c ki\u1ec3m tra \u1edf m\u1ee9c 22 Ohms. M\u1ed9t ng\u01b0\u1eddi g\u1ea7n \u0111\u00f3 n\u00f3i r\u1eb1ng v\u00ec NEC cho ph\u00e9p 25 Ohms, m\u1ecdi th\u1ee9 \u0111\u1ec1u \u1ed5n. Nh\u01b0ng s\u1ed5 tay c\u1ee7a nh\u00e0 s\u1ea3n xu\u1ea5t thi\u1ebft b\u1ecb ghi r\u1eb1ng c\u1ea7n t\u1ed1i \u0111a 5 Ohm v\u00ec n\u00f3 ho\u1ea1t \u0111\u1ed9ng v\u1edbi \u0111i\u1ec7n t\u1eed nh\u1ea1y c\u1ea3m; do \u0111\u00f3, k\u1ef9 s\u01b0 v\u1eadn h\u00e0nh tr\u00edch d\u1eabn m\u1ed9t th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt m\u1edbi \u0111\u1ed1i v\u1edbi b\u1ea1n. Gi\u00e1 tr\u1ecb n\u00e0o c\u1ea7n \u0111\u01b0\u1ee3c tu\u00e2n theo? C\u00e2u h\u1ecfi n\u00e0y r\u1ea5t ph\u1ed5 bi\u1ebfn \u0111\u1ed1i v\u1edbi nh\u1eefng ng\u01b0\u1eddi l\u00e0m vi\u1ec7c trong l\u0129nh v\u1ef1c \u0111i\u1ec7n th\u01b0\u01a1ng m\u1ea1i, nh\u01b0ng c\u00e2u tr\u1ea3 l\u1eddi ph\u1ee5 thu\u1ed9c v\u00e0o ti\u00eau chu\u1ea9n b\u1ea1n \u0111ang \u0111o l\u01b0\u1eddng.<\/p>\n<p>B\u00e0i vi\u1ebft n\u00e0y s\u1ebd cho b\u1ea1n c\u00e2u tr\u1ea3 l\u1eddi ngay l\u1eadp t\u1ee9c v\u1edbi c\u00e1c con s\u1ed1 ch\u00ednh x\u00e1c \u2013 kh\u00f4ng s\u1eed d\u1ee5ng c\u00e1c con s\u1ed1 t\u01b0\u1edfng t\u01b0\u1ee3ng. B\u1ea1n s\u1ebd bi\u1ebft ch\u00ednh x\u00e1c NEC y\u00eau c\u1ea7u g\u00ec, IEEE n\u00f3i g\u00ec, c\u00e1ch \u201cquy t\u1eafc 25 Ohm ho\u1ea1t \u0111\u1ed9ng,\u201d v\u00e0 \u0111i\u1ec1u g\u00ec \u0111\u01b0\u1ee3c coi l\u00e0 an to\u00e0n.<\/p>\n<blockquote><p>N\u1ebfu b\u1ea1n \u0111ang t\u00ecm c\u00e2u tr\u1ea3 l\u1eddi nhanh, th\u00ec kh\u00f4ng c\u00f3 con s\u1ed1 r\u00f5 r\u00e0ng n\u00e0o \u00e1p d\u1ee5ng chung cho \u0111i\u1ec7n tr\u1edf t\u1ed1i \u0111a c\u1ee7a ti\u1ebfp \u0111\u1ea5t trong t\u1ea5t c\u1ea3 c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i v\u00ec c\u00e2u tr\u1ea3 l\u1eddi n\u00e0y ph\u1ee5 thu\u1ed9c v\u00e0o ti\u00eau chu\u1ea9n n\u00e0o v\u00e0 ph\u1ea7n n\u00e0o c\u1ee7a h\u1ec7 th\u1ed1ng b\u1ea1n \u0111\u1ec1 c\u1eadp. NEC (NFPA 70) kh\u00f4ng c\u00f3 \u0111i\u1ec7n tr\u1edf t\u1ed1i \u0111a chung cho m\u1ed9t t\u00f2a nh\u00e0, m\u00e0 s\u1ef1 k\u1ebft h\u1ee3p 25 ohms (th\u1ef1c ra \u0111\u01b0\u1ee3c quy \u0111\u1ecbnh trong 250.53) mang t\u00ednh th\u1ef1c ti\u1ec5n khi n\u00f3i v\u1ec1 thanh ho\u1eb7c t\u1ea5m ti\u1ebfp \u0111\u1ea5t v\u00e0 ch\u1ec9 \u0111\u01b0\u1ee3c d\u00f9ng \u0111\u1ec3 xem li\u1ec7u 1 thanh ho\u1eb7c t\u1ea5m c\u00f3 \u0111\u1ee7 cho \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t hay kh\u00f4ng (t\u1ee9c l\u00e0, n\u1ebfu 1 \u0111i\u1ec7n c\u1ef1c c\u00f3 \u0111i\u1ec7n tr\u1edf 25 ohms ho\u1eb7c th\u1ea5p h\u01a1n th\u00ec kh\u00f4ng c\u1ea7n d\u00f9ng \u0111i\u1ec7n c\u1ef1c th\u1ee9 hai). \u0110\u1ed1i v\u1edbi c\u00e1c h\u1ec7 th\u1ed1ng th\u01b0\u01a1ng m\u1ea1i v\u00e0 c\u00f4ng nghi\u1ec7p l\u1edbn, IEEE\u2019s Std 142 (\u201cGreen Book\u201d) quy \u0111\u1ecbnh r\u1eb1ng \u0111i\u1ec7n tr\u1edf c\u1ee7a \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t ch\u00ednh v\u1edbi \u0111\u1ea5t ph\u1ea3i n\u1eb1m trong kho\u1ea3ng 1-5 ohms, v\u00e0 th\u1ef1c ti\u1ec5n ng\u00e0nh (khuy\u1ebfn ngh\u1ecb NFPA\/IEEE, th\u1ef1c h\u00e0nh NETA ATS, ti\u00eau chu\u1ea9n ng\u00e0nh vi\u1ec5n th\u00f4ng, v.v.) nh\u1eb1m \u0111\u1ea1t kho\u1ea3ng 5 ohms cho c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i v\u00e0 th\u1eadm ch\u00ed 1 ohm cho c\u00e1c tr\u1ea1m bi\u1ebfn \u00e1p v\u00e0 nh\u00e0 m\u00e1y ph\u00e1t \u0111i\u1ec7n. T\u00f3m l\u1ea1i, y\u00eau c\u1ea7u t\u1ed1i thi\u1ec3u c\u1ee7a NEC kh\u00f4ng li\u00ean quan \u0111\u1ebfn hi\u1ec7u su\u1ea5t y\u00eau c\u1ea7u b\u1edfi IEEE v\u1ec1 ph\u1ea1m vi gi\u00e1 tr\u1ecb 1-5 ohms cho c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i, \u0111i\u1ec1u n\u00e0y \u0111\u00e3 \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn r\u1ed9ng r\u00e3i nh\u01b0 m\u1ed9t gi\u00e1 tr\u1ecb m\u1ee5c ti\u00eau trong ng\u00e0nh trong khi b\u1ea5t k\u1ef3 gi\u00e1 tr\u1ecb n\u00e0o tr\u00ean 25 ohms \u0111\u01b0\u1ee3c xem l\u00e0 k\u00e9m v\u00e0 kh\u00f4ng ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c \u0111\u1ed1i v\u1edbi \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t th\u01b0\u01a1ng m\u1ea1i.<\/p><\/blockquote>\n<p>H\u00e3y ch\u00ednh x\u00e1c, v\u00ec \u0111\u00e2y l\u00e0 n\u01a1i th\u00f4ng tin sai l\u1ec7ch t\u1ed3n t\u1ea1i. C\u00e1c con s\u1ed1 li\u00ean quan, c\u00f9ng ngu\u1ed3n c\u1ee7a ch\u00fang:<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3702\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/traget-5-ohms-or-less.webp\" alt=\"m\u1ee5c ti\u00eau 5 ohm ho\u1eb7c th\u1ea5p h\u01a1n\" width=\"1448\" height=\"1086\" \/><\/p>\n<table>\n<thead>\n<tr>\n<th>Ti\u00eau chu\u1ea9n \/ H\u01b0\u1edbng d\u1eabn<\/th>\n<th>Gi\u00e1 tr\u1ecb<\/th>\n<th>\u00c1p d\u1ee5ng cho<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>NEC 250.53 (NFPA 70)<\/td>\n<td>25 \u00f4m<\/td>\n<td>\u0110i\u1ec7n c\u1ef1c thanh\/t\u1ea5m \u0111\u01a1n \u2014 n\u1ebfu ki\u1ec3m tra \u0111i\u1ec7n tr\u1edf \u1edf m\u1ee9c 25\u03a9 ho\u1eb7c th\u1ea5p h\u01a1n, kh\u00f4ng c\u1ea7n \u0111i\u1ec7n c\u1ef1c th\u1ee9 hai<\/td>\n<\/tr>\n<tr>\n<td>M\u1eb7c \u0111\u1ecbnh NEC 250.53<\/td>\n<td>Hai \u0111i\u1ec7n c\u1ef1c<\/td>\n<td>\u0110i\u1ec7n c\u1ef1c thanh\/\u1ed1ng\/t\u1ea5m m\u1eb7c \u0111\u1ecbnh l\u00e0 hai; kh\u00f4ng c\u1ea7n ki\u1ec3m tra 25\u03a9 khi c\u1ea3 hai \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t<\/td>\n<\/tr>\n<tr>\n<td>IEEE Std 142 (S\u00e1ch Xanh)<\/td>\n<td>1\u20135 \u00f4m<\/td>\n<td>\u0110i\u1ec7n tr\u1edf \u0111\u1ea5t \u0111\u01b0\u1ee3c khuy\u1ebfn ngh\u1ecb c\u1ee7a \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t ch\u00ednh cho c\u00e1c h\u1ec7 th\u1ed1ng th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p l\u1edbn<\/td>\n<\/tr>\n<tr>\n<td>IEEE Std 80<\/td>\n<td>5\u20131 ohm<\/td>\n<td>L\u01b0\u1edbi ti\u1ebfp \u0111\u1ea5t tr\u1ea1m bi\u1ebfn \u00e1p \/ nh\u00e0 m\u00e1y ph\u00e1t \u0111i\u1ec7n<\/td>\n<\/tr>\n<tr>\n<td>H\u01b0\u1edbng d\u1eabn ng\u00e0nh NFPA\/IEEE<\/td>\n<td>5 ohms ho\u1eb7c th\u1ea5p h\u01a1n<\/td>\n<td>M\u1ee5c ti\u00eau th\u01b0\u01a1ng m\u1ea1i th\u01b0\u1eddng \u0111\u01b0\u1ee3c tr\u00edch d\u1eabn; ti\u00eau chu\u1ea9n ng\u00e0nh vi\u1ec5n th\u00f4ng<\/td>\n<\/tr>\n<tr>\n<td>Ki\u1ec3m tra ch\u1ea5p nh\u1eadn NETA ATS<\/td>\n<td>5 \u00f4m \/ 1 \u00f4m<\/td>\n<td>\u22645\u03a9 th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p l\u1edbn; \u22641\u03a9 nh\u00e0 m\u00e1y ph\u00e1t \u0111i\u1ec7n\/tr\u1ea1m truy\u1ec1n t\u1ea3i<\/td>\n<\/tr>\n<tr>\n<td>Nh\u00e0 s\u1ea3n xu\u1ea5t thi\u1ebft b\u1ecb<\/td>\n<td>&lt;1 \u0111\u1ebfn 5 ohms<\/td>\n<td>Th\u00f4ng s\u1ed1 thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed nh\u1ea1y c\u1ea3m \/ thi\u1ebft b\u1ecb ch\u1ea9n \u0111o\u00e1n y t\u1ebf<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>S\u1ef1 th\u1eadt quan tr\u1ecdng: kh\u00f4ng c\u00f3 y\u00eau c\u1ea7u n\u00e0o trong NEC r\u1eb1ng \u0111\u1ea5t th\u01b0\u01a1ng m\u1ea1i ph\u1ea3i \u201c25 ohms ho\u1eb7c th\u1ea5p h\u01a1n\u201d. S\u1ed1 25 ch\u1ec9 \u0111\u01b0\u1ee3c \u0111\u01b0a v\u00e0o \u0111\u1ec3 quy\u1ebft \u0111\u1ecbnh xem c\u00f3 \u0111\u1ee7 kho\u1ea3ng c\u00e1ch t\u1eeb ch\u1ec9 m\u1ed9t \u0111i\u1ec7n c\u1ef1c hay kh\u00f4ng. C\u00e1c y\u00eau c\u1ea7u v\u1ec1 hi\u1ec7u su\u1ea5t nh\u01b0 IEEE 142 v\u00e0 c\u00e1c khuy\u1ebfn ngh\u1ecb c\u0169ng nh\u01b0 th\u1ef1c h\u00e0nh c\u1ee7a NETA \u0111\u1ec1 xu\u1ea5t gi\u00e1 tr\u1ecb t\u1eeb 1 \u0111\u1ebfn 5 ohms \u2013 v\u1edbi 5 ohms l\u00e0 gi\u1edbi h\u1ea1n \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng ph\u1ed5 bi\u1ebfn nh\u1ea5t.<\/p>\n<h2>Quy t\u1eafc 25 Ohm c\u1ee7a NEC \u2014 \u00dd ngh\u0129a th\u1ef1c s\u1ef1 c\u1ee7a n\u00f3<\/h2>\n<p>Theo M\u1ee5c 250.53(A)(2) c\u1ee7a NEC (c\u0169ng nh\u01b0 M\u1ee5c 250-56 c\u1ee7a NEC 2005), m\u00e3 y\u00eau c\u1ea7u l\u1eafp \u0111\u1eb7t hai \u0111i\u1ec7n c\u1ef1c n\u1ed1i \u0111\u1ea5t. Tuy nhi\u00ean, c\u00f3 m\u1ed9t ngo\u1ea1i l\u1ec7 quan tr\u1ecdng n\u00eau r\u1eb1ng m\u1ed9t \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n \u0111\u01b0\u1ee3c ph\u00e9p n\u1ebfu n\u00f3 \u0111\u00e1p \u1ee9ng \u0111i\u1ec7n tr\u1edf n\u1ed1i \u0111\u1ea5t y\u00eau c\u1ea7u l\u00e0 25 ohms ho\u1eb7c th\u1ea5p h\u01a1n. Th\u1eadt kh\u00f4ng may, \u0111i\u1ec1u n\u00e0y th\u01b0\u1eddng b\u1ecb hi\u1ec3u sai l\u00e0 c\u00f3 th\u1ec3 ch\u1ec9 l\u1eafp m\u1ed9t \u0111i\u1ec7n c\u1ef1c, ki\u1ec3m tra \u0111i\u1ec7n tr\u1edf c\u1ee7a n\u00f3, v\u00e0 sau \u0111\u00f3 th\u00eam \u0111i\u1ec7n c\u1ef1c th\u1ee9 hai n\u1ebfu \u0111i\u1ec7n c\u1ef1c \u0111\u1ea7u ti\u00ean kh\u00f4ng \u0111\u00e1p \u1ee9ng y\u00eau c\u1ea7u \u0111i\u1ec7n tr\u1edf 25 ohms.<\/p>\n<p>Th\u1ef1c t\u1ebf, ph\u00e2n t\u00edch nh\u01b0 sau:<\/p>\n<ul>\n<li>M\u1eb7c \u0111\u1ecbnh = hai \u0111i\u1ec7n c\u1ef1c \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t c\u00e1ch nhau \u00edt nh\u1ea5t 6 feet.<\/li>\n<li>\u0110\u01b0\u1ee3c ph\u00e9p = m\u1ed9t \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n \u0111\u01b0\u1ee3c ki\u1ec3m tra \u0111i\u1ec7n tr\u1edf \u0111\u00fang c\u00e1ch x\u00e1c minh r\u1eb1ng \u0111i\u1ec7n tr\u1edf n\u1ed1i \u0111\u1ea5t l\u00e0 25\u03a9 ho\u1eb7c th\u1ea5p h\u01a1n.<\/li>\n<\/ul>\n<p>Trong tr\u01b0\u1eddng h\u1ee3p \u0111i\u1ec7n c\u1ef1c th\u1ee9 hai \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t, t\u1ed5 h\u1ee3p n\u00e0y kh\u00f4ng c\u1ea7n ph\u1ea3i \u0111\u00e1p \u1ee9ng \u0111i\u1ec1u ki\u1ec7n 25 ohm \u2014 v\u00ec \u0111i\u1ec7n c\u1ef1c th\u1ee9 hai \u0111\u01b0\u1ee3c coi l\u00e0 \u0111\u00e3 tu\u00e2n th\u1ee7 y\u00eau c\u1ea7u c\u1ee7a NEC khi \u0111\u01b0\u1ee3c l\u1eafp \u0111\u1eb7t.<\/p>\n<h2>IEEE 142 (S\u00e1ch Xanh): Khuy\u1ebfn ngh\u1ecb 1\u20135 Ohm<\/h2>\n<p>C\u00e2u h\u1ecfi, \u201c\u0111i\u1ec7n tr\u1edf \u0111\u01b0\u1ee3c khuy\u1ebfn ngh\u1ecb cho m\u1ed9t c\u00f4ng tr\u00ecnh th\u01b0\u01a1ng m\u1ea1i l\u00e0 bao nhi\u00eau?\u201d nh\u1eadn \u0111\u01b0\u1ee3c gi\u1ea3i ph\u00e1p k\u1ef9 thu\u1eadt c\u00f3 th\u1ea9m quy\u1ec1n t\u1eeb IEEE Std 142, \u0111\u01b0\u1ee3c bi\u1ebft \u0111\u1ebfn nh\u01b0 S\u00e1ch Xanh. \u0110\u1ec1 xu\u1ea5t c\u1ee7a n\u00f3 l\u00e0 \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t t\u1eeb 1 \u0111\u1ebfn 5 ohms cho \u0111i\u1ec7n c\u1ef1c n\u1ed1i \u0111\u1ea5t ch\u00ednh trong c\u00e1c h\u1ec7 th\u1ed1ng c\u00f4ng nghi\u1ec7p v\u00e0 th\u01b0\u01a1ng m\u1ea1i l\u1edbn.<\/p>\n<p>L\u00fd do \u01b0u ti\u00ean gi\u00e1 tr\u1ecb \u0111i\u1ec7n tr\u1edf n\u00e0y h\u01a1n 25 ohms l\u00e0 v\u00ec c\u00e1c c\u01a1 s\u1edf th\u01b0\u01a1ng m\u1ea1i th\u01b0\u1eddng \u0111\u01b0\u1ee3c trang b\u1ecb thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed nh\u1ea1y c\u1ea3m, v.v., v\u00e0 do \u0111\u00f3 c\u1ea7n m\u1ed9t tham chi\u1ebfu \u0111\u1ea5t \u1ed5n \u0111\u1ecbnh v\u00e0 tr\u1edf kh\u00e1ng th\u1ea5p, \u0111i\u1ec1u m\u00e0 ch\u1ec9 m\u1ee9c t\u1ed1i thi\u1ec3u theo m\u00e3 kh\u00f4ng \u0111\u1ee7. Vi\u1ec7c c\u00f3 \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t th\u1ea5p nh\u01b0 tr\u00ean cho ph\u00e9p:<\/p>\n<ul>\n<li>D\u00f2ng l\u1ed7i cao h\u01a1n tr\u1edf v\u1ec1 ngu\u1ed3n nhanh h\u01a1n<\/li>\n<li>Gi\u1ea3m t\u0103ng \u0111i\u1ec7n \u00e1p tr\u00ean v\u1ecf thi\u1ebft b\u1ecb trong s\u1ef1 c\u1ed1<\/li>\n<li>T\u1ea3n s\u00e9t t\u1ed1t h\u01a1n<\/li>\n<li>Gi\u1ea3m nhi\u1ec5u \u0111i\u1ec7n<\/li>\n<\/ul>\n<p>T\u00f3m l\u1ea1i, m\u00e3 y\u00eau c\u1ea7u 25 ohms; v\u1ec1 m\u1eb7t k\u1ef9 thu\u1eadt, 1-5 ohms l\u00e0 gi\u00e1 tr\u1ecb c\u1ea7n thi\u1ebft cho hi\u1ec7u su\u1ea5t t\u1ed1t.<\/p>\n<p>&nbsp;<\/p>\n<h2>Th\u1ef1c ti\u1ec5n ng\u00e0nh: 5 Ohms l\u00e0 m\u1ee5c ti\u00eau th\u01b0\u01a1ng m\u1ea1i<\/h2>\n<p>Trong th\u1ef1c t\u1ebf, th\u00f4ng tin m\u00e0 h\u1ea7u h\u1ebft m\u1ecdi ng\u01b0\u1eddi nghe \u0111\u01b0\u1ee3c cho c\u00e1c h\u1ec7 th\u1ed1ng th\u01b0\u01a1ng m\u1ea1i l\u00e0 \u201c5 ohms ho\u1eb7c th\u1ea5p h\u01a1n.\u201d \u0110i\u1ec1u n\u00e0y \u0111\u1ebfn t\u1eeb nhi\u1ec1u ngu\u1ed3n kh\u00e1c nhau nh\u01b0ng b\u1ed5 sung cho nhau, ch\u1eb3ng h\u1ea1n nh\u01b0:<\/p>\n<ul>\n<li>c\u00e1c khuy\u1ebfn ngh\u1ecb c\u1ee7a NFPA v\u00e0 IEEE cho 5.0 ohms ho\u1eb7c th\u1ea5p h\u01a1n nh\u01b0 m\u1ed9t m\u1ee5c ti\u00eau t\u1ed1t<\/li>\n<li>c\u00e1c ph\u01b0\u01a1ng ph\u00e1p trong vi\u1ec5n th\u00f4ng (5 ohms ho\u1eb7c th\u1ea5p h\u01a1n cho n\u1ed1i \u0111\u1ea5t v\u00e0 li\u00ean k\u1ebft)<\/li>\n<li>ti\u00eau chu\u1ea9n c\u1ee7a NETA cho c\u00e1c b\u00e0i ki\u1ec3m tra ch\u1ea5p nh\u1eadn (\u22645 ohms cho h\u1ec7 th\u1ed1ng th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p; \u22641 ohm cho nh\u00e0 m\u00e1y \u0111i\u1ec7n\/tr\u1ea1m truy\u1ec1n t\u1ea3i)<\/li>\n<li>c\u00e1c con s\u1ed1 \u0111\u01b0\u1ee3c \u0111\u01b0a ra b\u1edfi c\u00e1c nh\u00e0 s\u1ea3n xu\u1ea5t thi\u1ebft b\u1ecb kh\u00e1c nhau (t\u1eeb 1 \u0111\u1ebfn 5 ohms cho thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed nh\u1ea1y c\u1ea3m)<\/li>\n<\/ul>\n<p>Theo khuy\u1ebfn ngh\u1ecb chung c\u1ee7a c\u00e1c k\u1ef9 s\u01b0 v\u00e0 ng\u01b0\u1eddi ki\u1ec3m tra kh\u00e1c nhau, 5 ohms ho\u1eb7c th\u1ea5p h\u01a1n l\u00e0 t\u1ed1t cho c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i, trong khi gi\u00e1 tr\u1ecb trung b\u00ecnh cho c\u00e1c tr\u1ea1m bi\u1ebfn \u00e1p l\u00e0 1 ohm ho\u1eb7c th\u1ea5p h\u01a1n. \u0110\u00e2y kh\u00f4ng ph\u1ea3i l\u00e0 y\u00eau c\u1ea7u c\u1ee7a NEC, nh\u01b0ng l\u00e0 c\u00e1c th\u1ef1c h\u00e0nh t\u1ed1t nh\u1ea5t m\u00e0 nhi\u1ec1u nh\u00e0 thi\u1ebft k\u1ebf tu\u00e2n theo v\u00e0 \u0111\u01b0\u1ee3c ki\u1ec3m tra.<\/p>\n<h2>C\u00f3 Ph\u1ea1m Vi An To\u00e0n Kh\u00f4ng? Hi\u1ec3u V\u1ec1 C\u00e1c Con S\u1ed1<\/h2>\n<p>D\u01b0\u1edbi \u0111\u00e2y l\u00e0 c\u00e1ch di\u1ec5n gi\u1ea3i c\u00e1c ph\u00e9p \u0111o \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t trong th\u1ef1c t\u1ebf:<\/p>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3703\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/Is-There-a-Safe-Range.webp\" alt=\"C\u00f3 Ph\u1ea1m Vi An To\u00e0n Kh\u00f4ng? Hi\u1ec3u V\u1ec1 C\u00e1c Con S\u1ed1\" width=\"1448\" height=\"1086\" \/><\/p>\n<table>\n<thead>\n<tr>\n<th>\u0110i\u1ec7n tr\u1edf<\/th>\n<th>Di\u1ec5n gi\u1ea3i<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>&lt; 1 \u00f4m<\/td>\n<td>Xu\u1ea5t s\u1eafc \u2014 \u0111i\u1ec3n h\u00ecnh cho c\u00e1c l\u01b0\u1edbi l\u1edbn, tr\u1ea1m bi\u1ebfn \u00e1p, \u0111i\u1ec7n c\u1ef1c m\u1eadt \u0111\u1ed9 cao<\/td>\n<\/tr>\n<tr>\n<td>1\u20135 \u00f4m<\/td>\n<td>T\u1ed1t \u2014 ph\u1ea1m vi khuy\u1ebfn ngh\u1ecb cho th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p (IEEE 142)<\/td>\n<\/tr>\n<tr>\n<td>5\u201310 ohm<\/td>\n<td>Ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c cho nhi\u1ec1u l\u1eafp \u0111\u1eb7t, nh\u01b0ng n\u00ean c\u1ea3i thi\u1ec7n cho t\u1ea3i nh\u1ea1y c\u1ea3m<\/td>\n<\/tr>\n<tr>\n<td>10\u201325 ohm<\/td>\n<td>\u0110\u00e1p \u1ee9ng ng\u01b0\u1ee1ng \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n NEC nh\u01b0ng gi\u1edbi h\u1ea1n cho \u0111i\u1ec7n t\u1eed th\u01b0\u01a1ng m\u1ea1i; c\u1ea7n \u0111i\u1ec1u tra<\/td>\n<\/tr>\n<tr>\n<td>25\u2013100 ohm<\/td>\n<td>K\u00e9m \u2014 v\u01b0\u1ee3t gi\u1edbi h\u1ea1n \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n NEC; c\u00f3 th\u1ec3 c\u1ea7n nhi\u1ec1u \u0111i\u1ec7n c\u1ef1c ho\u1eb7c x\u1eed l\u00fd<\/td>\n<\/tr>\n<tr>\n<td>&gt; 100 ohm<\/td>\n<td>R\u1ea5t k\u00e9m \u2014 kh\u00f4ng ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c cho b\u1ea5t k\u1ef3 l\u1eafp \u0111\u1eb7t c\u1ed1 \u0111\u1ecbnh n\u00e0o; c\u1ea7n l\u00e0m l\u1ea1i<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>C\u1ea3nh b\u00e1o ch\u00ednh nh\u01b0 sau: kh\u00f4ng c\u00f3 m\u1ed9t gi\u00e1 tr\u1ecb \u201can to\u00e0n\u201d chung \u00e1p d\u1ee5ng cho m\u1ecdi t\u00ecnh hu\u1ed1ng t\u1eeb g\u00f3c \u0111\u1ed9 an to\u00e0n \u2014 n\u00f3 c\u00f2n b\u1ecb \u1ea3nh h\u01b0\u1edfng b\u1edfi c\u00e1c y\u1ebfu t\u1ed1 kh\u00e1c nh\u01b0 d\u00f2ng s\u1ef1 c\u1ed1 \u0111\u1ea5t, \u0111i\u1ec1u ki\u1ec7n \u0111\u1ea5t v\u00e0 m\u1ea1ch th\u1ef1c t\u1ebf. Ch\u1ea5t l\u01b0\u1ee3ng \u0111i\u1ec7n tr\u1edf n\u1ed1i \u0111\u1ea5t \u0111i\u1ec7n c\u1ef1c ch\u1ec9 l\u00e0 m\u1ed9t ph\u1ea7n c\u1ee7a v\u1ea5n \u0111\u1ec1; t\u00ednh to\u00e0n v\u1eb9n c\u1ee7a to\u00e0n b\u1ed9 h\u1ec7 th\u1ed1ng n\u1ed1i \u0111\u1ea5t c\u0169ng quan tr\u1ecdng kh\u00f4ng k\u00e9m. M\u1ed9t \u0111i\u1ec7n c\u1ef1c ho\u00e0n h\u1ea3o 2 Ohm kh\u00f4ng c\u00f3 gi\u00e1 tr\u1ecb n\u1ebfu d\u00e2y d\u1eabn n\u1ed1i \u0111\u1ea5t c\u1ee7a thi\u1ebft b\u1ecb b\u1ecb cong ho\u1eb7c \u0103n m\u00f2n.<\/p>\n<h2 id=\"is-20-ohms\">\u0110i\u1ec7n tr\u1edf 20 Ohm c\u00f3 x\u1ea5u kh\u00f4ng? Di\u1ec5n gi\u1ea3i ph\u00e9p \u0111o c\u1ee7a b\u1ea1n<\/h2>\n<p>M\u1ee9c \u0111i\u1ec7n tr\u1edf 20 ohm kh\u00f4ng \u0111\u01b0\u1ee3c \u0111\u00e1nh gi\u00e1 t\u00edch c\u1ef1c trong m\u00e3 x\u00e2y d\u1ef1ng th\u01b0\u01a1ng m\u1ea1i, nh\u01b0ng c\u0169ng kh\u00f4ng c\u00f3 vi ph\u1ea1m m\u00e3 n\u00e0o li\u00ean quan \u0111\u1ebfn gi\u00e1 tr\u1ecb \u0111\u00f3, do \u0111\u00f3:<\/p>\n<ul>\n<li>Ti\u00eau chu\u1ea9n NEC: M\u1ee9c n\u00e0y th\u1ea5p h\u01a1n gi\u00e1 tr\u1ecb t\u1ed1i \u0111a \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n \u0111\u01b0\u1ee3c x\u00e1c \u0111\u1ecbnh b\u1edfi lu\u1eadt tr\u00ean. Tuy nhi\u00ean, m\u1ee9c \u0111i\u1ec7n tr\u1edf 20 ohm v\u1eabn g\u1ea7n v\u01b0\u1ee3t ti\u00eau chu\u1ea9n, t\u00f9y thu\u1ed9c v\u00e0o s\u1ef1 t\u0103ng gi\u1ea3m \u0111\u1ed9 \u1ea9m theo m\u00f9a trong \u0111\u1ea5t.<\/li>\n<li>Ti\u00eau chu\u1ea9n IEEE 142: D\u1ef1a tr\u00ean ti\u00eau chu\u1ea9n n\u00e0y, m\u1ee9c \u0111i\u1ec7n tr\u1edf 20 ohm v\u01b0\u1ee3t gi\u00e1 tr\u1ecb khuy\u1ebfn ngh\u1ecb 1-5 ohm, ngh\u0129a l\u00e0 m\u1ed9t s\u1ed1 thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed, nh\u01b0 thi\u1ebft b\u1ecb ng\u0103n ng\u1eeba s\u1ef1 c\u1ed1 t\u0103ng \u00e1p, c\u00f3 th\u1ec3 b\u1ecb h\u01b0 h\u1ecfng do m\u1ee9c n\u1ed1i \u0111\u1ea5t kh\u00f4ng ph\u00f9 h\u1ee3p.<\/li>\n<\/ul>\n<p>V\u1ec1 m\u1eb7t th\u1ef1c t\u1ebf, b\u1ea5t k\u1ef3 t\u1ed5 ch\u1ee9c th\u01b0\u01a1ng m\u1ea1i n\u00e0o c\u0169ng s\u1ebd \u0111\u1ea3m b\u1ea3o n\u1ed1i \u0111\u1ea5t \u0111\u00e1p \u1ee9ng c\u00e1c ti\u00eau chu\u1ea9n \u0111\u00e3 \u0111\u1eb7t ra.<\/p>\n<p>K\u1ebft lu\u1eadn: N\u00f3i chung, \u0111i\u1ec7n tr\u1edf 20 ohm c\u00f3 th\u1ec3 kh\u00f4ng \u0111e d\u1ecda \u0111\u1ebfn s\u1ef1 an to\u00e0n c\u1ee7a t\u00f2a nh\u00e0, nh\u01b0ng v\u1eabn qu\u00e1 cao cho m\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i; do \u0111\u00f3, c\u1ea7n \u0111\u01b0\u1ee3c c\u1ea3i thi\u1ec7n.<\/p>\n<h2>C\u00e1c y\u00eau c\u1ea7u th\u01b0\u01a1ng m\u1ea1i kh\u00e1c: \u1ed4 c\u1eafm &amp; Li\u00ean k\u1ebft<\/h2>\n<p>\u0110i\u1ec7n tr\u1edf \u0111\u1ea5t l\u00e0 m\u1ed9t ph\u1ea7n c\u1ee7a an to\u00e0n \u0111i\u1ec7n th\u01b0\u01a1ng m\u1ea1i. C\u00e1c y\u00eau c\u1ea7u c\u1ee7a M\u00e3 \u0111i\u1ec7n qu\u1ed1c gia (NEC) nh\u01b0 sau:<\/p>\n<ul>\n<li>\u0110\u1eb7c \u0111i\u1ec3m c\u1ee7a \u1ed5 c\u1eafm th\u01b0\u01a1ng m\u1ea1i (NEC 406, 210.52, 210.8): \u1ed4 c\u1eafm th\u01b0\u01a1ng m\u1ea1i ph\u1ea3i \u0111\u01b0\u1ee3c ch\u1ec9 \u0111\u1ecbnh l\u00e0 lo\u1ea1i 125V, 15A v\u00e0\/ho\u1eb7c 20A, c\u1ea7n cung c\u1ea5p b\u1ea3o v\u1ec7 GFCI t\u1ea1i m\u1ed9t s\u1ed1 v\u1ecb tr\u00ed nh\u1ea5t \u0111\u1ecbnh (ph\u00f2ng t\u1eafm, m\u00e1i nh\u00e0, b\u1ebfp, ngo\u00e0i tr\u1eddi theo 210.8(B)), t\u1ea5t c\u1ea3 \u1ed5 c\u1eafm s\u1ebd \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i v\u1edbi h\u1ed9p kim lo\u1ea1i v\u00e0 m\u1ed7i \u1ed5 c\u1eafm ph\u1ea3i \u0111\u1ea3m b\u1ea3o \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i v\u1edbi d\u00e2y d\u1eabn n\u1ed1i \u0111\u1ea5t.<\/li>\n<li>Qu\u00e1 tr\u00ecnh li\u00ean k\u1ebft (NEC 250.102-250.104): C\u1ea7n hi\u1ec3u r\u1eb1ng t\u1ea5t c\u1ea3 c\u00e1c b\u1ed9 ph\u1eadn kim lo\u1ea1i c\u00f3 th\u1ec3 mang \u0111i\u1ec7n nh\u01b0 \u1ed1ng d\u1eabn, thi\u1ebft b\u1ecb khung, th\u00e9p k\u1ebft c\u1ea5u, thi\u1ebft b\u1ecb b\u01a1m ph\u1ea3i \u0111\u01b0\u1ee3c li\u00ean k\u1ebft v\u1edbi h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t. C\u1ea7n l\u01b0u \u00fd r\u1eb1ng ki\u1ec3m tra t\u00ednh li\u00ean t\u1ee5c c\u1ee7a li\u00ean k\u1ebft s\u1ebd \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n ri\u00eang bi\u1ec7t v\u1edbi \u0111i\u1ec7n tr\u1edf \u0111i\u1ec7n c\u1ef1c (\u0111i\u1ec7n tr\u1edf \u0111i\u1ec3m-\u0111i\u1ec3m kh\u00f4ng \u0111\u01b0\u1ee3c v\u01b0\u1ee3t qu\u00e1 0,5 ohm khi thi\u1ebft b\u1ecb \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i v\u1edbi h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t).<\/li>\n<li>D\u00e2y d\u1eabn \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t (NEC 250.66): C\u00e1c \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t ph\u1ea3i \u0111\u01b0\u1ee3c k\u00edch th\u01b0\u1edbc ph\u00f9 h\u1ee3p theo d\u1ecbch v\u1ee5 kh\u00f4ng v\u01b0\u1ee3t qu\u00e1 \u0111\u01b0\u1eddng k\u00ednh t\u1ed1i \u0111a v\u00e0 ph\u1ea3i k\u1ebft n\u1ed1i h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t v\u1edbi thi\u1ebft b\u1ecb d\u1ecbch v\u1ee5.<\/li>\n<\/ul>\n<p>N\u1ebfu b\u1ea1n c\u0169ng \u0111ang ki\u1ec3m tra c\u00e1c thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 tr\u00ean m\u1ea1ch, gi\u1ea3i th\u00edch c\u1ee7a ch\u00fang t\u00f4i v\u1ec1 <a href=\"https:\/\/huyuglobal.com\/vi\/blog\/circuit-breaker-and-ground-fault-circuit-interrupter\/\" rel=\"nofollow\">b\u1ed9 ng\u1eaft m\u1ea1ch so v\u1edbi b\u1ed9 ng\u1eaft m\u1ea1ch s\u1ef1 c\u1ed1 n\u1ed1i \u0111\u1ea5t<\/a> l\u00e0m r\u00f5 thi\u1ebft b\u1ecb b\u1ea3o v\u1ec7 n\u00e0o th\u1ef1c hi\u1ec7n ch\u1ee9c n\u0103ng g\u00ec trong b\u1ea3ng \u0111i\u1ec7n th\u01b0\u01a1ng m\u1ea1i.<\/p>\n<h2>\u0110i\u1ec7n tr\u1edf \u0111i\u1ec7n cao \u0111\u01b0\u1ee3c t\u00ednh nh\u01b0 th\u1ebf n\u00e0o?<\/h2>\n<p>B\u1ed1i c\u1ea3nh \u0111\u00f3ng vai tr\u00f2 trong vi\u1ec7c hi\u1ec3u \u201c\u0111i\u1ec7n tr\u1edf cao\u201d c\u00f3 ngh\u0129a l\u00e0 g\u00ec:<\/p>\n<ul>\n<li>Khi \u0111o \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t, n\u00f3 c\u00f3 ngh\u0129a l\u00e0 l\u1edbn h\u01a1n kho\u1ea3ng 25 ohm (v\u00ed d\u1ee5, 100 ohm ho\u1eb7c l\u1edbn h\u01a1n l\u00e0 gi\u00e1 tr\u1ecb r\u1ea5t cao). M\u1ee9c \u0111i\u1ec7n tr\u1edf \u201cl\u00fd t\u01b0\u1edfng\u201d l\u00e0 1-5 ohm.<\/li>\n<li>V\u1ec1 t\u00ednh li\u00ean t\u1ee5c c\u1ee7a ti\u1ebfp \u0111\u1ea5t, b\u1ea5t k\u1ef3 gi\u00e1 tr\u1ecb n\u00e0o l\u1edbn h\u01a1n 0,5 ohm \u0111\u1ec1u ch\u1ec9 ra l\u1ed7i. K\u1ebft n\u1ed1i gi\u1eefa thi\u1ebft b\u1ecb v\u00e0 \u0111\u1ea5t n\u00ean g\u1ea7n nh\u01b0 b\u1eb1ng kh\u00f4ng.<\/li>\n<li>\u0110\u1ed1i v\u1edbi \u0111i\u1ec7n tr\u1edf c\u00e1ch \u0111i\u1ec7n, gi\u00e1 tr\u1ecb \u0111i\u1ec7n tr\u1edf cao c\u00f3 ngh\u0129a l\u00e0 \u0111i\u1ec7n tr\u1edf t\u1ed1t v\u00ec n\u00f3 \u0111\u01b0\u1ee3c \u0111o b\u1eb1ng mega v\u00e0 gigaohm, trong \u0111\u00f3 b\u1ea5t k\u1ef3 gi\u00e1 tr\u1ecb n\u00e0o d\u01b0\u1edbi 1 M\u03a9 \u0111\u1ec1u ch\u1ec9 ra kh\u1ea3 n\u0103ng cao b\u1ecb h\u1ecfng.<\/li>\n<\/ul>\n<p>T\u00f3m l\u1ea1i, \u201c\u0111i\u1ec7n tr\u1edf cao\u201d h\u1ea7u nh\u01b0 lu\u00f4n c\u00f3 ngh\u0129a l\u00e0 c\u00f3 v\u1ea5n \u0111\u1ec1 (\u0111\u1ed1i v\u1edbi ti\u1ebfp \u0111\u1ea5t) nh\u01b0ng c\u00f3 th\u1ec3 c\u00f3 ngh\u0129a l\u00e0 t\u00ecnh tr\u1ea1ng t\u1ed1t (\u0111\u1ed1i v\u1edbi c\u00e1ch \u0111i\u1ec7n). Lu\u00f4n \u0111\u1ea3m b\u1ea3o r\u00f5 r\u00e0ng \u0111ang n\u00f3i v\u1ec1 \u0111i\u1ec1u g\u00ec khi s\u1eed d\u1ee5ng thu\u1eadt ng\u1eef \u201c\u0111i\u1ec7n tr\u1edf cao\u201d.<\/p>\n<h2>C\u00e1c y\u1ebfu t\u1ed1 \u1ea3nh h\u01b0\u1edfng \u0111\u1ebfn \u0111i\u1ec7n tr\u1edf ti\u1ebfp \u0111\u1ea5t<\/h2>\n<p>\u0110i\u1ec7n tr\u1edf ti\u1ebfp \u0111\u1ea5t kh\u00f4ng ph\u1ea3i l\u00e0 gi\u00e1 tr\u1ecb c\u1ed1 \u0111\u1ecbnh. N\u00f3 thay \u0111\u1ed5i theo ho\u00e0n c\u1ea3nh:<\/p>\n<ul>\n<li>\u0110i\u1ec7n tr\u1edf su\u1ea5t \u0111\u1ea5t: \u0110\u1ea5t s\u00e9t\/\u0111\u1ea5t m\u00f9n (10\u2013100 \u03a9\u00b7m) c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t th\u1ea5p h\u01a1n so v\u1edbi c\u00e1t\/s\u1ecfi (1.000\u201310.000 \u03a9\u00b7m).<\/li>\n<li>\u0110\u1ed9 \u1ea9m: \u0110\u1ea5t \u1ea9m c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t th\u1ea5p h\u01a1n trong khi th\u1eddi ti\u1ebft kh\u00f4 l\u00e0m t\u0103ng \u0111i\u1ec7n tr\u1edf r\u1ea5t nhi\u1ec1u.<\/li>\n<li>Nhi\u1ec7t \u0111\u1ed9: \u0110\u1ea5t l\u1ea1nh c\u00f3 \u0111i\u1ec7n tr\u1edf su\u1ea5t cao h\u01a1n nhi\u1ec1u.<\/li>\n<li>\u0110\u1ed9 s\u00e2u v\u00e0 ti\u1ebft di\u1ec7n \u0111i\u1ec7n c\u1ef1c: \u0110i\u1ec7n c\u1ef1c d\u00e0i h\u01a1n v\u00e0 t\u1ea5m \u0111i\u1ec7n c\u1ef1c l\u1edbn h\u01a1n s\u1ebd \u0111i s\u00e2u h\u01a1n v\u00e0o \u0111\u1ea5t.<\/li>\n<li>S\u1ed1 l\u01b0\u1ee3ng v\u00e0 kho\u1ea3ng c\u00e1ch gi\u1eefa c\u00e1c \u0111i\u1ec7n c\u1ef1c: S\u1ed1 l\u01b0\u1ee3ng \u0111i\u1ec7n c\u1ef1c c\u00e0ng nhi\u1ec1u v\u00e0 kho\u1ea3ng c\u00e1ch c\u00e0ng xa th\u00ec \u0111i\u1ec7n tr\u1edf c\u00e0ng th\u1ea5p.<\/li>\n<li>V\u1eadt li\u1ec7u \u0111i\u1ec7n c\u1ef1c v\u00e0 \u0103n m\u00f2n: \u0110i\u1ec7n c\u1ef1c c\u00e0ng \u1edf l\u00e2u trong \u0111\u1ea5t th\u00ec c\u00e0ng b\u1ecb \u0103n m\u00f2n nhi\u1ec1u v\u00e0 \u0111i\u1ec7n tr\u1edf s\u1ebd t\u0103ng.<\/li>\n<\/ul>\n<p style=\"text-align: center;\"><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-3704\" src=\"https:\/\/huyuglobal.com\/wp-content\/uploads\/2026\/08\/How-to-Achieve-a-Low-Resistance-Ground.webp\" alt=\"C\u00e1ch \u0111\u1ea1t \u0111\u01b0\u1ee3c \u0111i\u1ec7n tr\u1edf ti\u1ebfp \u0111\u1ea5t th\u1ea5p\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>C\u00e1ch \u0111\u1ea1t \u0111\u01b0\u1ee3c \u0111i\u1ec7n tr\u1edf ti\u1ebfp \u0111\u1ea5t th\u1ea5p<\/h2>\n<p>Trong tr\u01b0\u1eddng h\u1ee3p ti\u1ebfp \u0111\u1ea5t th\u01b0\u01a1ng m\u1ea1i c\u1ee7a b\u1ea1n qu\u00e1 cao, \u0111\u00e2y l\u00e0 danh s\u00e1ch x\u1ebfp h\u1ea1ng c\u00e1c gi\u1ea3i ph\u00e1p hi\u1ec7u qu\u1ea3 v\u1ec1 chi ph\u00ed nh\u1ea5t:<\/p>\n<ul>\n<li>Th\u00eam c\u1ecdc ti\u1ebfp \u0111\u1ea5t: Th\u00eam m\u1ed9t c\u1ecdc ti\u1ebfp \u0111\u1ea5t th\u1ee9 hai, \u0111\u1eb7t c\u00e1ch c\u1ecdc \u0111\u1ea7u ti\u00ean 8 feet, s\u1ebd gi\u1ea3m \u0111\u00e1ng k\u1ec3 \u0111i\u1ec7n tr\u1edf. Ti\u1ebfp t\u1ee5c th\u00eam c\u00e1c c\u1ecdc b\u1ed5 sung cho \u0111\u1ebfn khi \u0111\u1ea1t \u0111\u01b0\u1ee3c \u0111i\u1ec7n tr\u1edf \u0111\u00fang (l\u1ee3i \u00edch gi\u1ea3m d\u1ea7n v\u1edbi m\u1ed7i c\u1ecdc th\u00eam).<\/li>\n<li>S\u1eed d\u1ee5ng c\u1ecdc l\u1edbn h\u01a1n ho\u1eb7c d\u00e0i h\u01a1n: S\u1eed d\u1ee5ng c\u1ecdc d\u00e0i h\u01a1n (10 feet) ho\u1eb7c c\u1ecdc d\u00e0y ho\u1eb7c \u0111i\u1ec7n c\u1ef1c t\u1ea5m s\u1ebd gi\u00fap ti\u1ebfp c\u1eadn \u0111\u1ea5t s\u00e2u h\u01a1n v\u00e0 c\u00f3 \u0111i\u1ec7n tr\u1edf th\u1ea5p h\u01a1n.<\/li>\n<li>C\u1ea3i thi\u1ec7n k\u1ebft n\u1ed1i \u0111\u1ea5t: L\u1ea5p l\u1ea1i b\u1eb1ng v\u1eadt li\u1ec7u d\u1eabn \u0111i\u1ec7n ho\u1eb7c ph\u1ee5 gia h\u00f3a h\u1ecdc xung quanh c\u1ecdc s\u1ebd c\u1ea3i thi\u1ec7n k\u1ebft n\u1ed1i c\u1ee7a n\u00f3 v\u1edbi \u0111\u1ea5t.<\/li>\n<li>T\u1ea1o v\u00f2ng \u0111\u1ea5t ho\u1eb7c l\u01b0\u1edbi: D\u00e2y d\u1eabn \u0111\u1ed3ng ng\u1ea7m bao quanh c\u1ea5u tr\u00fac t\u1ea1o ra khu v\u1ef1c k\u1ebft n\u1ed1i l\u1edbn h\u01a1n (gi\u1ea3i ph\u00e1p n\u00e0y \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng r\u1ed9ng r\u00e3i trong l\u0129nh v\u1ef1c th\u01b0\u01a1ng m\u1ea1i\/c\u00f4ng nghi\u1ec7p).<\/li>\n<li>S\u1eed d\u1ee5ng \u0111i\u1ec7n c\u1ef1c b\u1ecdc b\u00ea t\u00f4ng (\u0111\u1ea5t Ufer): Th\u00e9p c\u1ed1t b\u00ea t\u00f4ng v\u00e0 d\u00e2y d\u1eabn nh\u00fang trong b\u00ea t\u00f4ng cho th\u1ea5y \u0111\u1eb7c t\u00ednh d\u1eabn \u0111i\u1ec7n xu\u1ea5t s\u1eafc v\u00e0 \u0111\u00e1ng tin c\u1eady.<\/li>\n<li>K\u1ebft n\u1ed1i v\u1edbi c\u00e1c b\u1ed9 ph\u1eadn th\u00e9p c\u1ee7a t\u00f2a nh\u00e0 v\u00e0 \u1ed1ng n\u01b0\u1edbc: K\u1ebft n\u1ed1i v\u1edbi th\u00e9p k\u1ebft c\u1ea5u kim lo\u1ea1i v\u00e0 \u1ed1ng n\u01b0\u1edbc ng\u1ea7m (n\u1ebfu c\u00f3) cung c\u1ea5p c\u00e1c ph\u01b0\u01a1ng th\u1ee9c d\u1eabn \u0111i\u1ec7n b\u1ed5 sung.<\/li>\n<\/ul>\n<p>H\u00e3y ch\u1eafc ch\u1eafn ki\u1ec3m tra m\u1ed7i khi b\u1ea1n thay \u0111\u1ed5i h\u1ec7 th\u1ed1ng, nh\u01b0ng l\u01b0u \u00fd r\u1eb1ng NEC kh\u00f4ng y\u00eau c\u1ea7u ki\u1ec3m tra l\u1ea1i h\u1ec7 th\u1ed1ng hai \u0111i\u1ec7n c\u1ef1c.<\/p>\n<h2>C\u00e1ch ki\u1ec3m tra \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t<\/h2>\n<p>Vi\u1ec7c ki\u1ec3m tra \u0111\u1ea5t ph\u1ea3i \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi nh\u1eefng ng\u01b0\u1eddi c\u00f3 tr\u00ecnh \u0111\u1ed9 chuy\u00ean m\u00f4n cho c\u00f4ng vi\u1ec7c n\u00e0y. C\u00e1c ph\u01b0\u01a1ng ph\u00e1p ch\u00ednh v\u00e0 ph\u1ed5 bi\u1ebfn l\u00e0:<\/p>\n<ul>\n<li>Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3m th\u1ebf (th\u01b0\u1eddng \u0111\u01b0\u1ee3c bi\u1ebft \u0111\u1ebfn l\u00e0 ki\u1ec3m tra ba \u0111i\u1ec3m): Ph\u01b0\u01a1ng ph\u00e1p gi\u1ea3m th\u1ebf bao g\u1ed3m vi\u1ec7c s\u1eed d\u1ee5ng hai c\u1ecdc t\u1ea1m th\u1eddi v\u00e0 \u0111o \u0111i\u1ec7n tr\u1edf v\u1edbi kho\u1ea3ng c\u00e1ch t\u0103ng d\u1ea7n. \u0110\u00e2y l\u00e0 k\u1ef9 thu\u1eadt ch\u00ednh x\u00e1c nh\u1ea5t \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho c\u00e1c l\u1eafp \u0111\u1eb7t nh\u1ecf \u0111\u1ebfn trung b\u00ecnh.<\/li>\n<li>Ki\u1ec3m tra k\u1eb9p (ho\u1eb7c c\u1ea3m \u1ee9ng): Ph\u01b0\u01a1ng ph\u00e1p k\u1eb9p bao g\u1ed3m vi\u1ec7c k\u1eb9p quanh thanh\/c\u00e1p d\u1eabn \u0111\u1ec3 \u0111o \u0111i\u1ec7n tr\u1edf v\u00f2ng m\u00e0 kh\u00f4ng c\u1ea7n ng\u1eaft v\u00f2ng. Ph\u01b0\u01a1ng ph\u00e1p n\u00e0y c\u00f3 l\u1ee3i cho c\u00e1c l\u1eafp \u0111\u1eb7t \u0111\u00e3 t\u1ed3n t\u1ea1i nh\u01b0ng y\u00eau c\u1ea7u to\u00e0n b\u1ed9 v\u00f2ng ph\u1ea3i \u0111\u01b0\u1ee3c k\u1ebft n\u1ed1i.<\/li>\n<li>Ki\u1ec3m tra hai \u0111i\u1ec3m: Ph\u01b0\u01a1ng ph\u00e1p hai \u0111i\u1ec3m \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 \u0111o nhanh so v\u1edbi \u0111i\u1ec7n c\u1ef1c tham chi\u1ebfu \u0111\u00e3 bi\u1ebft: k\u1ef9 thu\u1eadt n\u00e0y k\u00e9m ch\u00ednh x\u00e1c h\u01a1n, do \u0111\u00f3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng trong c\u00e1c t\u00ednh to\u00e1n s\u01a1 b\u1ed9.<\/li>\n<\/ul>\n<p>Vi\u1ec7c ki\u1ec3m tra c\u00f3 nguy hi\u1ec3m, v\u00ec th\u01b0\u1eddng y\u00eau c\u1ea7u c\u00e1ch ly \u0111i\u1ec7n c\u1ef1c, v\u00e0 c\u00f3 th\u1ec3 c\u00f3 d\u00f2ng s\u1ef1 c\u1ed1, c\u00f4ng vi\u1ec7c n\u00e0y kh\u00f4ng n\u00ean do ch\u1ee7 nh\u00e0 th\u00f4ng th\u01b0\u1eddng th\u1ef1c hi\u1ec7n. \u0110\u1ed1i v\u1edbi c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i, vi\u1ec7c v\u1eadn h\u00e0nh v\u00e0 ki\u1ec3m tra \u0111\u1ecbnh k\u1ef3 th\u01b0\u1eddng \u0111\u01b0\u1ee3c th\u1ef1c hi\u1ec7n b\u1edfi c\u00e1c nh\u00e0 th\u1ea7u ho\u1eb7c c\u00f4ng ty chuy\u00ean m\u00f4n theo ti\u00eau chu\u1ea9n NETA.<\/p>\n<h2>C\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n<h3>H\u01b0\u1edbng d\u1eabn n\u00e0o quy \u0111\u1ecbnh \u0111i\u1ec7n tr\u1edf t\u1ed1i \u0111a ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c cho h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t trong c\u00e1c l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i?<\/h3>\n<p>NEC kh\u00f4ng quy \u0111\u1ecbnh m\u1ed9t gi\u00e1 tr\u1ecb t\u1ed1i \u0111a duy nh\u1ea5t. Y\u00eau c\u1ea7u 25 ohm \u0111\u01b0\u1ee3c n\u00eau trong NEC 250.53 ch\u1ec9 \u00e1p d\u1ee5ng cho tr\u01b0\u1eddng h\u1ee3p h\u1ec7 th\u1ed1ng m\u1ed9t \u0111i\u1ec7n c\u1ef1c, kh\u00f4ng \u00e1p d\u1ee5ng cho to\u00e0n b\u1ed9 t\u00f2a nh\u00e0. M\u1ed9t ti\u00eau chu\u1ea9n k\u1ef9 thu\u1eadt l\u1edbn l\u00e0 IEEE Std 142 (S\u00e1ch Xanh), \u0111\u1ec1 xu\u1ea5t gi\u00e1 tr\u1ecb \u0111i\u1ec7n tr\u1edf c\u1ee7a \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t ch\u00ednh trong c\u00e1c l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i v\u00e0 c\u00f4ng nghi\u1ec7p l\u1edbn n\u00ean n\u1eb1m trong kho\u1ea3ng 1-5 ohm. Th\u00f4ng th\u01b0\u1eddng, trong th\u1ef1c t\u1ebf v\u00e0 theo ti\u00eau chu\u1ea9n NETA, gi\u00e1 tr\u1ecb 5 ohm \u0111\u01b0\u1ee3c coi l\u00e0 th\u1ecfa \u0111\u00e1ng cho m\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i (1 ohm cho tr\u1ea1m bi\u1ebfn \u00e1p). N\u00f3i chung, NEC ch\u1ec9 ra gi\u1edbi h\u1ea1n theo y\u00eau c\u1ea7u c\u1ee7a m\u00e3, IEEE 142 cung c\u1ea5p ph\u1ea1m vi ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c theo y\u00eau c\u1ea7u k\u1ef9 thu\u1eadt, v\u00e0 sau \u0111\u00f3 5 ohm tr\u1edf th\u00e0nh th\u1ef1c ti\u1ec5n \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn.<\/p>\n<h3>\u0110i\u1ec7n tr\u1edf \u0111\u1ea5t 20 ohm c\u00f3 ph\u1ea3i l\u00e0 x\u1ea5u kh\u00f4ng?<\/h3>\n<p>\u0110i\u1ec7n tr\u1edf 20 ohm kh\u00f4ng nguy hi\u1ec3m t\u1ef1 n\u00f3 nh\u01b0ng l\u00e0 m\u1ee9c ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c \u1edf gi\u1edbi h\u1ea1n cho c\u00e1c t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i. Trong khi ti\u00eau ch\u00ed m\u1ed9t thanh c\u1ee7a NEC l\u00e0 25 ohm \u0111\u01b0\u1ee3c v\u01b0\u1ee3t qua, con s\u1ed1 n\u00e0y cao h\u01a1n m\u1ee9c \u0111\u01b0\u1ee3c IEEE 142 khuy\u1ebfn ngh\u1ecb cho c\u00e1c l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i, l\u00e0 1\uff0d5 ohm, c\u0169ng nh\u01b0 m\u1ee9c \u0111\u01b0\u1ee3c ch\u1ea5p nh\u1eadn ph\u1ed5 bi\u1ebfn l\u00e0 5 ohm. V\u1edbi m\u1ee9c ti\u1ebfp \u0111\u1ea5t \u0111\u00f3, d\u00f2ng s\u1ef1 c\u1ed1 tr\u1edf v\u1ec1 ch\u1eadm h\u01a1n v\u00e0 kh\u00f4ng cung c\u1ea5p kh\u1ea3 n\u0103ng b\u1ea3o v\u1ec7 ch\u1ed1ng s\u00e9t \u0111\u00e1ng k\u1ec3 ho\u1eb7c ti\u1ebfp \u0111\u1ea5t tham chi\u1ebfu cho c\u00e1c thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed nh\u1ea1y c\u1ea3m. V\u00e0 v\u00ec n\u00f3 ch\u1ec9 c\u00e1ch ng\u01b0\u1ee1ng quy chu\u1ea9n m\u1ed9t b\u01b0\u1edbc, m\u1ee9c n\u00e0y c\u00f3 th\u1ec3 t\u0103ng l\u00ean do s\u1ef1 thay \u0111\u1ed5i \u0111i\u1ec1u ki\u1ec7n \u0111\u1ea5t trong c\u00e1c m\u00f9a. Do \u0111\u00f3, h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t n\u00ean \u0111\u01b0\u1ee3c c\u1ea3i thi\u1ec7n trong tr\u01b0\u1eddng h\u1ee3p c\u00e1c l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i.<\/p>\n<h3>Y\u00eau c\u1ea7u \u1ed5 c\u1eafm th\u01b0\u01a1ng m\u1ea1i theo NEC l\u00e0 g\u00ec?<\/h3>\n<p>T\u1ea5t c\u1ea3 \u1ed5 c\u1eafm th\u01b0\u01a1ng m\u1ea1i c\u00f3 \u0111i\u1ec7n \u00e1p \u0111\u1ecbnh m\u1ee9c 125 volt v\u1edbi d\u00f2ng 15 ho\u1eb7c 20 ampe nh\u01b0 quy \u0111\u1ecbnh trong NEC 406, v\u00e0 s\u1ed1 l\u01b0\u1ee3ng t\u1ed1i thi\u1ec3u c\u00f9ng quy t\u1eafc kho\u1ea3ng c\u00e1ch c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c t\u00ecm th\u1ea5y trong 210.52 cho c\u00e1c khu v\u1ef1c chung. B\u1ea3o v\u1ec7 GFCI l\u00e0 b\u1eaft bu\u1ed9c trong c\u00e1c kh\u00f4ng gian th\u01b0\u01a1ng m\u1ea1i nh\u1ea5t \u0111\u1ecbnh theo NEC 210.8(b), nh\u01b0 ph\u00f2ng t\u1eafm, nh\u00e0 b\u1ebfp, m\u00e1i nh\u00e0, ngo\u00e0i tr\u1eddi v\u00e0 khu v\u1ef1c gara\/d\u1ecbch v\u1ee5. T\u1ea5t c\u1ea3 \u1ed5 c\u1eafm ph\u1ea3i \u0111\u01b0\u1ee3c cung c\u1ea5p ti\u1ebfp \u0111\u1ea5t thi\u1ebft b\u1ecb, v\u00e0 c\u00e1c h\u1ed9p kim lo\u1ea1i ph\u1ea3i \u0111\u01b0\u1ee3c ti\u1ebfp \u0111\u1ea5t. \u1ede nhi\u1ec1u n\u01a1i d\u00e0nh cho tr\u1ebb em trong th\u01b0\u01a1ng m\u1ea1i, \u1ed5 c\u1eafm ch\u1ed1ng tr\u1ebb em l\u00e0 b\u1eaft bu\u1ed9c, trong khi m\u1ed9t s\u1ed1 lo\u1ea1i khu v\u1ef1c s\u1eed d\u1ee5ng c\u00f3 quy t\u1eafc ri\u00eang cho \u1ed5 c\u1eafm \u0111\u01b0\u1ee3c cung c\u1ea5p.<\/p>\n<h3>\u0110i\u1ec7n tr\u1edf \u0111i\u1ec7n cao l\u00e0 g\u00ec?<\/h3>\n<p>\u201c\u0110i\u1ec7n tr\u1edf \u0111i\u1ec7n cao\u201d ph\u1ee5 thu\u1ed9c v\u00e0o ph\u00e9p \u0111o \u0111ang \u0111\u01b0\u1ee3c xem x\u00e9t. \u0110\u1ed1i v\u1edbi \u0111i\u1ec7n c\u1ef1c ti\u1ebfp \u0111\u1ea5t, b\u1ea5t k\u1ef3 gi\u00e1 tr\u1ecb n\u00e0o tr\u00ean kho\u1ea3ng 25 ohm \u0111\u01b0\u1ee3c coi l\u00e0 cao, trong khi c\u00e1c con s\u1ed1 tr\u00ean 100 ohm \u0111\u01b0\u1ee3c xem l\u00e0 r\u1ea5t cao. L\u00fd t\u01b0\u1edfng nh\u1ea5t, \u0111i\u1ec7n tr\u1edf n\u00ean n\u1eb1m trong kho\u1ea3ng t\u1eeb 1 \u0111\u1ebfn 5 ohm. V\u1ec1 t\u00ednh li\u00ean t\u1ee5c ti\u1ebfp \u0111\u1ea5t thi\u1ebft b\u1ecb, \u0111i\u1ec7n tr\u1edf \u0111i\u1ec7n kh\u00f4ng n\u00ean v\u01b0\u1ee3t qu\u00e1 0,5 ohm khi \u0111o thi\u1ebft b\u1ecb v\u00e0 \u0111\u1ea5t. Trong c\u00e1ch \u0111i\u1ec7n, \u0111i\u1ec7n tr\u1edf cao l\u00e0 d\u1ea5u hi\u1ec7u t\u00edch c\u1ef1c. \u0110\u1ec3 c\u00e1ch \u0111i\u1ec7n \u0111\u01b0\u1ee3c coi l\u00e0 kh\u1ecfe m\u1ea1nh, n\u00f3 ph\u1ea3i c\u00f3 \u0111i\u1ec7n tr\u1edf h\u00e0ng tri\u1ec7u ohm (M\u03a9) ho\u1eb7c th\u1eadm ch\u00ed h\u00e0ng t\u1ef7 ohm. M\u1ee9c \u0111i\u1ec7n tr\u1edf d\u01b0\u1edbi 1 M\u03a9 cho th\u1ea5y s\u1ef1 suy gi\u1ea3m v\u1edbi nguy c\u01a1 r\u00f2 r\u1ec9.<\/p>\n<h2>T\u00e0i li\u1ec7u tham kh\u1ea3o<\/h2>\n<ul>\n<li><a href=\"https:\/\/www.nfpa.org\/codes-and-standards\/all-codes-and-standards\/list-of-codes-and-standards\/detail?code=70\" rel=\"nofollow noopener\" target=\"_blank\">NFPA 70 \u2014 National Electrical Code (NEC), \u0110i\u1ec1u 250 (Ti\u1ebfp \u0111\u1ea5t &amp; Li\u00ean k\u1ebft), 210.8, 406<\/a><\/li>\n<li><a href=\"https:\/\/standards.ieee.org\/ieee\/142\/4070\/\" rel=\"nofollow noopener\" target=\"_blank\">IEEE Std 142-2007 \u2014 Th\u1ef1c h\u00e0nh khuy\u1ebfn ngh\u1ecb cho ti\u1ebfp \u0111\u1ea5t h\u1ec7 th\u1ed1ng \u0111i\u1ec7n c\u00f4ng nghi\u1ec7p v\u00e0 th\u01b0\u01a1ng m\u1ea1i (Green Book)<\/a><\/li>\n<li><a href=\"https:\/\/standards.ieee.org\/ieee\/81\/4395\/\" rel=\"nofollow noopener\" target=\"_blank\">IEEE Std 81 \u2014 H\u01b0\u1edbng d\u1eabn \u0111o \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t, tr\u1edf kh\u00e1ng \u0111\u1ea5t v\u00e0 \u0111i\u1ec7n th\u1ebf b\u1ec1 m\u1eb7t \u0111\u1ea5t<\/a><\/li>\n<li><a href=\"https:\/\/www.netaworld.org\" rel=\"nofollow noopener\" target=\"_blank\">NETA \u2014 C\u00e1c \u0111\u1eb7c t\u1ea3 ki\u1ec3m tra ch\u1ea5p nh\u1eadn (ATS) cho thi\u1ebft b\u1ecb \u0111i\u1ec7n c\u00f4ng su\u1ea5t<\/a><\/li>\n<li><a href=\"https:\/\/www.vertiv.com\/4990c7\/globalassets\/shared\/why-test-grounding-systems.pdf\" rel=\"nofollow noopener\" target=\"_blank\">Vertiv \u2014 T\u1ea1i sao ki\u1ec3m tra h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t (gi\u00e1 tr\u1ecb ti\u1ebfp \u0111\u1ea5t NEC\/IEEE 142\/80)<\/a><\/li>\n<li><a href=\"https:\/\/www.fluke.com\" rel=\"nofollow noopener\" target=\"_blank\">Fluke \u2014 Ghi ch\u00fa \u1ee9ng d\u1ee5ng ki\u1ec3m tra \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t<\/a><\/li>\n<\/ul>\n<h2>K\u1ebft lu\u1eadn<\/h2>\n<p>Hai con s\u1ed1 c\u1ee7a NEC \u2014 25 ohm v\u00e0 1-5 ohm theo h\u01b0\u1edbng d\u1eabn IEEE 142 bao ph\u1ee7 \u0111i\u1ec7n tr\u1edf \u0111\u1ea5t t\u1ed1i \u0111a cho ph\u00e9p c\u1ee7a m\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i. Trong khi NEC kh\u00f4ng xem x\u00e9t gi\u00e1 tr\u1ecb d\u01b0\u1edbi 25 ohm cho m\u1ed9t t\u00f2a nh\u00e0 th\u01b0\u01a1ng m\u1ea1i nh\u01b0 m\u1ed9t ti\u00eau chu\u1ea9n hi\u1ec7u su\u1ea5t tu\u00e2n th\u1ee7 m\u00e3, \u0111i\u1ec1u n\u00e0y ph\u1ee5 thu\u1ed9c v\u00e0o vi\u1ec7c m\u1ed9t \u0111i\u1ec7n c\u1ef1c \u0111\u01a1n c\u00f3 \u0111\u1ee7 hay kh\u00f4ng. T\u1eeb quan \u0111i\u1ec3m n\u00e0y, gi\u00e1 tr\u1ecb l\u00fd t\u01b0\u1edfng cho hi\u1ec7u su\u1ea5t \u0111\u00e1ng tin c\u1eady v\u00e0 an to\u00e0n c\u1ee7a l\u1eafp \u0111\u1eb7t th\u01b0\u01a1ng m\u1ea1i s\u1ebd n\u1eb1m trong kho\u1ea3ng 1-5 ohm, nh\u01b0 IEEE \u0111\u00e3 ghi nh\u1eadn, do \u0111\u00f3 t\u1ea1o \u0111i\u1ec1u ki\u1ec7n lo\u1ea1i b\u1ecf l\u1ed7i nhanh ch\u00f3ng, b\u1ea3o v\u1ec7 ch\u1ed1ng s\u00e9t hi\u1ec7u qu\u1ea3, m\u1ee9c \u0111\u1ed9 nhi\u1ec5u th\u1ea5p cho thi\u1ebft b\u1ecb \u0111i\u1ec7n t\u1eed th\u01b0\u01a1ng m\u1ea1i.<\/p>\n<p>S\u1eed d\u1ee5ng ph\u01b0\u01a1ng ph\u00e1p ki\u1ec3m tra r\u01a1i \u0111i\u1ec7n th\u1ebf th\u00edch h\u1ee3p \u0111\u1ec3 c\u00f3 \u0111\u01b0\u1ee3c ph\u00e9p \u0111o ch\u00ednh x\u00e1c v\u00e0 so s\u00e1nh v\u1edbi b\u1ea3ng ph\u1ea1m vi (gi\u00e1 tr\u1ecb t\u1ed1t l\u00e0 d\u01b0\u1edbi 5, gi\u00e1 tr\u1ecb t\u1eeb 5 \u0111\u1ebfn 25 l\u00e0 gi\u1edbi h\u1ea1n, gi\u00e1 tr\u1ecb tr\u00ean 25 l\u00e0 d\u01b0\u1edbi m\u1ee9c ch\u1ea5p nh\u1eadn \u0111\u01b0\u1ee3c); b\u1ea1n c\u00f3 th\u1ec3 c\u1ea7n th\u00eam nhi\u1ec1u ho\u1eb7c d\u00e0i h\u01a1n c\u00e1c \u0111i\u1ec7n c\u1ef1c v\u00e0o h\u1ec7 th\u1ed1ng ti\u1ebfp \u0111\u1ea5t tr\u1eeb khi b\u1ea1n th\u1ea5y c\u00e1c ph\u00e9p \u0111o l\u00e0 th\u1ecfa \u0111\u00e1ng. Cu\u1ed1i c\u00f9ng, \u0111\u1eebng qu\u00ean r\u1eb1ng \u0111i\u1ec7n tr\u1edf c\u1ee7a c\u00e1c \u0111i\u1ec7n c\u1ef1c ch\u1ec9 l\u00e0 m\u1ed9t n\u1eeda c\u00e2u chuy\u1ec7n v\u00e0 s\u1ef1 li\u00ean t\u1ee5c c\u1ee7a li\u00ean k\u1ebft v\u00e0 ti\u1ebfp \u0111\u1ea5t c\u0169ng ph\u1ea3i \u0111\u01b0\u1ee3c t\u00ednh \u0111\u1ebfn.<\/p>","protected":false},"excerpt":{"rendered":"<p>A person comes to perform electrical inspection in your commercial building. The engineer informs him that the ground electrode was tested at 22 Ohms. Someone nearby says that since NEC permits 25 Ohms, everything is okay. But the equipment manufacturer&#8217;s handbook states that 5 Ohm max is needed since it works with sensitive electronics; therefore, [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":3701,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_gspb_post_css":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-3700","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\/3700","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=3700"}],"version-history":[{"count":2,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/3700\/revisions"}],"predecessor-version":[{"id":3706,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/posts\/3700\/revisions\/3706"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media\/3701"}],"wp:attachment":[{"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/media?parent=3700"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/categories?post=3700"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/huyuglobal.com\/vi\/wp-json\/wp\/v2\/tags?post=3700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}