{"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\/tr\/blog\/maximum-resistance-recommended-for-commercial-building-electrical-installation\/","title":{"rendered":"Ticari Bina Elektrik Tesisat\u0131 i\u00e7in \u00d6nerilen Maksimum Diren\u00e7"},"content":{"rendered":"<p>Ticari binan\u0131zda elektrik muayenesi yapmak \u00fczere bir ki\u015fi gelir. M\u00fchendis, toprak elektrodunun 22 Ohm olarak test edildi\u011fini bildirir. Yak\u0131ndaki biri, NEC 25 Ohm\u2019a izin verdi\u011fi i\u00e7in her \u015feyin yolunda oldu\u011funu s\u00f6yler. Ancak ekipman \u00fcreticisinin el kitab\u0131, hassas elektroniklerle \u00e7al\u0131\u015ft\u0131\u011f\u0131 i\u00e7in maksimum 5 Ohm gerekti\u011fini belirtir; bu nedenle devreye alma m\u00fchendisi sizin i\u00e7in yeni olan bir spesifikasyona at\u0131fta bulunur. Hangi de\u011fere uyulmal\u0131d\u0131r? Sorulan soru, ticari elektrik alan\u0131nda \u00e7al\u0131\u015fanlar i\u00e7in \u00e7ok yayg\u0131nd\u0131r, ancak cevap \u00f6l\u00e7t\u00fc\u011f\u00fcn\u00fcz standarda ba\u011fl\u0131d\u0131r.<\/p>\n<p>Bu yaz\u0131, do\u011fru olan kesin say\u0131larla cevab\u0131 hemen g\u00f6sterir \u2013 hayali say\u0131lar kullan\u0131lmayacakt\u0131r. NEC\u2019in tam olarak ne istedi\u011fini, IEEE\u2019nin ne dedi\u011fini, \u201c25 Ohm kural\u0131n\u0131n nas\u0131l \u00e7al\u0131\u015ft\u0131\u011f\u0131n\u0131\u201d ve neyin g\u00fcvenli kabul edildi\u011fini \u00f6\u011freneceksiniz.<\/p>\n<blockquote><p>H\u0131zl\u0131 bir cevap ar\u0131yorsan\u0131z, t\u00fcm ticari binalarda topraklama i\u00e7in maksimum diren\u00e7 konusunda evrensel olarak ge\u00e7erli net bir say\u0131 yoktur \u00e7\u00fcnk\u00fc bu cevap hangi standarda ve sistemin hangi b\u00f6l\u00fcm\u00fcne at\u0131fta bulundu\u011funuza ba\u011fl\u0131d\u0131r. NEC (NFPA 70) bir bina i\u00e7in genel maksimum diren\u00e7 belirlemez, ancak 25 ohm kombinasyonu (asl\u0131nda 250.53\u201cte belirtilmi\u015ftir) sadece topraklama \u00e7ubu\u011fu veya plakas\u0131 i\u00e7in pratik anlam ta\u015f\u0131r ve sadece 1 \u00e7ubuk veya plakan\u0131n topraklama elektrodu i\u00e7in yeterli olup olmad\u0131\u011f\u0131n\u0131 g\u00f6rmek i\u00e7in kullan\u0131l\u0131r (yani, 1 elektrodun 25 ohm veya alt\u0131nda olmas\u0131 durumunda ikinci elektrodun kullan\u0131lmamas\u0131 uygundur). B\u00fcy\u00fck ticari ve end\u00fcstriyel sistemler i\u00e7in IEEE\u2019nin Std 142 (\u201dGreen Book\u201d), birincil topraklama elektrodunun topra\u011fa direncinin 1-5 ohm aral\u0131\u011f\u0131nda olmas\u0131 gerekti\u011fini belirtir ve sekt\u00f6r uygulamas\u0131 (NFPA\/IEEE \u00f6nerileri, NETA ATS uygulamalar\u0131, telekom end\u00fcstri standartlar\u0131 vb.) ticari binalar i\u00e7in yakla\u015f\u0131k 5 ohm ve hatta trafo merkezleri ve \u00fcretim tesisleri i\u00e7in 1 ohm hedeflemektedir. \u00d6zetle, NEC\u2019in minimum gereksinimleri, ticari binalar i\u00e7in 1-5 ohm aral\u0131\u011f\u0131nda IEEE taraf\u0131ndan talep edilen performansla ilgili de\u011fildir; bu aral\u0131k sekt\u00f6rde yayg\u0131n olarak kabul edilen hedef de\u011ferdir ve 25 ohm \u00fczeri ticari topraklama elektrodu i\u00e7in zay\u0131f ve kabul edilemez olarak g\u00f6r\u00fcl\u00fcr.<\/p><\/blockquote>\n<p>Do\u011fru olal\u0131m, \u00e7\u00fcnk\u00fc yanl\u0131\u015f bilginin kayna\u011f\u0131 buras\u0131d\u0131r. \u0130lgili say\u0131lar ve kaynaklar\u0131:<\/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=\"traget 5 ohms or less\" width=\"1448\" height=\"1086\" \/><\/p>\n<table>\n<thead>\n<tr>\n<th>Standart \/ Rehberlik<\/th>\n<th>De\u011fer<\/th>\n<th>Uyguland\u0131\u011f\u0131 Alan<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>NEC 250.53 (NFPA 70)<\/td>\n<td>25 ohm<\/td>\n<td>Tek \u00e7ubuk\/plaka elektrod \u2014 diren\u00e7 testi 25\u03a9 veya daha az ise ikinci elektrod gerekmez<\/td>\n<\/tr>\n<tr>\n<td>NEC 250.53 varsay\u0131lan<\/td>\n<td>\u0130ki elektrod<\/td>\n<td>\u00c7ubuk\/boru\/plaka elektrodlar varsay\u0131lan olarak iki adet; her ikisi tak\u0131ld\u0131\u011f\u0131nda 25\u03a9 testi gerekmez<\/td>\n<\/tr>\n<tr>\n<td>IEEE Std 142 (Ye\u015fil Kitap)<\/td>\n<td>1\u20135 ohm<\/td>\n<td>B\u00fcy\u00fck ticari\/end\u00fcstriyel sistemler i\u00e7in ana topraklama elektrodunun \u00f6nerilen toprak direnci<\/td>\n<\/tr>\n<tr>\n<td>IEEE Std 80<\/td>\n<td>5\u20131 ohm<\/td>\n<td>Trafo merkezi \/ \u00fcretim tesisi topraklama \u015febekeleri<\/td>\n<\/tr>\n<tr>\n<td>NFPA\/IEEE sekt\u00f6r rehberi<\/td>\n<td>5 ohm veya daha az<\/td>\n<td>Yayg\u0131n olarak belirtilen ticari hedef; telekom end\u00fcstri standard\u0131<\/td>\n<\/tr>\n<tr>\n<td>NETA ATS kabul testi<\/td>\n<td>5 ohm \/ 1 ohm<\/td>\n<td>\u22645\u03a9 b\u00fcy\u00fck ticari\/end\u00fcstriyel; \u22641\u03a9 \u00fcretim\/iletim istasyonlar\u0131<\/td>\n<\/tr>\n<tr>\n<td>Ekipman \u00fcreticileri<\/td>\n<td>&lt;1 ila 5 ohm<\/td>\n<td>Hassas elektronik \/ t\u0131bbi tan\u0131 ekipman\u0131 spesifikasyonlar\u0131<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>\u00d6nemli ger\u00e7ek: NEC\u2019de ticari bir topraklama i\u00e7in \u201c25 ohm veya daha az\u201d olma zorunlulu\u011fu yoktur. 25 say\u0131s\u0131 yaln\u0131zca tek bir elektrottan yeterli mesafe olup olmad\u0131\u011f\u0131n\u0131 belirlemek i\u00e7in dahil edilmi\u015ftir. IEEE 142 ve NETA \u00f6nerileri ve uygulamalar\u0131 gibi performans gereksinimleri 1 ile 5 ohm aras\u0131nda bir de\u011fer \u00f6nermektedir \u2013 en yayg\u0131n kullan\u0131lan s\u0131n\u0131r ise 5 ohmdur.<\/p>\n<h2>NEC 25-Ohm Kural\u0131 \u2014 Ger\u00e7ek Anlam\u0131<\/h2>\n<p>NEC B\u00f6l\u00fcm 250.53(A)(2) (ve ayr\u0131ca 2005 NEC B\u00f6l\u00fcm 250-56) uyar\u0131nca, kod iki topraklama elektrodu kurulmas\u0131n\u0131 gerektirir. Ancak, tek bir elektrodun 25 ohm veya daha az toprak direncini sa\u011flad\u0131\u011f\u0131 durumlarda izin verildi\u011fine dair \u00f6nemli bir istisna vard\u0131r. Ne yaz\u0131k ki, bu genellikle sadece bir elektrodun kurulup direncinin test edilmesi ve e\u011fer ilk elektrod 25 ohm direncini kar\u015f\u0131lamazsa ikinci elektrodun eklenmesi gerekti\u011fi \u015feklinde yanl\u0131\u015f yorumlanmaktad\u0131r.<\/p>\n<p>Asl\u0131nda, da\u011f\u0131l\u0131m \u015fu \u015fekildedir:<\/p>\n<ul>\n<li>Varsay\u0131lan = en az 6 feet arayla iki elektrodun kurulmas\u0131.<\/li>\n<li>\u0130zin verilen = toprak direncinin 25\u03a9 veya daha az oldu\u011funu do\u011frulayan uygun bir diren\u00e7 testine tabi tutulan tek elektrod.<\/li>\n<\/ul>\n<p>\u0130kinci elektrodun kurulmas\u0131 durumunda, kombinasyonun 25 ohm ko\u015fulunu kar\u015f\u0131lamas\u0131 gerekmez \u2014 \u00e7\u00fcnk\u00fc ikinci elektrod kurulumuyla NEC gereksinimlerini yerine getirmi\u015f say\u0131l\u0131r.<\/p>\n<h2>IEEE 142 (Ye\u015fil Kitap): 1\u20135 Ohm \u00d6nerisi<\/h2>\n<p>\u201cTicari bir yap\u0131 i\u00e7in \u00f6nerilen diren\u00e7 nedir?\u201d sorusu, IEEE Std 142 olarak bilinen Ye\u015fil Kitap\u2019tan otoriter bir m\u00fchendislik \u00e7\u00f6z\u00fcm\u00fc al\u0131r. \u00d6nerilen de\u011fer, b\u00fcy\u00fck end\u00fcstriyel ve ticari sistemlerde ana topraklama elektrodu i\u00e7in 1 ila 5 ohm aras\u0131 toprak direncidir.<\/p>\n<p>Bu diren\u00e7 de\u011ferinin 25 ohma tercih edilmesinin nedeni, ticari tesislerin genellikle hassas elektroniklerle donat\u0131lm\u0131\u015f olmas\u0131 ve bu nedenle sadece kod minimumuyla sa\u011flanamayan \u00e7ok stabil ve d\u00fc\u015f\u00fck empedansl\u0131 bir toprak referans\u0131na ihtiya\u00e7 duymas\u0131d\u0131r. Yukar\u0131da belirtilen d\u00fc\u015f\u00fck toprak direnci \u015funlar\u0131 sa\u011flar:<\/p>\n<ul>\n<li>Ar\u0131zadan kaynaklanan y\u00fcksek ak\u0131m\u0131n kayna\u011fa daha h\u0131zl\u0131 d\u00f6nmesi<\/li>\n<li>Ar\u0131za s\u0131ras\u0131nda ekipman kasas\u0131nda daha az voltaj art\u0131\u015f\u0131<\/li>\n<li>Daha iyi y\u0131ld\u0131r\u0131m dalga s\u00f6n\u00fcmlenmesi<\/li>\n<li>Daha az elektriksel g\u00fcr\u00fclt\u00fc<\/li>\n<\/ul>\n<p>\u00d6zetle, kod 25 ohm gerektirir; m\u00fchendislik terimleriyle iyi performans i\u00e7in gereken de\u011fer 1-5 ohmdur.<\/p>\n<p>&nbsp;<\/p>\n<h2>Sekt\u00f6r Uygulamas\u0131: Ticari Hedef Olarak 5 Ohm<\/h2>\n<p>Sahada, \u00e7o\u011fu ki\u015finin ticari sistemler i\u00e7in duyaca\u011f\u0131 bilgi \u201c5 ohm veya daha az\u201dd\u0131r. Bu, a\u015fa\u011f\u0131daki \u00e7e\u015fitli ancak tamamlay\u0131c\u0131 kaynaklardan gelir:<\/p>\n<ul>\n<li>NFPA ve IEEE\u2019nin 5.0 ohm veya daha az\u0131 iyi bir hedef olarak \u00f6nerileri<\/li>\n<li>Telekom\u00fcnikasyondaki yakla\u015f\u0131mlar (topraklama ve ba\u011flama i\u00e7in 5 ohm veya daha az)<\/li>\n<li>NETA\u2019n\u0131n kabul testleri standartlar\u0131 (ticari\/end\u00fcstriyel sistemler i\u00e7in \u22645 ohm; enerji santralleri\/iletim istasyonlar\u0131 i\u00e7in \u22641 ohm)<\/li>\n<li>farkl\u0131 ekipman \u00fcreticileri taraf\u0131ndan verilen rakamlar (hassas elektronikler i\u00e7in 1 ila 5 ohm aras\u0131nda)<\/li>\n<\/ul>\n<p>Farkl\u0131 m\u00fchendisler ve test uzmanlar\u0131n\u0131n ortak tavsiyesine g\u00f6re, ticari binalar i\u00e7in 5 ohm veya daha az iyidir, alt istasyonlar i\u00e7in ise ortalama de\u011fer 1 ohm ve alt\u0131d\u0131r. Bu NEC taraf\u0131ndan bir gereklilik de\u011fildir, ancak bir\u00e7ok tasar\u0131mc\u0131n\u0131n takip etti\u011fi ve testlere tabi olan en iyi uygulamalard\u0131r.<\/p>\n<h2>G\u00fcvenli Bir Aral\u0131k Var M\u0131? Say\u0131lar\u0131 Anlamak<\/h2>\n<p>Here&#8217;s how to interpret ground resistance readings in practice:<\/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=\"G\u00fcvenli Bir Aral\u0131k Var M\u0131? Say\u0131lar\u0131 Anlamak\" width=\"1448\" height=\"1086\" \/><\/p>\n<table>\n<thead>\n<tr>\n<th>Resistance<\/th>\n<th>Interpretation<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>&lt; 1 ohm<\/td>\n<td>Excellent \u2014 typical of large grids, substations, high-density electrodes<\/td>\n<\/tr>\n<tr>\n<td>1\u20135 ohm<\/td>\n<td>Good \u2014 the recommended range for commercial\/industrial (IEEE 142)<\/td>\n<\/tr>\n<tr>\n<td>5\u201310 ohms<\/td>\n<td>Acceptable for many installations, but worth improving for sensitive loads<\/td>\n<\/tr>\n<tr>\n<td>10\u201325 ohms<\/td>\n<td>Meets the NEC single-electrode threshold but marginal for commercial electronics; investigate<\/td>\n<\/tr>\n<tr>\n<td>25\u2013100 ohms<\/td>\n<td>Poor \u2014 above the NEC single-electrode limit; likely needs multiple electrodes or treatment<\/td>\n<\/tr>\n<tr>\n<td>&gt; 100 ohms<\/td>\n<td>Very poor \u2014 unacceptable for any permanent installation; rework required<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The key warning is as follows: there is not one universal &#8220;safe&#8221; value that applies to each situation from a safety perspective \u2014 it is also influenced by different factors such as earth fault current, soil conditions and the actual circuit. The quality of electrode grounding resistance is only a part of the problem; the integrity of the whole grounding system is just as important. A perfect electrode of 2 Ohm is useless if the ground conductors of the devices are crooked or corroded.<\/p>\n<h2 id=\"is-20-ohms\">Is 20 Ohms Bad? Interpreting Your Measurement<\/h2>\n<p>20-ohm resistance levels are not viewed positively in the commercial building construction code, but there are also no code violations associated with that value, hence:<\/p>\n<ul>\n<li>NEC standard: This level is less than the maximum single-electrode value determined by the above legislation. Nevertheless, 20-ohm resistance level is still close to exceeding the standards, depending on the seasonal increase and decline of moisture level in the soil.<\/li>\n<li>IEEE 142 standard: Based on this standard, the resistance level of 20 ohm exceeds the recommended value of 1-5 ohm, meaning that some of the electronic equipment, such as those preventing surge operations, might be damaged because of the improper grounding level.<\/li>\n<\/ul>\n<p>In practical terms, any commercial organization will make sure the grounding meets the set standards.<\/p>\n<p>Conclusion: Generally speaking, 20 ohm of resistance may not threaten the life of the building, but it is still too high for a commercial building; therefore, it needs to be improved.<\/p>\n<h2>Other Commercial Requirements: Receptacles &amp; Bonding<\/h2>\n<p>The ground resistance is a part of commercial electrical safety. The National Electrical Code (NEC) requirements are as follows:<\/p>\n<ul>\n<li>The characteristics of commercial receptacles (NEC 406, 210.52, 210.8): The commercial receptacles shall be specified to be 125V,15A and\/or 20A types, GFCI protection is necessary to be provided at certain locations (bathrooms, rooftops, kitchens, outdoor locations etc. per 210.8(B)), all the receptacles will be connected to the metal box and each receptacle shall be ensured to be connected to the grounding conductor.<\/li>\n<li>Bonding process (NEC 250.102-250.104): It is essential to understand that all the metallic parts which can become energized like piping, framed equipment, structural steel, pumping equipment must be bonded to the grounding system. It&#8217;s worth noting that bonding continuity testing will be carried out separately from electrode resistance (point-to-point resistance should not exceed 0.5 ohm when equipment is connected to the grounding system).<\/li>\n<li>Grounding electrode conductor (NEC 250.66): The grounding electrodes must be sized according to the service doesn&#8217;t exceed the maximum diameter and should connect the grounding system to the service equipment.<\/li>\n<\/ul>\n<p>If you&#8217;re also verifying the protective devices on the circuit, our explanation of <a href=\"https:\/\/huyuglobal.com\/tr\/blog\/circuit-breaker-and-ground-fault-circuit-interrupter\/\" rel=\"nofollow\">circuit breakers vs ground-fault circuit interrupters<\/a> clarifies which protection does what in a commercial panel.<\/p>\n<h2>What Counts as High Electrical Resistance?<\/h2>\n<p>Context plays a role in what &#8220;high resistance&#8221; means:<\/p>\n<ul>\n<li>When measuring grounding electrodes, it means greater than about 25 ohms (for instance, 100 ohms or greater is a very high value). The &#8220;ideal&#8221; resistance level is 1-5 ohms.<\/li>\n<li>In terms of continuity of grounding, anything more than 0.5 ohm indicates a fault. The connection between equipment and ground should be almost zero.<\/li>\n<li>With respect to insulation resistance, a high resistance value means a good resistance since it is measured in mega and gigohms where anything below 1 M\u03a9 indicates a high probability for a breakdown.<\/li>\n<\/ul>\n<p>In conclusion, &#8220;high resistance&#8221; almost always means a problem (for grounding) but it can mean a good situation (for insulation). Always make sure what exactly one is talking about when using a term &#8220;high resistance&#8221;.<\/p>\n<h2>Factors That Affect Ground Resistance<\/h2>\n<p>Ground resistance is not a constant value. It varies with circumstances:<\/p>\n<ul>\n<li>Soil resistivity: Clay\/loam (10\u2013100 \u03a9\u00b7m) has lower resistivity than sand\/gravel (1,000\u201310,000 \u03a9\u00b7m).<\/li>\n<li>Moisture content: Wet soils have lower resistivity while dry weather increases resistance enormously.<\/li>\n<li>Temperature: Cold soil has much higher resistivity.<\/li>\n<li>Electrode depth and cross section: Longer electrodes and bigger plates go deeper into soil.<\/li>\n<li>Number of and separation between electrodes: The more electrodes you have and the farther apart they are, the lower the resistance will be.<\/li>\n<li>Electrode material and corrosion: The longer the electrodes stay in the ground, the more corrosion there is, and resistance will increase.<\/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=\"How to Achieve a Low-Resistance Ground\" width=\"1448\" height=\"1086\" \/><\/p>\n<h2>How to Achieve a Low-Resistance Ground<\/h2>\n<p>In case your commercial grounding is excessively high, here\u2019s a ranked list of the most cost-effective solutions:<\/p>\n<ul>\n<li>Add rods: Adding a second ground rod, placed 8 feet away from the first, will greatly reduce the resistance. Continue adding additional rods until the correct resistance is achieved (the benefit generated decreases with each added rod).<\/li>\n<li>Use larger or longer rods: Using a longer rod (10-foot) or thick rods or plate electrodes will help reach deeper and less resistant soils.<\/li>\n<li>Improve soil connection: Backfilling conductive materials or chemical additives around the rod will improve its connection with the soil.<\/li>\n<li>Create ground rings or grid: Underground copper conductor encircling the structure creates a bigger area of connection (this solution is widely used in commercial\/industrial field).<\/li>\n<li>Use concrete-encased electrodes (Ufer grounds): Concrete-embedded rebar and conductor show excellent and reliable conduction properties.<\/li>\n<li>Connect to the building&#8217;s steel parts and water pipe: Connecting to the metal structural steel and underground water pipes (if any) gives additional ways of conduction.<\/li>\n<\/ul>\n<p>Be sure to test every time you change the system, but keep in mind that the NEC does not require retesting the two-electrode system.<\/p>\n<h2>How Ground Resistance Is Tested<\/h2>\n<p>Ground testing is to be carried out by persons qualified for this job. The main and widespread methods are:<\/p>\n<ul>\n<li>Fall-of-Potential (more commonly known as three-point testing): The fall-of-potential method consists in the use of two temporary stakes and resistance measuring with increasing distance. It is the most precise technique used for small to medium installations.<\/li>\n<li>Clamp-on (or inductive) testing: The clamp-on method involves the clamp around the rod\/conductor so that the loop resistance can be measured without disconnecting the loop. It is advantageous for the already existing installations but requires the whole loop connected.<\/li>\n<li>Two-point testing: The two-point method is used to make fast measurements against a known reference electrode: this technique is less accurate, thus used in rough calculations.<\/li>\n<\/ul>\n<p>Testing is dangerous, since it usually requires isolation of the electrode, and fault current may be present, this job should not be done by an ordinary homeowner. For commercial buildings the commissioning and regular tests usually are performed by contractors or specialized companies in accordance with NETA standards.<\/p>\n<h2>S\u0131k\u00e7a Sorulan Sorular<\/h2>\n<h3>Which guideline outlines the acceptable maximum resistance for earthing in commercial installations?<\/h3>\n<p>NEC does not specify a single standard maximum value. The 25-ohm requirement outlined in NEC 250.53 applies only to the case of a single-electrode system, and not to the whole building. A major engineering standard is IEEE Std 142 (the Green Book), which suggests that the value of the main grounding electrode in large commercial and industrial installations should be in the range of 1-5 ohms. Normally, in practice, and accepting standards set by NETA, the value of 5 ohms is satisfactory for a commercial building (1 ohm for a substation). In general, NEC shows the limit according to the requirements of the code, IEEE 142 provides the acceptable range according to the engineering requirements, and then 5 ohms emerges as the accepted practice.<\/p>\n<h3>Is 20 ohms of resistance in a ground bad?<\/h3>\n<p>A resistance of 20 ohms is not hazardous in itself but is borderline acceptable for commercial buildings. While the NEC&#8217;s single-rod criterion of 25 ohms is passed, the number is above the level recommended by IEEE 142 for commercial installations, which is 1\uff0d5 ohms, as well as the commonly accepted level of 5 ohms. With that level of grounding, the fault current is returning in a slower manner and not providing remarkable surge protection or reference grounding for sensitive electronics as well. And since it is just a step away from going above the code threshold, the level may go up as a result of soil condition changes during the seasons. Hence, the grounding system should be improved in the case of commercial installations.<\/p>\n<h3>What are the NEC commercial receptacle requirements?<\/h3>\n<p>All commercial receptacles have a voltage rating of 125 volts to 15 or 20 amps as stated in NEC 406, and their minimum amount and spacing rules can be found in 210.52 for general areas. GFCI protection is mandatory in given commercial spaces under NEC 210.8(b), such as bathrooms, kitchens, rooftops, outdoors, and garages\/service areas. All receptacles must be provided with an equipment grounding, and metallic boxes are to be grounded. In many commercial child-occupied places, tamper-resistant receptacles are a must, while some types of occupancies have their particular rules for provided receptacles.<\/p>\n<h3>What is a high electrical resistance?<\/h3>\n<p>&#8220;High electrical resistance&#8221; depends upon what measurement is at hand. With regard to grounding electrodes, anything over approximately 25 ohms counts as high, while numbers over 100 ohms are considered very high. Ideally, the resistance should be somewhere between 1 and 5 ohms. Concerning equipment grounding continuity, the electrical resistance should not exceed 0.5 ohm when measuring the equipment and the ground. In insulation, a high resistance is a positive sign. For insulation to be considered healthy, it must have a resistance of millions of ohms (M\u03a9) or even billions of ohms. A resistance level of less than 1 M\u03a9 indicates a breakdown with leakage danger.<\/p>\n<h2>Referanslar<\/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), Article 250 (Grounding &amp; Bonding), 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 Recommended Practice for Grounding of Industrial and Commercial Power Systems (Green Book)<\/a><\/li>\n<li><a href=\"https:\/\/standards.ieee.org\/ieee\/81\/4395\/\" rel=\"nofollow noopener\" target=\"_blank\">IEEE Std 81 \u2014 Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials<\/a><\/li>\n<li><a href=\"https:\/\/www.netaworld.org\" rel=\"nofollow noopener\" target=\"_blank\">NETA \u2014 Acceptance Testing Specifications (ATS) for electrical power equipment<\/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 Why Test Grounding Systems (NEC\/IEEE 142\/80 grounding values)<\/a><\/li>\n<li><a href=\"https:\/\/www.fluke.com\" rel=\"nofollow noopener\" target=\"_blank\">Fluke \u2014 Ground resistance testing application notes<\/a><\/li>\n<\/ul>\n<h2>Sonu\u00e7<\/h2>\n<p>The NEC&#8217;s two figures \u2014 25 ohms and 1-5 ohms as per the IEEE 142 guide cover the maximum allowed electrical ground resistance of a commercial building. While the NEC does not consider for a commercial building the value of under 25 ohms that would indicate compliance with the code as a performance standard, it depends on whether a single electrode is sufficient. From this standpoint, the ideal value for reliable and safe performance of commercial installation would be in the range of 1-5 ohms, as noted by IEEE, thus facilitating fast failure elimination, effective surge protection, low noise level for commercial electronics.<\/p>\n<p>Use proper fall-of-potential testing to get a good measurement and tally it against the range table (as good value is under 5, value ranging from 5 to 25 is marginal, value over 25 is below the acceptable level); you may need to add more or longer electrodes to the grounding system unless you find the readings satisfactory. Finally, do not forget that the resistance of electrodes is only half of the story and the continuity of bonding and grounding must also be accounted for.<\/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\/tr\/wp-json\/wp\/v2\/posts\/3700","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/comments?post=3700"}],"version-history":[{"count":2,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/posts\/3700\/revisions"}],"predecessor-version":[{"id":3706,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/posts\/3700\/revisions\/3706"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/media\/3701"}],"wp:attachment":[{"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/media?parent=3700"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/categories?post=3700"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/huyuglobal.com\/tr\/wp-json\/wp\/v2\/tags?post=3700"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}