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Questions tagged [nec]

For questions about the National Electrical Code, NFPA 70. Just about all US jurisdictions that have adopted an electrical code use the NEC, often with a handful of local or state level amendments.

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NEC (United States)

Is there a website where I can access the complete and most recently updated version of the United States NEC for free?
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Can I add USB outlets to bath/hall lighting circuit box (not GFCI)?

My bathroom, inside near door, has a 2-gang box, containing 2 light switches, powering combination ceiling light and fan. This box is fed by hallway lighting circuit, and the work box is not covered ...
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Main Breaker Panel or Main Lug Panel for Sub-panel in Attached-Detached Garage

I am installing a ~100-amp sub-panel in my "attached-detached" garage (an "attached-detached" garage is a detached garage that shares a continuous roof with the home). The sub-panel will be fed by my ...
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Intersystem grounding bus ran out of terminals; now what?

My intersystem grounding terminal bus is out of available terminals, and I have two additional communication wires to ground to it. Does NEC allow supplementary bus bars? NEC 250.94 seems to imply no, ...
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Operational Electrical Panel in an unfinished building — safe? Sane? Legal?

Is it realistic to have an operational and functioning load center panel (with power supplied only to temporary outlets mounted near the panel), fed by an offgrid solar system, in a half-built ...
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813 views

Is it OK to have a light that can only be controlled via automation?

I am retrofitting the main light in a room to be controlled by a home automation system, in this case, I'm using z-wave, but for purposes of this question, it could be any digital protocol. I would ...
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Approved weatherproof way of connecting SER into panel

I have a knockout in an outdoor electrical panel that is above the uninsulated portion of the panel. I need to run 4/0 SER wire into the panel. According to NEC 312.2, I need a wet listed fitting when ...
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48 views

THHN to NM-B wiring, Transition from External Piping Conduit to in wall junction box

I am working on a project, In my own home, Permanently installing a Faux Fireplace, Shiplap, and some iron pipe shelves. The shelves are going to have built in lighting in the form of Edision Bulbs at ...
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1answer
5k views

Is this wiring safe and is it according to code?

A single 12-3 cable was run to a double switch to control individual lights. The white is used as a hot, is this wiring correct/per NEC code?
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1answer
47 views

2 meters for 1 structure

We are currently building an addition to our house. It was a duplex before (one part stick built, other part mobile home, they were connected by a common entryway). We moved the mobile home away and ...
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56 views

Can a single cable type do the following

Running from a new 200amp main interior in the attached garage, out a 150 amp breaker into 4/0 cable (4/0-4/0-4/0-2/0 assumed). The cable will travel about 30 feet inside through raceways and EMT (...
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are tamper resistant receptacles required when rewiring an old house

rewiring an old house due to having knob and tube wiring. it it code to have all receptacles tamper resistant? Does the NEC require hard wired smoke and carbon monoxide detectors? Are "in-use" ...
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is AFCI required for 220v CA residential?

As I understand it CA now requires AFCI protection for practically all residential outlets. I'm setting up my theater room and it calls for a 50A 220V NEMA 6-50 outlet for the subwoofer I want but I'...
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246 views

Relabeling 6-AWG Wire

I'm pulling 2 hots, 1 neutral and 1 ground through conduit to a subpanel and I was wondering if it's possible to use the same color wire and just relabel the endings. I was thinking of using 6 AWG ...
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60 views

PVC conduit into PVC box: Can I make it watertight when using a threaded fitting? Are sealing locknuts allowed?

I have some 2" PVC conduit coming out of the ground and into a PVC box where it enters with a terminal adapter and held in place with a locknut. I intended to use a sealing locknut to keep the box ...
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1answer
106 views

is there an outlet box mounted overcurrent protection device?

I am adding some additional outlets and outside lights to my garage. The existing outlets are on 12 gauge wiring, so presumably a 20 amp circuit (I did not check this - did not have my reading ...
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3answers
834 views

Can I add a non-GFCI receptacle in the garage for a freezer?

It seems that GFCI-protected receptacles are required in all areas of the garage (even on the ceiling, where the garage door opener plugs in). Can I install a non-protected (15A) receptacle ...
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How should ground wires be handled when updating switch loops in an older home?

I have a house built in the 1950’s with fabric covered NMC wiring still present in most circuits. Those original wires are all 12/2 with no ground. I am currently in the process of replacing some of ...
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Questions regarding my plan for new 50A circuit (with pictures)

Overview Pictures/diagrams at the end. I will pull permits and would like to do this correctly. I will be disconnecting an unused 40A circuit and replacing it with a new 50A circuit to my garage for ...
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Is NEC code for non-metallic cable applicable now that I've installed an attic ladder?

Just installed an attic ladder. I've read this: What is the proper 'per code' method for running nonmetallic sheathed cable above a ceiling in the attic? So my attic is now "accessible" and ...
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3answers
4k views

How to connect grounding wire to gas pipe for 2017 NEC 250.104(B)

I'm trying to interpret and apply the 2017 NEC bonding requirements from 250.104(B) to my existing home gas line. I've read this related question to determine I should use #6 AWG wire, but I'm unsure ...
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Is a Garage considered a 'Dwelling' for standalone electric service?

I just wrapped up adding new overhead 100 amp service for my parent's garage outside Chicago. My Mom is a retired ceramics teacher and wanted a 30A two phase kiln and/or welder in there and the ...
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Move grounds to subpanel when I moved 8 single pole breakers to same subpanel?

When I move 8 breakers from main panel to a subpanel (a few feet away) can I simply move the hot and neutral only to subpanel? The 8 breakers are grounded in the main panel already. A 100 amp breaker ...
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Can I use a ground rod as an equipment ground for a detached garage?

I'm in a bit of a dilemma. The house we bought has a detached garage supplied by 12/3 UF with ground. The previous owner/handyman set this up as a multiwire branch circuit (MWBC) with a twist: one ...
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1answer
438 views

interpretation of conduit vs raceway wet location vs outdoor vs NM NM-B

eventual question: for a sealed PVC conduit external to house, does that qualify as a wet or damp location preventing use of non metallic (NM or NM-B) indoor type wire? And does underground feeder (...
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893 views

OK to bundle wires together with colored electrical tape?

I have 3 bundles of 3 12AWG THHN wires each, black-white-green (red tape) black-white-green (blue tape) black-white-green (black tape) these 3 bundles come out of the load center and into 1/2 EMT. ...
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1answer
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What is a 'Yoke' in NEC / electrician parlance?

NEC rules sometimes refer to "the yoke". For example: 1999 NEC § 210-4(b): Dwelling Units. In dwelling units, a multiwire branch circuit supplying more than one device or equipment on the same ...
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What NEC code limits circuit breaker selection?

I'm looking for a citation of the section of code that states more or less "You may only use breakers in a breaker panel that said panel lists as approved for use therein.". What is the section ...
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652 views

does the NEC allow conduit attached to my house to an outbuilding or does it have to be buried?

I have a shed im running electrical to, which is detached. the subpanel in the shed is being powered by a 40amp double pole from the main service with THHN/THWN 8 gauge wire. I am going to attach ...
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1answer
4k views

Is it OK to create a third prong ground from a cold water pipe, for a 2-wire circuit?

When or is it NEC code compliant to upgrade a 2-wire circuit, by adding a third prong equipment ground from a nearby cold water pipe? A different case of borrowing a ground from a nearby circuit is ...
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1answer
321 views

Splitting off one leg of a 20A 220v circuit for a plug - Is this to code?

I want to avoid buying another breaker and using a slot up in my sub panel just for one plug. I bought a plug\box kit which contains a 15A receptacle. I assume this wouldn't be to code since the ...
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106 views

Several Electrical Mains into a Single Panel [closed]

For an existing building, seven single-phase mains supplies with meter devices installed by the electrical company are supplying electricity into a same tenant installation. The tenant receives a ...
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Would it be reasonable and legal to use AFCI receptacles next to a panel instead of AFCI breakers?

I've been googling, searching this community and looking over the 2017 NEC codebook (which can be very confusing) and I've come to the conclusion that a crystal clear, no nonsense, straight forward ...
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How do I qualify for the 75C table in the ampacity chart?

Suppose we direct-buried some 8 AWG cable. It's now under a parking lot, and retrenching it is out of the question. Now, needs have changed and we need to get 50A out of the circuit, which is ...
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48 views

FMC run for GFCI receptacle?

I have a water heater room 5x8 that needs a GFCI receptacle added to the ceiling for a hot water recirculating pump. The heater is large and obviously hard plumbed in so cannot be moved and rigid ...
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Switchable 50A outlets for arc welder

I'm hoping to run two 240 V 50 A outlets for an ARC welder. One will be outside and the other inside the shop. If I install a double pole double throw switch such that only one receptacle can be ...
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BX to NM-B using GFCI and AFCI in line

Is it okay (to code and safe) to attach BX to a GFCI, then from the GFCI, non-metallic sheathed cable (NM-B) to an AFCI and then add outlets down stream from this? I am updating a room in my house ...
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1answer
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NEC code requirements for exterior outlet

Are there any code requirements with regard to the position of an electrical receptacle on an exterior wall? Such as distance above the ground, distance from a corner, distance down from a roof ...
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1answer
387 views

Are there any NEC restrictions for wiring 220v and 110v sockets on the same dual pole breaker?

I am working on an electrical upgrade for my garage. Some equipment I have requires 20A 220V power. Other equipment only needs 15A or 20A 110V. I would like to run in from a single circuit protected ...
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1answer
713 views

Do NEC receptacle spacing rules apply to solid (half-wall) banisters

I have a solid banister over my stairs. If it counts as a wall per NEC, then it needs an outlet. I can't find the reference in NEC defining a wall. Anybody know if this counts?
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559 views

Use 60Amp disconnect as a pass-through to another disconnect

We would like to add a second air-conditioning unit. The original 60 Amp disconnect is grounded via EMT to the panel. The existing EMT will meet code requirements for both conduit fill and derating ...
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2answers
716 views

NEC code regarding grounding and conductor pass through

I am adding a mini split system to my house which currently has a smaller air-conditioning condenser in place. In brief, the house is very old so we opted for a ductless mini-split over trying to ...
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91 views

How should a GFCI be installed according to the NEC?

I am taking a National Electric Code safety class as part of an electrical maintenance certificate course. On one of my quizzes, it asks me to explain how a GFCI is to be installed and tested. I've ...
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1answer
484 views

Is there any way to do an Ufer (concrete-encased) ground with a monolithic slab that has a vapor barrier?

If I understand correctly, when using a monolithic slab (where the footers and slab are poured as one piece), the vapor barrier is installed under the slab and the footers. The NEC does not consider ...
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2answers
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How is the minimum conductor size (of some type) for a certain run determined?

I have a 200A service in a garage. I would like to run cable from this to a 100A service in a house. I would also like to run from this to a separate 50A service in the house which will supply ...
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89 views

BX cable in plaster by sink

I am re-plastering a wall in my kitchen after removing some damaged plaster. I am burying the electrical in BX cabling before plastering as allowed by NEC. However, NEC does say BX is not allowed in ...
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179 views

Does the lighting fixture size change the number of allowed wires in a junction box?

In am working on a 1920s era home. The electrical system in the house has been updated several times in a very hodge-podge way. Originally the house had conduit in the attic going from light ...
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1answer
186 views

Does the NEC permit brazing for connections to ground electrodes?

I need to connect several copper-clad ground rods together with AWG 6 solid copper wire for lightning protection, and as part of the electrical service grounding. I also need to connect some 2.5" ...
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139 views

How can we move a subpanel without replacing the supply cable?

We recently installed a subpanel, installed it ourselves and had it inspected. Now, as part of the ongoing renovation of the house, we have decided we need to move the panel over 22 inches. The 6 awg ...
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3answers
271 views

Properly installing a grounded subpanel for lightning protection

I'm installing a large antenna on the side of my house opposite the electrical service entrance. The antenna must be grounded, by nature of its design. For lightning protection, it's important that ...