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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19
votes
3answers
7k 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 ...
18
votes
3answers
4k views

Why does US Code not allow a 15A single receptacle on a 20A circuit?

Living in the UK, where we have a different system of mains wiring, my curiosity was piqued by Is it okay to install a 15A outlet on a 20A dedicated circuit for a dishwasher? and its answers. Although ...
13
votes
2answers
2k views

What range of heights are allowed for wall receptacles?

I need to mount a receptacle on a basement wall. If I can mount it high enough, it can go on the wood cripple wall instead of having to drill into the concrete and risk the excellent watertightness ...
10
votes
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?
9
votes
4answers
2k views

Why are 120 V general receptacle circuits limited to 20 A?

The NFPA-70 (National Electrical Code) prohibits the use of breakers larger than 20 A for general receptacles. But I have my doubts. A 20 A breaker on a 120 V circuit with appropriately sized wires ...
8
votes
2answers
1k views

Can I run stripped Romex/NM through conduit?

If I have NM cable running into a junction box, can I strip the sheath of the NM cable starting inside the junction box and run the conductors without a sheath through conduit that is connected to the ...
8
votes
3answers
4k views

Why aren't AFCI breakers required for bathrooms/lavatories?

Why doesn't NEC require AFCI breakers for bathrooms/lavatories? Is there a good reason NOT to install AFCI protection on a 15A/20A 120V bathroom outlet? (I.e., use GFCI only.)
8
votes
4answers
1k views

Should I keep this surge suppressor in my main load center?

I found this curious item in my main load center (circuit breaker box), marked "SQUARE D COMPANY / SECONDARY SURGE ARRESTER / J9200-10". It has been there for at least 20 years, attached to ...
8
votes
1answer
973 views

Using NEMA 14-50 with 60A breaker

An electrician installed a Tesla wall charger with a 60A breaker. I've added a NEMA 14-50 receptacle to the circuit behind a toggle switch (either the wall charger is powered or the plug, not both). ...
8
votes
1answer
21k views

Installing a new 240v receptacle - what do I need to know?

Provided I use a box large enough to meet the fill requirements (and use 10 AWG conductors), are there any additional requirements I should be aware of when installing a new 240v 30 amp receptacle for ...
8
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4answers
2k views

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 ...
7
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3answers
2k views

Any way to meet code with 40.7% or 40.44% conduit fill?

I’m running conduit along the walls in my shop (in a commercial warehouse) to provide power to some machines and additional outlets. The service is 3 phase, 208 V, 100 A. One of the machines requires ...
7
votes
4answers
2k views

How do you comply with NEC receptacle requirements in row homes with brick walls?

I'm rewiring a Philadelphia row home, which like many others, has brick and cinder block for the side walls. There is no framing, just lath and plaster. I know some flippers will put in 2x3 studs to ...
7
votes
2answers
55k views

Is there a length limit on grounding conductor to ground rod?

My service panel is over a concrete patio, it was improperly grounded in the crawlspace. I cannot drive a proper ground rod in the crawlspace so I would like to drive one into the earth on the side ...
7
votes
1answer
88 views

Main Breaker Panel in Garage w/o Garage Doors

We have a recent second floor & garage addition, and the main panel was moved to the garage from its old location. Due to COVID and our general contractor's procrastination (we have since fired ...
6
votes
5answers
7k views

Why do unfinished basements need GFCI outlets?

I was replacing outlets in the basement and noticed that unfinished basements require them to be GFCI protected. While I did do this, I can't help but wonder: WHY?? I searched for the NEC ...
6
votes
3answers
983 views

Are GFCI outlets allowed on new circuit installations?

A comment thread on GFCI outlet on 2-wire ungrounded question led to a discussion of whether GFCI is better/worse or even permitted at point-of-use (GFCI/receptacle) instead of GFCI/breakers in the ...
6
votes
1answer
281 views

Calculate electrical box volume needed

I am replacing some 15A 14/2 outlets. All went fine except the last. I think the box is not large enough. (3) 14/2 coming into the box; one is the live the other two go to other outlets All grounds ...
6
votes
1answer
176 views

Can wires go under the supply wires in my panel?

The only available knockout big enough for my #1 wires is on the right side of the panel. The new breaker (double pole 100A) needs to go on the left side of the panel. Can I cross my #1 wires under ...
5
votes
1answer
372 views

Can I paint a load center cover?

I would like to paint the cover and door of my flush mount load center to match the wall color more closely. The manufacturer does offer a white in addition to the standard grey cover, but it is hard ...
5
votes
1answer
140 views

Outlet for built-in Microwave has 120v/20A (USA) breaker… what amperage receptacle is required?

Currently I'm not able to pull the built-in microwave out to examine the outlet, so am leaning on the expertise here. It is a duplex outlet and the connected breaker is 20A, constructed around 2005. I'...
5
votes
3answers
6k views

How are equipment grounding conductors counted for determining conduit or junction box fill?

Suppose one is doing junction box fill calculations for a typical NM-B installation such as the one shown below for a switch box with one normal and one three-way switch. Which of the wires count ...
5
votes
2answers
284 views

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 ...
5
votes
1answer
616 views

Code requirement for burying electrical PVC that runs along foundation

I need to run a circuit to the opposite side of the house from the service panel to an AC disconnect box. From my understanding this could be run with THWN wire in Schedule 80 PVC above ground if it's ...
5
votes
2answers
396 views

What are the legalities associated with mounting splicing wire connectors?

There are some situations, such as those involving large junction or pull boxes that serve as central takeoff points for many-plexed homeruns or homerun banks, enclosures that form central splice ...
5
votes
1answer
23k views

Can Romex (NM-B) be run in conduit for more than 10 ft when starting from the breaker panel?

The answers to this question indicate that NM can be run in conduit: Can Romex (NM-B) be run through conduit? I was hoping to enclose 12-2 NM-B in EMT for about 20 feet from the breaker box up my ...
5
votes
1answer
243 views

Can an electrical subpanel be directly mounted to a hvac supply plenum?

Can an electrical sub panel be directly mounted to an HVAC supply plenum. I usually see and have installed the disconnect or sub panel to the actual equipment on a wall near by or used some sort of ...
5
votes
2answers
430 views

Does replacing an electrical junction box require the wiring to be brought up to code?

I live in Sparks, Nevada and the 2011 National Electrical Code applies to me. I am installing a new bathroom fan on a separate circuit from the existing bathroom circuit. I want to change the ...
4
votes
3answers
1k views

Difference between NEC code book and handbook (who is the target audience?) [closed]

My city requires electrical work to be done in accordance to the 2014 NEC. Therefore, I am purchasing the 2014 NEC. I see there are several other NEC-related books available. My question is: What ...
4
votes
3answers
2k views

Can 12 AWG THHN/THWN wire be placed in a buried conduit?

My understanding is all buried wire in conduit must be THWN-2. Per Southwire's spec sheet here the end of the first paragraph reads: All Sizes Rated Both THHN and either THWN (sizes 14, 12, and 10 ...
4
votes
3answers
4k views

Can I run #14 armored cable behind baseboards?

Residential basement remodel problem: Replacing old, ungrounded wiring. Problem is cinder block walls. Inside, the exterior walls have rigid insulation and one layer of 1 x 3 furring strips ...
4
votes
2answers
733 views

Handybox Extension

Can you stack a handybox with an extension outside of the drywall? This puts the total box size at just shy for 4". I know handyboxes can be used with conduit, but can they be double-stacked in a ...
4
votes
1answer
442 views

How is “continuous wiring” defined in context of the 2017 NEC code?

First, some context: About AFCI protection in Dwelling Units, NEC 2017: 210.12(A) All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed [...] shall be ...
4
votes
3answers
393 views

Soldering copper pigtails to aluminum wire

As I prepare to remedy my parent's 1965 home's aluminum wiring I have investigated Copalum and Alumicon. Copalum appears to be unavailable. I've tried a few Alumicon connectors but they take a lot of ...
4
votes
2answers
3k views

Ok to conceal electrical junction box under cabinet behind removable toe-kick

There is a 5 or 6 inch gap between the floor and the bottom of my kitchen cabinets. I have ikea cabinets so the toe kick is connected to the cabinet legs by plastic clips. It comes off just by pulling ...
4
votes
1answer
1k 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?
4
votes
1answer
142 views

Requirements for Surface mount raceway using THHN

At the top of a 14' wall in a private residential (non commercial) work shop, I'd like to run about 100' of surface mount raceway, with THHN conductors inside of it. I plan to use 4"x4" ...
4
votes
1answer
16k views

How many ground rods are required for panel and subpanel?

I have a main service panel with two breakers: the main service breaker and a single large breaker to another subpanel in the same structure. All other circuits are serviced from the subpanel. My ...
4
votes
1answer
2k views

NEC, use more extension boxes or an access panel?

What is the maximum number of extension boxes you can hang from a ceiling? This is ridiculous and I probably need one or two more to meet the new drywall ceiling. Are junction boxes permitted behind ...
4
votes
1answer
2k 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 ...
4
votes
2answers
125 views

Does always-on safety lighting need a switch or other requirement?

With such low-power LED lights available, I've been setting up some of my lighting to simply be on all the time, 24x7, e.g. 1 of 6 downlights or 1 out of 4 LED "tube"s in a troffer. Usually I just ...
4
votes
1answer
7k views

Do both legs in 220V have to be switched?

I posted this question but for some reason I can't get back into my account: Is it up to code to do a parallel circut with 220V? Is there a limit to number of splices? Most things I see with 220V ...
4
votes
2answers
14k views

What to do with the wires when removing baseboard heaters

I recently put in a forced-air whole house HVAC system in my old house. I'll be yanking the old electrical baseboard heaters from everywhere in the house soon. I'm wondering what all would be ...
4
votes
1answer
2k views

Conduit Underground - Ways for tunneling under obstructions?

I'm running into a situation where it's increasingly difficult to bury this PVC underground 18" in some spots due to massive tree roots. Changing directions and/or destroying the roots isn't an option....
4
votes
2answers
789 views

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 ...
4
votes
2answers
205 views

Is it legal to torque-seal terminal screws on electrical equipment?

Torque seal is a lacquer-like product used in critical applications after a screw is tightened to provide a visual indication if the screw comes loose. Considering that a terminal screw on an ...
3
votes
4answers
1k views

Does this violate electrical code? (UF run plugged into GFCI to use smart outlet)

I built a deck on the back of my house last year and installed a new breaker and a handful of outdoor electrical outlets. I wanted one outdoor outlet to be switchable via a smart outlet, but my smart ...
3
votes
2answers
513 views

Can PVC conduit be run through garage/house firewall?

The wall between my garage and the rest of my house (US) is the usual drywall-insulation-drywall wall framed out with 2x4 studs. Can I run 1.5" PVC conduit through that wall perpendicularly (e.g.,...
3
votes
2answers
837 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 ...
3
votes
2answers
7k views

Can I wire a doorbell transformer in-wall this way?

My current under-powered doorbell transformer is in a very awkward location (old home, etc.) and in a location where several old wires are cable-nutted together and I would rather not replace it there....

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