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
5k 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 ...
1
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1answer
66 views

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 ...
0
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1answer
35 views

can an indoor Transfer Switch be used on the other side of the wall as an outdoor service entrance and main panel?

Can an indoor Transfer Switch be used on the other side of the wall as an outdoor service entrance and main panel? The concept is: The outdoor service entrance is wired through the wall to the SE ...
4
votes
1answer
187 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 ...
1
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0answers
58 views

1 generator + multiple ATSes: how can I install this to Code without unobtanium?

I want to supply standby power to both units in a separately metered duplex from a single permanently installed generator. The cheapest way to do this is a pair of bog-standard ATSes and a smallish ...
0
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1answer
41 views

In conduit with 75C wire, can I use #14 wire for 20A circuits?

I note that with 8 AWG wire... in NM-B (Romex) cable I can only get 40A: I am required to pull from the 60 degree C column of Table 310.15(B)(16). However, in conduit, with 75C wire (THHN) and ...
2
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0answers
46 views

How do I connect surface wireway to a breaker box?

I am running Legrand/Wiremold 4000 series for a garage shop. The instructions for the panel connector (4086A) consist of a tiny picture that implies all I need to do is cut a large square hole in my ...
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 ...
3
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3answers
483 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 ...
1
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1answer
81 views

Oven wiring - needing to add a ground, can I retrofit?

I'm dealing with a 1970-built home and the oven has 6-3 without ground running to the oven. 2 hots and the neutral. Got a new oven coming in and want to make sure it's wired right. I could run new ...
8
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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 ...
1
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2answers
84 views

IBT and whole house transfer switch

The inter-system bonding termination (IBT) is where other services like telephone and cable TV get their ground bonds from the house's grounding electrode system (ground rods). 2014 NEC (NJ) 250.94 ...
1
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0answers
37 views

Dedicated 240v 30A Circuit Switched for A/C and NEMA 14-30 [duplicate]

I have a dedicated 240 volt circuit that's hard wired into my air conditioning unit. The circuit has a 30 amp breaker at the main box and another 30 amp breaker on the wall next to my air conditioner....
1
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1answer
38 views

Stacking 'Main lug' load centers for garage

I am aware of most NEC codes and am actually asking if this is allowed, There really shouldn't be any reason..I also fully understand keeping my netural and ground seperate and how the bus bars are ...
3
votes
1answer
224 views

What are the rules for making your own conduit KOs in nonmetallic junction boxes?

Some North American electrical boxes (usually nonmetallic ones) lack conduit knockouts, as they are designed solely to clamp NM cable. Unfortunately, some devices (the RIB series of enclosed, UL ...
1
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2answers
116 views

Why don't we just use combination AFCI/GFCI breakers for every circuit in a home?

With pretty much every circuit in a home needing one of the two types of protection (AFCI or GFCI), why don't all new homes have combination breakers installed just to be safe? Would it hurt anything ...
1
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3answers
84 views

Extremely low suspended ceilings? (NEC)

Here are the key points: Condo in NYC with concrete ceilings Recessed lighting "Exactly" The ceiling is to be dropped by only 2-1/2" The light in mind is a 1-1/4 LED light (Extremely low profile) Ex: ...
1
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2answers
68 views

Romex exiting junction box just below 8 feet

I am installing new outlets by drilling up from the garage between the wall cavity and fishing romex up. As seen in the picture: I had my first inspection and the inspector called out that the ...
0
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2answers
276 views

Running a low-voltage audio cable through a wall; with or without conduit?

I'm running wire for a 70V audio system and there is a barrier wall in the way of my run. I was wondering if it is legal as far as NFPA 70 / NEC goes if I just poke a hole in the wall (non-insulated ...
3
votes
1answer
189 views

Derating 6 current-carrying conductors?

I'm having a hard time understanding 310.15(B)(2)(a). Here's the boat I'm in: I hooking up a tankless water heater that calls for 3 40 amp breakers (it's a 24 kw Ecosmart). So I put in a sub panel in ...
0
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3answers
92 views

Is “14 AWG” NM-B allowed by the newest NEC for new residential construction?

Is "14 AWG" NM-B allowed by the newest NEC for new residential construction? My concern is what the NEC says concerning 14 AWG NM-B for new residential construction. I have been told that the "NEC ...
0
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4answers
2k views

Over-the-range Microwave on small-appliance branch circuit

Either there is conflicting information or a lack of when it comes to this question. Is it allowed in NEC code to permit an over-the-range microwave to run off of one of the small-appliance branch ...
2
votes
2answers
956 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....
1
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1answer
254 views

What does NEC require for strapping down conduit and wire here?

Below is a picture of the current conduit and wire setup for my new underground service into my house with generator automatic transfer switch and manual transfer switch to allow me to switch to an ...
1
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1answer
41 views

Do I need to upgrade other circuits if I only plan to change one?

(San Francisco, California) I plan to run a new dedicated circuit for a kitchen appliance, and to get up to code also move the bathroom to its dedicated circuit as well. This is an old house. The ...
0
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1answer
89 views

Electrical outlet clearance from a hot water panel radiator

What is the clearance of an electrical outlet from a hot water panel radiator? So facing the wall with a window and having a panel radiator down below hanged/fixed on the wall, how far away left and ...
1
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3answers
4k views

What does “No Other Outlets” mean for a kitchen 20A branch circuit?

I'm trying to wire my kitchen up to code, which means (based on the outlet spacing rules) I need 6 counter-top outlets. How many branch circuits do I need? When the NEC talks about the 2 "appliance" ...
7
votes
1answer
42k 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 ...
1
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1answer
59 views

Homeowners Electric Permit - Mongomery County, Maryland, USA [closed]

Our county allows homeowners to test to acquire permits for "rough wiring" and "heavy-ups" (https://www.montgomerycountymd.gov/DPS/Process/combuild/homeowner-electrical.html). I did electronics/...
3
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2answers
1k 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
203 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 ...
8
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4answers
755 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 ...
0
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2answers
66 views

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?
1
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2answers
1k views

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 ...
1
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1answer
46 views

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, ...
1
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2answers
72 views

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 ...
3
votes
2answers
829 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 ...
1
vote
0answers
55 views

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 ...
1
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2answers
107 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 ...
10
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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?
1
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2answers
3k views

Coast 3-way — does this conform with Code?

For those who aren't familiar, the California or Coast 3-way switching arrangement is a method of wiring a three-way switch circuit that is used when both a switched and an unswitched hot are desired ...
2
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1answer
65 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 ...
4
votes
2answers
169 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 ...
1
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1answer
57 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 (...
1
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1answer
138 views

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" ...
0
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1answer
75 views

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'...
3
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2answers
542 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 ...
0
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1answer
504 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 ...
0
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1answer
256 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 ...
1
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1answer
1k 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 ...