Hot answers tagged

10

Why 20A? Receptacle design constraints, most likely The reason why general receptacle circuits top out at 20A is because the notion of a duplex receptacle doesn't work for larger plug sizes (just can't fit enough meat in there at a suitable spacing for it to work), nor does the idea of a "shared" receptacle (T-slot) that can accept 15A or 20A plugs, as well ...


10

Derailed by Derating Your plan is a non-starter, even if you overcome the fill issues you're having, because of the other limit the NEC places on conduit fill; namely, the derating factors found in 310.15(B)(3)(a) that limit ampacity based on the number of current-carrying conductors. The first two rows of the table are normally not an issue because nobody ...


8

Too many circuits per pipe All this is about the derating rules in 310.15(B)(3)(a), see ThreePhaseEel's answer. When I first saw your other question, I thought "Oh boy, I smell a too-many-circuits problem coming". I thought I should warn you to run multiple conduit, but I didn't mention it because it was out of scope. Now, if you were strictly working ...


7

The supply circuit breaker has to protect not just the cables in the wall, but also the flexible cords to the appliances. If you had 50A circuit breakers, the appliance cords would have to be rated to carry the higher fault current in the event of a short-circuit. The fault current would be several times 50A, but usually for a short time, depending on the ...


6

NEC 300.4(D) covers the type of installation indicated in the question, and it applies to both AC and MC armored cable. So you'll need to use a steel guard at least 1/16" thick to protect the cable. This tip from Fine Homebuilding illustrates this type of installation. Rather than backing the molding with steel plating, they use a U-shaped channel to ...


6

You need a 12/3+ground cable as a minimum to support this oven. However it would be a nice future-proofing trick to run 10/3+ground. You can also run individual wires in conduit if you prefer, for the ultimate future-proofing. I would run 3/4" conduit, or 1" if able, as that will support any foreseeable future oven/range. You must run neutral and ground ...


6

Yes, that's fine anywhere the aesthetics are acceptable, but please don't. I'd much rather see you install either a 4 x 4 x 2-1/8 junction box, or a 4-11/16" square junction box, and fit a 1-gang mud ring. If it's a Decora device, use a mud ring with at least 1/4" of bump. Otherwise they make flat plates with 0" bump. You can also use one with a domed ...


5

It does violate the NEC (assuming that you are in the US and the NEC applies to you). UF cable is not designed to connect to portable cord devices, portable cord devices are not designed to accept UF cable. Article 110.3(B) states: "Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling....


5

That is fine. NEC is silent on the issue, except for 110.3B, which defers to the unit's labeling and instructions, which is NEC's way of deferring to UL (or other NRTL; CE is not one). UL Approves the panel based on the labeling and instructions. However, if the panel is CH, the panel color is already perfection. So paint the rest of the house to match the ...


5

It will be ugly, but I am aware of no code rule that would stop you from using an extension on a surface mounted handy box. However I can't imagine why you would; it would be just as easy to switch to say a 4x4 box with a raised industrial cover, plenty of room inside, and it would protrude less, and it wouldn't be so ugly. As mentioned in @Harper'...


4

I suspect it comes from long experience, and that it's all about current, not voltage. Why? Because despite being isolated when these standards were set, everyone reached the same conclusion - UK, Germany, Greece, Russia, Soviet Union, Italy, Spain, etc. I believe that's because of the relationship between breaker trip and the potential fire damage an arc-...


4

Yes, the NEC. Is free once adopted . search for free NEC and you will find it. This is only for the "code" I don't think they release the hand book that has a lot of information on why, this is the version most inspectors use , but once adopted the NEC is free on line. Just checked look up nfpa.org free access just need to sign in.. Free Access to NEC


4

I agree, this is "nope". The way I would handle this - first, I'd use metal boxes because I'm lazy about running ground wires. I'd start by removing the current box. I'd knock out the highest 1/2" or 3/4" knockout and fit an EMT spacer to connect to a 4-11/16" square steel box. We'll need the room. Fit a steel cover that provides 2 Decora. One slot ...


4

+1 for @ThreePhaseEel. If you do not have any other option but to run 1" EMT then the only other way I can think of to satisfy loading your conductors is to run 1 set of #4 THHN, THWN or THWN-2 copper conductors, which have a capacity of 85A. Then you can set a subpanel at the equipment location and feed individual pieces separately. Of course you will ...


3

The line voltage parts of the circuit must be contained inside an electrical box which has an accessible cover. The low voltage wires should not be inside the electrical box. If I were doing this I would make a new opening for an old work electrical box up near the ceiling of the closet. Then drop a new electrical cable down the stud cavity from the new ...


3

2014 NEC Article 352.30(A) states that PVC conduit should be supported within 3' of each outlet box, disconnect, panel, etc. That also Includes strapping the 90% ells you have installed. I can see that you have installed expansion joints so the strap has to go above the joint to allow the joint to expand with the grade. Also the ground wire is attached ...


3

The ultimate arbiter is your AHJ. Don't be afraid to ask. My experience in the area (less City proper, more peninsula) is that you won't have to change untouched circuits.


3

There is nothing in the NEC that forbids 15A circuits with 14AWG wire in new work There is nothing in the NEC (2014 or 2017) that forbids the use of 15A circuits wired with 14AWG NM-B for general lighting and receptacles (irrespective of occupancy). Some localities do amend the Code to require the use of 20A branch circuits (with 12AWG wire, of course) for ...


3

You need a conduit. For that matter you would need a conduit if running them inside the ceiling space.


3

I'd scrap this whole plan and start over (save for the existing buried conduit) You started off on the right foot by burying a conduit from the house to the shed, and you are also correct that NM is nogoodnik in a wet environment, so we'll be replacing that as you indicate. However, you were only familiar with the cables (NM and UF) used for building ...


3

There is no requirement for GFCI receptacles anywhere. GFCI protection is what is required. That can be in many locations - a breaker, switch, deadfront or indeed a receptacle. Further, each can protect downline locations so they too are GFCI protected. Having more than one GFCI per breaker trip circuit indicates someone doesn't understand this ...


2

210.52 (B)(1) says that the 20A circuits shal serve all wall and floor receptacle outlets covered by 210.52(A), all countertop outlets covered by 210.52(C), and receptacle outlets for refrigeration equipment. 210.52(B)(2) Says that the two or more small-appliance branch circuits specified in 210.52(B)(1) shall have no other outlets. 210.52(A) - General ...


2

I actually agree with someone in the comments. Running wires to a location and leaving them "live, but connected to nothing" is inappropriate. It would never be allowed in conduit; you are expected to either pull useless wires or put them to a use. In cable-in-wall construction, it is allowed to set unused cables due to the impracticability of accessing ...


2

Sure, go for it There's no basic problem with what you propose. Feel free to put CAFCIs in all breaker positions. You may have a problem finding AFCIs larger than 20/30 amps, and you may have trouble finding 2-pole AFCIs in some cases. In this instance, for equivalent protection where AFCI is not mandated, simply run those circuits in metal conduit, e....


2

Easy. Cut up bits of 1x4 so you can fit them on the wall around the cable, so the cable goes between them. Then cap it off with another scrap of 1x4. The one-by dimension is ample to provide clearance for the cable.


2

Since the plug connection is on the low voltage side I would say it is code compliant by the NEC. The Code does prohibit plug connections above drop ceilings but that is for the high voltage side of this light or 120v plugs. The low voltage side would fall under a different part of the code. These lights are becoming quite popular and I wouldn’t figure ...


2

NEC doesn't care how tall your drop ceiling space is. Bender might. The only thing I can think electrically is that you're not allowed to use cord-and-plug connections above a drop ceiling, (400.7 and 400.8), unless your locality gives you a waiver. But I don't gather you plan to, since the box + receptacle + plug combination would be taller than your ...


2

With concrete ceilings/floors between levels, you can install any rated or unrated suspended ceiling. (The concrete ceiling/floor assembly provides the necessary fire rating between floors and between units.) However, there are height restrictions (which you didn’t ask about).


2

You can retrofit just ground. Really. The biggest misconception is that you must replace all the wires. Nope! NEC has allowed you to retrofit grounds on feeders and larger circuits for awhile, and it worked so well that in NEC 2014 they threw it open to all circuits. This is an exception because ground is special. Normally, it's a fixed rule that ...


2

While you are correct that a few milliamps can kill, circuit breakers are about protecting the wire and home from fires, not about protecting against electric shock. That's the job for a GFCI system if it's required by code for the application. A "standard" residential receptacle is rated for either 15A or 20A. For higher capacity circuits, you must use a ...


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