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33

When or is it NEC code compliant to upgrade a 2-wire circuit, by adding a third prong equipment ground from a nearby galvanized cold water pipe? Never! Article 250.118 of the National Electrical Code lists the approved methods of equipment grounding. Water piping systems are NOT listed there. Metal piping systems within buildings are required to be bonded ...


17

There is one safety issue here It appears that the original installer took the ground wire from the 12/3 cable, looped it around one switch ground screw, then attached it to the other switch ground screw. This grounds the switch yokes fine, but leaves the (metal) box ungrounded save through screw threads. The solution to this is to cut off the existing ...


10

Enclosure You start with an enclosure that includes a backplate (interior panel) -- usually this is purchased separately from the enclosure itself, but the manufacturers make sizes that fit mounting holes in their enclosure. Enclosures come in many sizes, different materials, different NEMA ratings, different cover options (screw-on/hinged, handles, ...


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 ...


9

It's mandatory When putting identical-appearing circuits in a conduit, you must differentiate them somehow. It's mandatory. I would not bundle them but mark them individually. Black(blue) and White(blue) for instance being the obvious pair. Bonus points: use a decent length (2") of shrinkwrap so the tape doesn't come off someday. The reason I don't ...


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

Be sure you use a 30A double-pole breaker to adequately protect your wiring. Make sure you provide an equipment ground and use a NEMA 14-30 receptacle. The box can be metal or plastic. Some form of cable clamp is always required, it's just that most plastic boxes have an integrated clamp (that finger-trap style door). If using NM cable, The cable must be ...


7

This answer is mostly based on the United States electrical system, and the answer may vary depending on where you are. The NEC code specifies that a solid copper wire used to connect to a ground rod must be at least either #6 or #8 gauge (depending on the size of your electrical service cable). #6 cable cable will always satisfy the sizing requirement, ...


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

The NEC simply states "where supplied through a ground-fault circuit interrupter" in this instance, so you can achieve this either by a GFI receptacle, a faceless GFI device, or a GFI breaker. You cannot however use an AFCI breaker, unless it is one of the new (and rare) AFCI/GFCI breakers. Good luck finding one though. I find one Siemens on Amazon and that'...


6

You can run cables across and under the joists. If you do though you must install them on running boards for protection. Typically it is just easier to drill. National Electrical Code 2011 Chapter 3 Wiring Methods and Materials Article 334 Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS II. Installation 334.15 Exposed Work. (C) ...


6

Simply twisting is not enough. You need a mechanical connection as well. Wire nut, crimp, etc. NEC 110.14 Electrical Connections Because of different characteristics of dissimilar metals, devices such as pressure terminal or pressure splicing connectors and soldering lugs shall be identified for the material of the conductor and shall be ...


6

Don't mix up your EGCs and your GECs! The EMT, provided it is made up properly and is not excessively exposed to physical damage, is a perfectly fine ground (equipment grounding conductor) by itself in this application -- 440.9 in the 2017 NEC only applies to runs on roofs, which get tread on repeatedly by clueless folks: 440.9 Grounding and Bonding. ...


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 ...


5

There is no limit on SIZE - I've worked (in non-residential settings) with some you could sit in. The practical concern with the "box and 4 extensions" shown is that the wires up at the ceiling are supposed to be able to come 6" out of the open face of the box, IIRC. From a practical working point of view it's usually better to put in a large box you can ...


5

The definition of readily accessible in the National Electrical Code. Accessible, Readily (Readily Accessible). Capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to actions such as to use tools, to climb over or remove obstacles, or to resort to portable ladders, and so forth ...


5

In the US under the NEC in a residential setting there is no prohibition for a 15A general use receptacle circuit. You are correct in that some areas; kitchens (and similar/associated rooms), laundry, bathrooms, do require 20A receptacle circuits, but there is nothing that prohibits 15A receptacle circuits in most other places.


5

The National Electrical Code requires GFCI protection in some locations, it does not specify how that protection is provided (well... It gives you options on how you can do it). If GFCI protection is provided by a breaker, then the GFCI protection requirement is met.


5

I would consider this a hallway and hallways less than 10' do not require an outlet NEC 210.52.H. This is not a room as defined by 210.52.A. The commentary for 210.52.a.3 says: any wall space that is unbroken along the floor line by doors, fireplaces, archways and similar openings must be included in the measurement. Room dividers such as bar type ...


5

The 'Yoke' is the structural frame of a receptacle or switch: It is often metal, with holes for two captive mounting screws, and should almost certainly be grounded if a grounding conductor is present. Examples: A light switch in a single-gang junction box has a single yoke. Receptacles (in North America) are often manufactured in a pair of two outlets on ...


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 ...


4

Please see this answer, for more detail. Basically if you have equipment grounding conductors enter the box, you add 1 fill unit. Example Breakdown In the example you've provided you have 12 if it's a box without internal clamps, and 13 if it has internal clamps. Current Carrying Conductors Ungrounded (hot) 4 Grounded (neutral) ...


4

Do not connect the sub panel to grounding electrodes. A grounding conductor must be run back to the main service panel. The main service panel is the only connection to a grounding electrode system in a single building without a separate means such as a genset. The underground metal pipe could be used as an electrode, but it sounds distant. So you should ...


4

The required lighting outlet for areas with equipment is definitely not required to be on a dedicated circuit. It can be on any general circuit. Same goes for the receptacle. It is not required to be dedicated, but typically this is. This receptacle is required for unfinished basement areas. It's not required to be at the panel, but usually this is the ...


4

There is no NEC restriction to keep indoor and outdoor lighting and receptacles separate. I've never even heard this mentioned before. It's not a bad idea to keep receptacles separate, even for the reason you mentioned, but lighting is no problem to combine. Just keep an eye on the intended use loads so that you will not have a circuit loaded to heavily.


4

Building codes (including the NEC and many others covering a variety of subjects) are usually written by independent organizations who specialize in the subject. Local laws are passed by governments. Since local politicians are generally not electricians / structural engineers / fire marshals etc, they "adopt" the 3rd party codes by requiring all local ...


4

Answer based on the NEC in the US: Can I install a receptacle a few inches in on the half-height wall (so that it's still under the counter, but not a full 12" in)? Yes, that's almost right. As long as you are not more than 6" in laterally off the counter edge you are fine. Also, the receptacle cannot be more than 12" down from the counter top.


4

You may be thinking of GFCI, whose purpose is to protect humans from shocks, and is mostly relevant on receptacles. The purpose of AFCI is to protect structures from bad wiring by tripping when wires arc from a bad connection. That is relevant anywhere there is wiring. In fact, it's a pretty good substitute for rewiring buildings with problem wiring, ...


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