Hey all.

When I roughed in my electrical I zig-zagged my wiring for the vanity lights and just stubbed them out of a hole in the drywall at the approximate location. Now I have my exact location for the electrical boxes, but one of the boxes is directly on top of a stud.

I guess there are a few options: 1) pancake box (but I'm not sure the wires will all fit) (2) cut out the stud (3) don't use a box (is this to code?)

Any suggestions or experience with this issue? I'd like to avoid cutting unnecessary holes in the new drywall (obviously).

Thanks,

Nate

 

Option 3 is definitely NOT acceptable. Option 2 is not acceptable IF this is a load-bearing wall. It may be acceptable in a wall that only serves as a partition. Depending on the light fixture that you are planning to use the pancake box may be sufficient. Some light fixtures have an area that may be included as box volume under certain circumstances.

Next time it will help to determine exact box location and then install the boxes and wiring before installing the drywall.

 

This all depends on what your vanity light looks like. If it is the standard bar light, then option 3 might be acceptable after all.

Tell us more about the fixture.

 

The wall is an outside wall and thus not acceptable to cut out the stud I believe. The fixture is a two-bulb from Pottery Barn (mercer). The back of it has a piece that looks like it could serve as a box, but the instructions show it mounting to a typical electrical box. Here's a picture of the back (click to open larger size):



It seems that I may be able to mount this directly to the wall.

 

If that cable you land it on centre of stud you can use the pancake box to get this luminaire mounted up.

If you get the pancake box you don't have to cut the stud at all. just cut the drywall opening to match the size of pancake box and stick the new cable in and screw it on the stud and you are good to go with it.

This what it will look like




Best to use the metal verison it will hold up little better than plastic verison as you see it.

Merci,Marc

 

Ok, thanks. I've never used a pancake box. Should I pigtail everything in another box (this fixture will feed another light) or will I be able to fit everything with in this short box?

Thanks again. This is helpful confirmation.

 

Ok, tell me if I'm going about this correctly.

I have a 12/2 line, 12/load, plus 14/2 from the fixture.

If I use a metal box the connectors add one 1 conductor at 2.25 in^3.
The 2-12/2 wires yield 2*2 = 4 conductors at 2.25 in^3.
The 14/2 wire as 2 conductors at 2.0 in^3
And the ground adds 1 conductor at 2.25 in^3.

Total = (1 + 4 + 1)*2.25 + 2*2.0 = 17.5 cu in.

Now if I use a 4" pancake box, this give a volume = 4*pi*h or 12.5 * h. Thus I need a box with a height (a.k.a. depth) of 1.4" or greater.

Crap. Too many wires.

 

Use a fan box that straddles the stud and will give you more room. Let me find a link

 

Here is a link

http://www.castlewholesalers.com/RAC...ling-Fans.html

Once installed it will be 1/2" past the stud making it flush with drywall

 

Here is another link with a better pic

http://www.antonline.com/p_7120-GP_347647.htm

 

Thanks Rich. But the boxes that stradle still only have 12 cu. inches...roughly the same as 3/4 pancake and still not enough for the number of wires (or any 12/2) according to my calculations below. The way that I'm calculating it, I don't see how the pancakes can support anything but a 14/2 wire...

Nate

 

Nate,

You are correct about the pancake only being big enough for 1 14-2 cable.

Is there a way that you can reroute the wiring to cut down on the number of wires for the vanity light?

Also it sounded like you have mixed 14 and 12 gauge wiring. Is this a 20 amp circuit or a 15?

If you have 14 ga. wiring on a 20 amp circuit it should be removed or downgraded to a 15 amp breaker. If this is the required 20 amp bathroom circuit it cannot be downgraded.

 

I have 12 ga. everywhere (it's required by local code...also the 20amp circuit in the bathroom, thus necessitating the 12). The 14 is just from the fixture---typical stranded 14.

So, my solution right now is to move it over 1 inch and have it off center from my faucet. I don't think it will be that bad. I'd rather do that than pack things in a pancake and risk overheating (plus denial at final inspection).

Anyway, thanks for your help.

 

The fixture wires don't count in calculation, with 2 12-2 cables you have 5 conductors x 2.25 = 11.25


Quote from NEC

" (1) Conductor Fill. Each conductor that originates outside the box and terminates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or termination shall be counted once. Each loop or coil of unbroken conductor not less than twice the minimum length required for free conductors in 300.14 shall be counted twice. The conductor fill shall be calculated using Table 314.16(B). A conductor, no part of which leaves the box, shall not be counted.

Exception: An equipment grounding conductor or conductors or not over four fixture wires smaller than 14 AWG, or both, shall be permitted to be omitted from the calculations where they enter a box from a domed luminaire or similar canopy and terminate within that box. "


Connectors do not count unless they are internal type

Quote

" (2) Clamp Fill. Where one or more internal cable clamps, whether factory or field supplied, are present in the box, a single volume allowance in accordance with Table 314.16(B) shall be made based on the largest conductor present in the box. No allowance shall be required for a cable connector with its clamping mechanism outside the box.

 

Thomas and Betts has the CFB-12 with 12 cubic inches.


Arlington Industries has this one with 14.5 inches, FB412.