Hello. If you have two 14/2 with ground cables coming into a 3"x2"x2-1/2" electrical box with a duplex receptacle and internal clamps, is this acceptable by NEC code? All the outlets in my house are wired this way.

Here is my calculation for required electrical box volume:

8 (4 conductors)
2 (ground)
4 (receptacle)
2 (internal clamps)
-------------------
16 cu in.

The 3" electrical box with a duplex receptacle and internal clamps, is this acceptable by NEC code? All the outlets in my house are wired this way.

Here is my calculation for required electrical box volume:

8 (4 conductors)
2 (ground)
4 (receptacle)
2 (internal clamps)
-------------------
16 cu in.

The 3"x2-1/2" box would seem to have inadequate volume. Am I misinterpreting the NEC code? Can someone help me to understand? Thanks.

Just a quick look -

Regardless of the number of grounds - use 1
The duplex receptacle is "one Yoke" - use 2
Cable clamps - use I

I take a look at the code later and correct any mistakes. Just so you know, the multiplier for 14 AWG is 2.0

Hi Donf. Thanks for your reply. Those are the multipliers I used in my calculation, as follows:

(4 conductors x 2.0 cu. in. each) = 8
(grounds x 2.0 cu. in.) = 2
(1 receptacle x 4.0 cu. in) = 4
(clamps x 2.0 cu. in.) = 2

Total capacity required = 16 cu. in.

Given that the code says that a 3" x 2" x 2-1/2" box has a min capacity of 12.5 cu. in. it would seem that the boxes used in my house are under the required capacity, which is hard to believe.

4 conductors X 2.0 = 8.0
Ground X 2.0 = 2.0
1 Yoke X 2.0 = 2.0
clamp X 2.0 = 2.0

14.0

Are you sure you don't have 3" X 2" X 2 3/4"?

4 conductors X 2.0 = 8.0
Ground X 2.0 = 2.0
1 Yoke X 2.0 = 2.0
clamp X 2.0 = 2.0

14.0

Are you sure you don't have 3" X 2" X 2 3/4"?

Hi Don,
They are 2-1/2" deep. I guess it Is possible that the code requirements are different in Canada (where I reside). When you say "yoke", do you mean the receptacle? I thought the receptacle counted as 2 x 2.0 cu. in.

Hey Canada, how stands your great nation.

I believe that the box fill code would be the same. It's more likely the builder just shaved the box size by a tad, if he even thought about it at all.

If the home is an older home, I'd just leave it alone.

By the way a "Yoke" is what the receptacles mount onto.See NEC 314.16(B)(4)

Hey Canada, how stands your great nation.

I believe that the box fill code would be the same. It's more likely the builder just shaved the box size by a tad, if he even thought about it at all.

If the home is an older home, I'd just leave it alone.

By the way a "Yoke" is what the receptacles mount onto.See NEC 314.16(B)(4)

Hey Don. I appreciate your help. It doesn't sound like anything to worry about. That's the main thing. All the best. Daniel

It's really nothing to worry about. In the US they used to use crazy small boxes. Over the years the code cycles have taken this into account. This is one of the things that makes working in older homes a pain.

It's really nothing to worry about. In the US they used to use crazy small boxes. Over the years the code cycles have taken this into account. This is one of the things that makes working in older homes a pain.

Thanks stanfortyman. Daniel