Back box size

[m sleem]

In order to run two 3/4" conduits in/out from 2"x4" back box of duplex receptacles, do we need to extend the size of back box?

 

[infinity]

What's a 2"X4" back box? One of these?

 

[m sleem]

Yes, exactly.

 

[m sleem]

From the attached image i can see #6 opens in addition to #2 opens are hidden, does it mean no need to extend?

 

[infinity]

The box in the photo has 11 KO's, that number is irrelevant. According to T314.16(A) for a 4" X 2 1/8" X 2 1/8" deep you could install 6-#12 or 7-#14 conductors.

 

[kwired]

In order to run two 3/4" conduits in/out from 2"x4" back box of duplex receptacles, do we need to extend the size of back box?

Outside of physical size and restrictions that naturally come up because of it - number of conductors filling the box are generally going to be your limitations. It is possible to enter the box pictured with too many conductors from just a single 1/2 inch raceway.

 

[Dennis Alwon]

They do make deep handy boxes that are 2 1/8" deep. Again as others have said it has nothing to do with the conduit size but rather on the number of conductors.

 

[kwired]

They do make deep handy boxes that are 2 1/8" deep. Again as others have said it has nothing to do with the conduit size but rather on the number of conductors.

Those are easily overfilled with the capacity of just a single 1/2 inch raceway entry as well.

If you plan to have full raceways, you will need boxes with volume for the conductors. Handy boxes are only intended for the associated conductors of the installed device and have no volume for much anything else.