ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Architect wants to put receptacles and switches recessed in a shallow framed wall.
I normally do not size the boxes, but Arch wants to know how shallow can the framed wall be outside face to rear of cavity (depth of a device box).
Maybe just see if my thought process is right.
These will be 20A circuits, but I will not show exact wiring on my drawing and it will be left up to the EC, so when I calculate a typical device box size per 314.16(B), I'm imagining one circuit per box and some devices will feed through to another recept or switch. If they want to put more than one circuit in that area, then it will be routed in separate boxes. If they want to "T" tap a circuit, they will be forced to run the long way.
So I calculated for a typical run (2) conductors for incoming, (2) for outgoing, (1) ground, (1) internal clamps (MC cable), (2) device. For (8) "#12AWG conductors", I get 8 x 2-1/4 = 18CuIn. If that is correct, then the standard device box for 18in^3 is 3"x2"x3-1/2".
So dimension from outside face of wall surface to rear of wall cavity, would be 3-1/2". Or do I need to tell them 4" to be safe?
I normally do not size the boxes, but Arch wants to know how shallow can the framed wall be outside face to rear of cavity (depth of a device box).
Maybe just see if my thought process is right.
These will be 20A circuits, but I will not show exact wiring on my drawing and it will be left up to the EC, so when I calculate a typical device box size per 314.16(B), I'm imagining one circuit per box and some devices will feed through to another recept or switch. If they want to put more than one circuit in that area, then it will be routed in separate boxes. If they want to "T" tap a circuit, they will be forced to run the long way.
So I calculated for a typical run (2) conductors for incoming, (2) for outgoing, (1) ground, (1) internal clamps (MC cable), (2) device. For (8) "#12AWG conductors", I get 8 x 2-1/4 = 18CuIn. If that is correct, then the standard device box for 18in^3 is 3"x2"x3-1/2".
So dimension from outside face of wall surface to rear of wall cavity, would be 3-1/2". Or do I need to tell them 4" to be safe?