Pancake box capacity

Status
Not open for further replies.
G

GerryB

Senior Member
Location
woodbridge, ct. USA
I was talking with another electrician and he said you really can't use a 4" pancake box for a light fixture, cubic inch capacity of 6 cubic inch. They way I read 314.16(B) it looks like one 14-2 or one 12-2 bx is ok but 14-3 or 12-2 romex or mc wouldn't fly. I have never failed an inspection with a 4" pancake box with one cable in it, but I guess you could. Comments? What about a fan pancake box?
 
JFletcher said:
314.16(I) exception exempts the fixture wires for count if under 4 (16ga?) conductors; I dont have the book in front of me atm.
Click to expand...

314.16(B)(1) Exception:

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.
 
Pancake box has a capacity of 6.0 CU".

One 14-2 requires a minimum 6 cu" capacity. Anything more than that is a violation.

12-2 requires 6.75 cu" capacity, so technically you can not have 12-2 in a pancake box.

Just because you have never been called on it it does not mean it is code compliant.
 
echnically the canopy has to be labeled with the cu.in in order to use it. That seems silly , IMO esp, in the case of using a 12/2 vs a 14/2.
 
Dennis Alwon said:
echnically the canopy has to be labeled with the cu.in in order to use it. That seems silly , IMO esp, in the case of using a 12/2 vs a 14/2.
Click to expand...


That's what I thought but I don't see that in Jumpers post. In 30 + years I have never seen a canopy labeled with the cu in amount so I just disregard that.
 
infinity said:
That's what I thought but I don't see that in Jumpers post. In 30 + years I have never seen a canopy labeled with the cu in amount so I just disregard that.
Click to expand...

I've never worried about it either. If it ever came down to it with an inspector there is nothing that says it has to be factory labeled so you write the cubic inch on the canopy.
 
ActionDave said:
I've never worried about it either. If it ever came down to it with an inspector there is nothing that says it has to be factory labeled so you write the cubic inch on the canopy.
Click to expand...

But 314.16 says it has to be marked and it assumes it is factory marked.
 
edward said:
But 314.16 says it has to be marked and it assumes it is factory marked.
Click to expand...

It assumes no such thing.

The volume of a wiring
enclosure (box) shall be the total volume of the assembled
sections and, where used, the space provided by plaster
rings, domed covers, extension rings, and so forth, that are
marked with their volume
Click to expand...
 
ActionDave said:
It assumes no such thing.
Click to expand...

So if you get install a raised cover and/or a dome cover without the volume and you write on it any arbitrary volume you expect the inspector to accept it?

IMO, where it says "marked", I assume it is factory marked not field marked.
 
edward said:
So if you get install a raised cover and/or a dome cover without the volume and you write on it any arbitrary volume you expect the inspector to accept it?

IMO, where it says "marked", I assume it is factory marked not field marked.
Click to expand...

It says marked with the volume. It does not say factory marked and it does not say arbitrarily marked. The volume could easily be calculated and marked on the canopy with a permanent marker if an inspector made a big enough stink about it.
 
ActionDave said:
It says marked with the volume. It does not say factory marked and it does not say arbitrarily marked. The volume could easily be calculated and marked on the canopy with a permanent marker if an inspector made a big enough stink about it.
Click to expand...

I still can not see how I can agree with you.

Based on 314.16(C) says in order to make a splice in a conduit body it has to be marked by the manufacturer.

So I guess you are right because it would have had said similar language for the boxes as it does for the conduit body.
 
jumper said:
314.16(B)(1) Exception:

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.
Click to expand...

ty. the EGC and fixture wires can be excluded if the exception is met, so 12/14-2 (4.5 and 4.0 cu in) and 14/3 (6.0 cu in) can be used in a 6cu in pancake box. 12/3 would be 6.75in3.
 
ActionDave said:
It says marked with the volume. It does not say factory marked and it does not say arbitrarily marked. The volume could easily be calculated and marked on the canopy with a permanent marker if an inspector made a big enough stink about it.
Click to expand...

Per 314.16(A), use Table 314.16(A). Note that if it is not a standard box, 314.16(A)(2) requires it to be marked by the manufacturer if it is not in the table, or under 1003in, or non-metallic.
 
JFletcher said:
ty. the EGC and fixture wires can be excluded if the exception is met, so 12/14-2 (4.5 and 4.0 cu in) and 14/3 (6.0 cu in) can be used in a 6cu in pancake box. 12/3 would be 6.75in3.
Click to expand...

You ma omit If the conductors enter from the dome. But when the conductors enter through the box then you still count the EGC of the NM cable.
 
Status
Not open for further replies.
Top