We've been debating the "legality" of pancake boxes on several jobs, so I thought I'd throw it out here...

3 1/4 x 1/2 Raco pancake is 3.9 cu in; 4 x 1/2 Raco is 6 cu in. There are also several "blocks" that fit over vinyl with varying cu in capacity.

Fill factor - #14 - 2 cu in per conductor plus 2 cu in for all grounds = 6 cu in (no clamps - black button for connector).

So, 3 1/4 can't be used anywhere, but 4" is ok for typical outside light next to door.

Right or wrong? How do you guys do it? Rough in - a wire poked out next to the door, and then comes finish......

Thanks for input / discussion.

The box fill rules allow including additional volume from added sections.


The people making the boxes do not know that the box will be used without a domed cover with a marked volume.

In the end it is up to the installer to use the boxes code compliantly.

Bob

Do you think the fixture canopy has any allowance?


The total box volume is determined by adding the individual volumes of the box components. The components include the box itself plus any attachments to it, such as a plaster ring, an extension ring, or a dome cover.

I think a dome cover is a canopy.

I just can not remember seeing any with a marked volume which is part of the requirement.

iwire...I'll agree with you that a dome is a canopy....and I have yet to see a cover that has a volume stamped on it.

Seems we posted at about the same time, but you had a quicker trigger finger (I still "hunt and peck" on the key board)

I typically buy it if it has (1) 14-2 in it.

So, we're all talking about the 4" pancake, not the 3" one - right?

I agree that the dome or canopy does increase the volume, but marked?.....

So why do we continue to see the 3" pancake sold/ manufactured?

Thanks for the continuing dialog....

My answer fits either.


They make what sells and pancake boxes sell.


Bob

At this point, we are talking about a box smaller than 4" (your 4x1/2" IS 6 cu.in - so it's "legal" for the one 14/2 romex).

The smaller box (I haven't seen a 3 1/4 x 1/2" box, but a 3x 5/8" box) is what we are on.


Here's an interesting article from Mike Holt:
Outlet Box sizing

The page is dated 2002.

Q:
Domed Fixture Canopy [314.16(B)(1), Ex.].
A round 4 x 1/2 in. box has a total volume of 7 cubic inches and has factory internal cable clamps. Can this pancake box be used with a lighting luminaire that has a domed canopy? The branch-circuit wiring is 14/2 nonmetallic-sheath cable and the luminaire has three fixture wires and one ground wire all smaller than 14 AWG.
(a) Yes (b) No

A:?

(Check the link for answer )


********
EDIT:
iwire...seems the proper term is a DOMED fixture CANOPY

LOL

[This message has been edited by Celtic (edited 04-03-2006).]

I agree iwire....

On another "point of discussion" - this has been ongoing discussion for a while on several jobs.....

The ground wire. tie to the pancake, or to the fixture bar, or both? Fixture bar gets connected to the pancake, so no need to to take bare ground to pancake, just loop the braided "luminere" [sic] ground wire to the fixture bar, nut it to the 14/2 NM ground, and done......

Grov

Ummm, no. That would be like using the ground screw on a switch or receptacle yoke to ground the metallic box.

-Hal

I always hear about how a 6 cu/in pancake is not big enough for a 12/2 but have you ever figured out how much too small it is?
A "ring" about 1/8" thick (.119") would get you over the 6.75 cu/in you need.
It won't take much of a canopy to let me say it is OK.