Space around top and sides of box


Old 04-19-10, 11:24 AM
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Space around top and sides of box

This is probably a simple question, but how much space is allowed to be between the top and sides of box and non-combustible material (drywall)? I've read 1/8" and the only reason I'm double checking it is because I had a quad outlet box installed by a professional electrician and there's over 1/8" gap on the top and bottom (very tight on the sides though). I'm getting ready to have my inspection and, if it's necessary, I'd rather just patch the extra space myself rather than have the electrician come back.

On a related note, I have some boxes that were already in my house with more than 1/8" gap. If I replace the outlets in those boxes, is the inspector going to fail me on that or is it grandfathered? Even if it's grandfathered, is there a safety reason for that gap such that I should just try to fill it in anyway?
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Old 04-19-10, 01:10 PM
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A gap of up to 1/8" is allowed around flush boxes regardless of wall type. In a non-combustible wall the box may be recessed up to 1/4". In a combustible wall the box must be flush with or proud of the finished surface.

Sealing the gap is unimportant on interior walls as long as the faceplate covers it. You can reduce drafts by sealing the gaps around boxes in exterior walls.

Where the gap is larger than 1/8" in drywall, plaster or similar, the code just says it must repaired. It does not specify how the repair be accomplished (drywall mud, caulk, expanding foam, etc).

I doubt the inspector would fail this unless the gap was unreasonably big. A gap approximately equal to the kerf of a keyhole saw or rotozip bit is typically about 1/8" plus or minus a little bit.
Old 04-21-10, 03:45 PM
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Since it doesn't seem like a safety issue that I should do anyway, will the existing boxes with gaps larger than 1/8" be grandfathered in or will I have to fill it in somehow?
Old 04-21-10, 04:54 PM
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The inspector will probably not look at the work that is existing. You could patch it. It may help you save some energy if they are on outside walls.

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