Large, Very Packed Junction Box?????

Hi guys - I ran across the junction box today. I didn’t want to take the cover off, but my client requested so I did.

This box was about 6"X6" square, and had approx 20 wire nuts. This house was wired in sections at different times.

Any advice on if this is an approved installation? I didn’t see any exposed copper, but the fit was pretty tight.

Thanks so much for your help,




Yes box fill is too high. Just roughly if box is 2inches deep we talk about 72 inch3 of volume. Devided by 2.25 minus connections allowances in box. Even without allowance there should not be more than 32 conductors in the box. Recommend evaluation by electrician.

The answer lies in NEC 314.16.

It may be OK if it’s a 3" deep 6 X6.

Just by comparing it to the 4 square to the lower left that looks like an 8x8x4, or 256 cubic inches, or 113 #12’s, or 128 #14’s. I doubt it is over filled.

I think the smallest depth on a 6x6 is 4".

You would need to count the conductors for a box fill calculation. You just cannot do this visually. What may look overfilled may actually be ok.

Agreed…However, if you have other items you are going to put on your inspection report nothing would harm the situation in suggesting the electrician look at this box and look for the label which should tell you the number of conductors allowed. Boxes like this usually have the amount of conductors allowed stamped on the box.