Number of Wire Allowed in an Electrical Box

Number of Wires in a Box
Box Type Size Maximum Number of Wires
14 ga. 12 ga. 10 ga. 8 ga. 6 ga.

Octagon

4 X 1 6 5 5 4 2
4 X 1 7 6 6 5 3
4 X 2 10 9 8 7 4

Square

4 X 1 9 8 7 6 3
4 X 1 10 9 8 7 4
4 X 2 15 13 12 10 6

Square

4 11/16 X 1 14 13 11 9 5
4 11/16 X 2 1/8 21 18 16 14 8
Device Box
3 X 2 X 1 3 3 3 2 1
3 X 2 X 2 5 4 4 3 2
3 X 2 X 2 5 4 4 3 2
3 X 2 X 2 6 5 5 4 2
3 X 2 X 2 7 6 5 4 2
3 X 2 X 3 9 8 7 6 3
Handy Box
4 X 2 X 1 5 4 4 3 2
4 X 2 X 1 7/8 6 5 5 4 2
4 X 2 X 2 7 6 5 4 2
Notes to table above
Fixture wires are counted.
A wire entering a box and running out again without splice is counted as only one wire.
Deduct one from the number in the table if a box contains a fixture stud, hickey, or one or more internal cable clamps.  The total deduction is one for each type of these items present in the box.  External Romex or Greenfield connectors are not counted for this purpose.
Deduct two from the number for each switch, receptacle or similar device, or a combination of them if mounted on a single strap.
A wire originating in a box and ending in the same box is not counted.
All bare grounding wires are counted as one wire, no matter how many of them.
 

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Last update: March 18, 2008 05:16 PM
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