Can I use 1950 junction box with ROMEX® ?

[deguza]

Hello all:

I am planning to rewire my home built in 1950.

The current junction box at an outlet measures 3x2x2, and meets the current volume requirements.

However, when I look at the 314.16(B) table, I see 4" as the height.

Do I have to replace the junction boxes since the height does not match?

Also, does the neutral get counted in the number of wires coming into a box? In other words, If I have a ROMEX® cable coming in, and another one going out of a box, do I use 4 or 6 wires in looking up volume requirements?


Thanks!

 

[Vegas_sparky]

What size conductors are entering the box? Your j box is 12 cu/in.

Each hot, and neutral count. All your ground wires are only counted as 1. IE: (2) 12/2 cables which are spliced has a conductor count of 5. The device mounted to the the box also has to be considered.

 

[Sponsor]

 

[deguza]

What size conductors are entering the box? Your j box is 12 cu/in.

Each hot, and neutral count. All your ground wires are only counted as 1. IE: (2) 12/2 cables which are spliced has a conductor count of 5. The device mounted to the the box also has to be considered.

I have 12 gauge conductors.

It is a receptacle. There may be, say, a light fixture plugged into it.

ROMEX® has three conductors, one for neutral.

 

[Stuff]

You are way over for new wiring. Also need to add if there are internal clamps for the cables. This is usually only in metal boxes.

How I see it:

12 gauge means 2.25 cubic inch per conductor
2 hots = 4.5
2 neutrals =4.5
grounds always count as 1 = 2.25
receptacle (a yoke counts as 2 conductors) = 4.5

Total = 15.75 c.i.

Add internal cable clamps (2.25) and you get 18 c.i.


All of the old houses have boxes that are too small. If you are pulling new cables then you really need new boxes.

The standard box is 3" high where the screws for the receptacle go outside of the box on a tab top and bottom. A masonry box is 4" which is taller than the receptacle and its ears.