Different circuit sizes in the same gang box

[jjscott]

I have an existing single gang box with a 20 amp outlet in it (12/2 wire) and want to replace it with a dual gang box so I can add a 15 amp light switch (14/2 wire) to it.

It is my understanding that this would not be a code violation or cause any issues. Can you confirm this is correct?

I realize that the hot & neutrals for both circuits can't be tied together, but someone mentioned that the grounds from both circuits should be tied together. Is this true?

If so, how would this work? Wirenut the grounds from both circuits and two pigtails together and then have one pigtail wired to the ground terminal on the 20 amp outlet and the other pigtail wired to the ground terminal on the 15 amp light switch?

 

[yatg]

You're fine. Multiple circuits in the same box are OK. Just like you said, keep the hots and neutrals from each circuit separated, join the grounds, ground the box if its metal.

 

[jjscott]

You're fine. Multiple circuits in the same box are OK. Just like you said, keep the hots and neutrals from each circuit separated, join the grounds, ground the box if its metal.

Is it a requirement to tie the grounds from both circuits together or just best practice?

 

[yatg]

Its required. NEC 250.148.

 

[MikeF2316]

Its required. NEC 250.148.

You'd be hard pressed to keep a couple of 6 inch bare copper wires inside a 4" square metal box not connected!