Size of ground wire


Old 07-11-06, 01:55 AM
Thread Starter
Join Date: May 2006
Posts: 10
Size of ground wire

I've heard the general rule for the ground wire when running #8 or #6 in conduit is that it can be one size smaller, is that right? So, for a 4-wire run, I'd use 3 x #8 with a #10 ground?

BUT, then I see that #6 Romex still has only a #10 ground. Why?
Sponsored Links
Old 07-11-06, 05:02 AM
Speedy Petey's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Nov 2003
Posts: 2,455
There is NO "general rule".
We use Table T250.122, which sizes the grounding conductor according to circuit amperage size.

Up to 30 amps the ground must match the circuit conductors.
For up to 40 & 60 amp circuits the ground size is #10cu.
For up to 100 amp circuits the ground is #8cu.
...and it goes on from there.

Keep in mind, if you upsize the circuit conductors for any reason you must also upsize the ground accordingly.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread
Display Modes