Are people using #12 grounding pigtails when you pull #10's (on a 20A breaker)?

Status
Not open for further replies.
I am resurecting this thread.



Ok I have read what you folks have said and still wonder the following.
SO you cannot use #10nm for a 20 amp circuit?
What about using an existing circuit that is from an Existing Range or dryer and downsizing it for a 15 or 20 amp cicuit and installing the appropriate breaker?
 
Sierrasparky said:
I am resurecting this thread.



Ok I have read what you folks have said and still wonder the following.
SO you cannot use #10nm for a 20 amp circuit? Yes
What about using an existing circuit that is from an Existing Range or dryer and downsizing it for a 15 or 20 amp cicuit and installing the appropriate breaker?
Click to expand...
Yes

From what you have stated, I see no objections. Others will chime in and correct where wrong.
 
Sierrasparky said:
I am resurecting this thread.



Ok I have read what you folks have said and still wonder the following.
SO you cannot use #10nm for a 20 amp circuit?
Click to expand...

Why couldn't you? I don't understand what the question is.


Sierrasparky said:
What about using an existing circuit that is from an Existing Range or dryer and downsizing it for a 15 or 20 amp cicuit and installing the appropriate breaker?
Click to expand...
Again... Why not?
 
Sierrasparky said:
Looking at http://forums.mikeholt.com/showthread.php?t=146402&page=2&p=1417914

You apparrently cannot! I don't agree though.
I guess I did not need to resurrect this particular thread.
Click to expand...

You resurrected it and got confused, or at least you have me confused as to what you're saying.
There is nothing in the thread you linked to that says you can't use 10AWG on a 20A circuit.
What makes you think you couldn't use 10AWG, other than it being hard to terminate on a 20A device?
 
If you had 10-3 I think you could use that on a 20A circuit. If you had 8-3 or 6-3 you could not. The reason is that the ungrounded conductors became larger so the equipment ground must be proportionately larger. If you upsize from #12 to #10, the EGC must be #10, so 10-2 romex is fine. On 8-3 or 6-3 romex, the EGC is #10 which is not large enough for a #8 or #6 conductor.

For 15, 20, and 30 amp circuits, the EGC must be the same size as the ungrounded conductors when you oversize the wire (because the ground and ungrounded are the same size per 250.122). For larger circuit breakers, you have to do the math to see how much larger you need to go. You couldn't legally use 6-3 on a 40A circuit either, but I bet most inspectors wouldn't catch it or care unless the cable run was very long.
 
I initially agreed with finite10 but after reading this lofty discussion, I am with the others.
Littlebill explained it best for me.
 
suemarkp said:
If you had 10-3 I think you could use that on a 20A circuit. If you had 8-3 or 6-3 you could not. The reason is that the ungrounded conductors became larger so the equipment ground must be proportionately larger. If you upsize from #12 to #10, the EGC must be #10, so 10-2 romex is fine. On 8-3 or 6-3 romex, the EGC is #10 which is not large enough for a #8 or #6 conductor.

For 15, 20, and 30 amp circuits, the EGC must be the same size as the ungrounded conductors when you oversize the wire (because the ground and ungrounded are the same size per 250.122). For larger circuit breakers, you have to do the math to see how much larger you need to go. You couldn't legally use 6-3 on a 40A circuit either, but I bet most inspectors wouldn't catch it or care unless the cable run was very long.
Click to expand...

Would you point out where it says the EGC has to be the same size as the ungrounded conductors.

It doesn't say that in 250.122.

Table 250.122 shows the minimum size of breakers for the overcurrent device of the circuit, ...not the size of the ungrounded conductors.

I suppose you are correct about the 10 not being large enough for proportionally upsizing to a # 8 conductor, but it sure seems dumb that you could use a #10 for a 40 amp breaker but not a 20. The resurrection post was about an existing circuit which must have been large enough for the voltage drop in the existing larger circuit.
 
Last edited:
Yep, that rule makes for some things that seem dumb -- I can use this wire for a 40A circuit but not a 20A circuit??? The other bad thing with the upsizing rule is there is no definition on what a "normal" sized conductor is. Is #8 at 75C normal for a 50A circuit? Is #6 at 60C normal or oversized for a 50A circuit. Voltage drop doesn't care about the temperature rating of the conductor.
 
Status
Not open for further replies.
Top