Originally posted by Don'tKnowEverythingYet:
Quoting:On large circuits, oversized wire may inpact the available short circuit current requiring breakers with a higher interupting rating.
How?
What if the existing installation has #6 wire and the new equipment requires #12? #6 won't fit under the terminals of a 20A breaker. Can't you pigtail smaller wire onto the #6? Or must you pull new wire?
I think I see where we are talking about several things at once... at least it looks that way now that I read all the responses in sequence.
First of all, I think resqcapt19 meant on the line side - meaning what is available in the panel box. So the CBs would need a rating that was higher than 10000 A.
When he stated that oversized wire may impact the available short circuit current, he meant that it may increase it (in fact, would increase it at least slightly if not a lot).
In talking about oversized conductors it appears that you and I and perhaps others were talking about the load side - meaning what is available somewhere down a distant branch circuit.
Therefore, my questions and responses should be interpreted in the context of being after the OPD in a residential service. I was not thinking of a panel with 65 KA SCA available and then running #8 from a 20 A CB out to my 15 A receptables. However, from Stu T's follow up it appears that this might parallel where he was going... just on the branch side.
[This message has been edited by Dspark (edited 04-24-2001).]
