letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
That's because he's thinking the sizing is for voltage drop.
If he's not going to budge do a fused disconnect and a full size breaker
A/C wire size.
- Thread starter Daja7
- Start date
If he's not going to budge do a fused disconnect and a full size breaker
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
Given 250.122(B), that's not enough info to decide if #10 is sufficient. If you used #6 Cu conductors on your 40A circuit due to voltage drop, then you'd have to upsize the #10 EGC to #8.
Cheers, Wayne
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Another case where that technically applies is, when converting a 240v electric range circuit using #6NM w/a #10 EGC to a 120v gas range circuit, the #10 EGC is now not large enough for a 15a breaker.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
I believe that he knows better, and is merely claiming that to throw his weight around.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
If that's truly the case, then I agree. But there are other reasons one might use a larger wire than needed.
letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
But there isn't anything to say that it's not.
When over 10-2 romex I go straight to 6-3 SER. It is cheaper and AC disconnects arr dual rated and it has an oversized ground anyway.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Sure there is: If "why" matters, ask the person who chose the wire size.
Absolutely! And it's easy to transition to copper for loads that require it.
letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
"Why" assumes that whoever you're talking to understands something on that level
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
You mean the electrician or the inspector (both of whom really should know!)?
"That wire is larger than needed. Is that for voltage drop?"
"No."
letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
Remember half of people are bellow average.
After realizing half of electricians are below average was when I had to explain that a hardwired hot tub still needs gfi here in Oregon where they don't require gfi on normal dedicated circuits and that back in WA multiple competitors didn't know that you had to size overcurrent to the hvac max ampacity not just match the wire like 30a is good for everything even from inspectors that I'm gonna just do me when silly stuff comes up.
letgomywago
Senior Member
- Location
- Washington state and Oregon coast
- Occupation
- residential electrician
Now there aren't any provisions in the code to indicated that am oversized wire isn't for voltage drop
- Location
- New Jersey
- Occupation
- Journeyman Electrician
This entire 250.122(B) code section needs to go away or at least be rewritten to the point where questions like this never come up again.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
As I have said before, it should be written to apply only to cases where the upsizing was done specifically for voltage drop, and the AHJ should decide if that is the real reason. I'll add I think that the exception should still be there.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
That would work now someone needs to write it up.
Also if you have a metal raceway that is a listed EGC then 250.122(B) shouldn't even apply.
Eddie702
Licensed Electrician
- Location
- Western Massachusetts
- Occupation
- Electrician
Per the table above 250.122 the equipment grounding conductor is sized based on the overcurrent protection. Has nothing to do in this case with the size of the ungrounded conductors. As long as the overcurrent protection does not exceed 60 amps a #10 is adequate
wwhitney
Senior Member
- Location
- Berkeley, CA
- Occupation
- Retired
No, that's the whole point of 250.122(B), sometimes the table isn't adequate.
Cheers, Wayne
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Agreed. The times that it may not be adequate are most likely due to voltage drop and not much else as illustrated by several of the scenarios in this thread. Remove a VD drop situation from a normal installation and then you should be able to ignore 250.122(B)
kwired
Electron manager
- Location
- NE Nebraska
I've seen many instances in irrigation applications where long distances inhibits rapid opening of overcurrent protection. Many times a component will fail and open a circuit instead of the overcurrent device opening the circuit on short circuits or ground faults. Same fault condition without long conductor runs would open same overcurrent device pretty rapidly.
jaggedben
Senior Member
- Location
- Northern California
- Occupation
- Solar and Energy Storage Installer
So were the EGCs upsized on these installations per 250.122(B)?
- Occupation
- Licensed Electrician