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Sub-panel on 100amp breaker failed inspection.

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B

Bcat

New User
Location
New Jersey
Occupation
Electrician
I recently installed a sub-panel (rated at 125amp). It is supplied by #1 SER AL on a 100amp breaker in a 200amp sub panel. The inspector said the maximum breaker I can use is 90amp. Yet I've done the same setup before and passed. I know I can't put #2 SER AL on a 100amp breaker (changed breaker to 90amp to pass), and was told I had to use #1 SER AL. So now I'm confused, and frustrated. Which inspector do I believe? Do I just down size the breaker to 90amp to appease this inspector? Anyone, especially inspectors, care to weight in on this?
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Welcome to the forum.

You are correct. Ask the inspector to look at the ampacity table again.
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
#1 aluminum is rated for 100 amps at 75°C. He's wrong so don't downsize anything.

Welcome to the forum.
 
augie47

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
Was the inspector clear that it was a #1 ??
The improper use of #2 AL on a 100 amp breaker to a subpanel is such a common violation on first sight he may have assumed it was that situation especially if the cable marking was not clearly evident.
(Been there done that myself---didn't caliper the conductor and the cable was secured in a manner the labeling wasn't evident)
 
Jpflex

Jpflex

Electrician big leagues
Location
Victorville
Occupation
Electrician commercial and residential
infinity said:
#1 aluminum is rated for 100 amps at 75°C. He's wrong so don't downsize anything.

Welcome to the forum.
Click to expand...
I don't have code book on hand but isn't 1 awg acceptable for 100 amperes or less at 60 degreed termination
 
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
I would start by asking the inspector what code section was violated.


Jpflex said:
I don't have code book on hand but isn't 1 awg acceptable for 100 amperes or less at 60 degreed termination
Click to expand...

My guess is that he's thinking of 110.14(C)(1) but that 60 degree C limitation wouldn't apply with 75 degree terminals.
 
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