SER feeder for 125A subpanel

Rex Hungerford

Senior Member
Location
Seattle
Occupation
Electrician
I am installing a 125A SqD QO MLO subpanel. It will feed a 50 amp range and the counter plugs. As well as a bathroom. And 2 x 1/6 HP Grundfos hydronic heat pump circulators. The run is 80 feet. I want to use 1/0 Al SER.
The load is
50A or 12,000kw
3 x 20A
2 x 5.5 motors.
So roughly 90A per phase.
I want to confirm I am good to use the 75* tables as its SER and the lugs on the panel and the Eaton CH breaker are rated 75* at the terminals. And I can go to the next highest standard breaker which would be a 125A.
 
Yes, #1/0 is rated for 120 amps so next size up is 125 amps. The Eaton breaker terminals would be rated 75° C.
 
Unless you plan on adding significant load to the panel I would not install an larger than 2/3 (2224) SER on a 90 amp breaker. Could get by with 4/3 (4446) on a 60 amp breaker.
 
You don't need 90A for that load. The range would go in at 8KW, the kitchen small appliance circuits at 1.5KW each. The bathroom receptacle circuit is zero unless it is doing light fixtures too in which case it is 3VA per square foot of the bathroom. The motors go in as 5.5A each except one needs to be 125% of that.
 
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