Service Sizing

[peterkent]

After using Art. 220 to compute the load for a small apartment, my calculation yields 63A.
Does the NEC permit the use of a 60A service(if so, what article) or is a 100A service required?

Thanks in advance

 

[augie47]

230.79(C) & (D) 100 amp for a one family dwelling, for all others 60 amp

 

[mcclary's electrical]

Smallest SFD is 100

 

[ceb58]

After using Art. 220 to compute the load for a small apartment, my calculation yields 63A.
Does the NEC permit the use of a 60A service(if so, what article) or is a 100A service required?

Thanks in advance

100 amp Min.

 

[iwire]

After using Art. 220 to compute the load for a small apartment, my calculation yields 63A.
Does the NEC permit the use of a 60A service(if so, what article) or is a 100A service required?

Thanks in advance

If the calculation is 63 amps you need at least a 63 amp service.

If it where me I might check over my calculations and find a 3 amp mistake.

230.79(C) & (D) 100 amp for a one family dwelling, for all others 60 amp

That is the disconnecting means only, not the service size.


Usually one in the same with breakers but use a fusible switch and anything goes.

 

[buldogg]

If the calculation is 63 amps you need at least a 63 amp service.

If it where me I might check over my calculations and find a 3 amp mistake.




That is the disconnecting means only, not the service size.


Usually one in the same with breakers but use a fusible switch and anything goes.

If the calculated load is 63 amps, why would anyone even think about trying to get away with a 60A service?

 

[RICK NAPIER]

If your initial computation was for 63 amps I would not try to get it any lower. While it would be code compliant if the calculated load was under 60 amps the calculation methods in the code does not give much latidude for additional loads and no one wants to see problems in the future with the work you do today.

 

[peterkent]

If the calculated load is 63 amps, why would anyone even think about trying to get away with a 60A service?

The 60A service is existing and the owner added a heat pump that is 2.5x larger than the space requires.

 

[Bea]

The 60A service is existing and the owner added a heat pump that is 2.5x larger than the space requires.

Are you trying to make a case for a smaller heat pump?

 

[Bea]

If the calculation is 63 amps you need at least a 63 amp service.

If it where me I might check over my calculations and find a 3 amp mistake.

I would not disagree that you may find a way to lose 3 amps but then again it could go the other way and I would like to say the code book is a minimum and if the calculation is 1 amp above 60 amps then I would size my service accordingly.

 

[peterkent]

Are you trying to make a case for a smaller heat pump?

I doubt the heaters will ever be used at full capacity