80% rule on service breakers

[Jnewell]

Does the 80% rule apply to service breakers? I am trying to figure out if we can add a pool to this service without an upgrade. We are right under 80% of the load calculation without the pool.

 

[texie]

If you have a proper Article 220 calc that says, for example, 200 amp then you can use a 200 amp main breaker. The "80 % rule" has effect here.

 

[jaggedben]

Texie I think you meant 'has no effect'.

 

[infinity]

Does the 80% rule apply to service breakers? I am trying to figure out if we can add a pool to this service without an upgrade. We are right under 80% of the load calculation without the pool.

There is no 80% rule for the size of the service. The load calculation tells you the minimum size of the service.

 

[Fred B]

Other discussion of the 80%rule here:

80% Breaker Rating Rule?

List, I've just discovered that the 80% loading of a breaker rule was eliminated in the 2002 code because calculations required to properly size wire and devices properly compensate and make the 80% rule no longer needed. What amazes me is that it possibly should still be in place for...

forums.mikeholt.com

80% rule

would anyone mind explaining the 80% rule for sizing breakers/wire. someone asked me recently and i couldnt exactly explain it well

forums.mikeholt.com

210.20(A) 80% rule - Main breaker

Does the 125% max rating for continuous loads apply to other than branch CB's? Meaning can I load my Main CB for my service panel close to it's max rating? (Specifically, Got a 200A service 200A Main CB and after renovations, the new loading on the service will be literally 197Amps after a...

forums.mikeholt.com

 

[david luchini]

Does the 80% rule apply to service breakers? I am trying to figure out if we can add a pool to this service without an upgrade. We are right under 80% of the load calculation without the pool.

The service ocpd must be sized for 125% of continuous load plus 100% of non-continuous load, unless it is a 100% rated device.

 

[JoeStillman]

I confirmed with NFPA that all of the loads in the resi calc formula are considered non-continuous, so you don't have to multiply by 1.25.

But EV chargers, which don't seem to appear anywhere in 220, are widely regarded to be continuous and not subject to any of the 220.84 diversity factors. I would probably consider a pool filter a continuous load too.