Artical 240

[souradnik]

In artical 240.4(B) it allows an overcurent device to be upsized when the ampacity of the device does not fall into the standard ranges. Does this artical apply to Service wires or is it for branch circuits and feeders only?

 

[augie47]

It applies to all conductors enumerated in (1), (2) and (3) of that section.
Note it is generally accepted that the load shall not exceed the ampacity of the conductor

 

[Smart $]

FWIW, 230.90 Exception No. 2 specifically permits 240.4(B) to be applied to a service OCPD.

 

[bphgravity]

And, the allowance doesn't apply for every branch-circuit or feeder. Take motor branch-circuits and motor feeders for example. The "next size up" provision does not apply to branch-circuits protected per 430.52(C)(1), Exception No. 2 or feeders protected per 430.62.

 

[augie47]

Nor does it apply to transformer secondary conductors. See 240.21(C)

 

[mjf]

nor does it apply to services over 800 amps

 

[Smart $]

nor does it apply to services over 800 amps

Not exactly... :blink:

It don't apply where the service OCPD is over 800A.

The service itself could be over 800A, using multiple service disconnecting means.

 

[iwire]

It don't apply where the service OCPD is over 800A.

The service itself could be over 800A, using multiple service disconnecting means.

Which in my area is a standard tactic to also avoid the GFP requirements that kick in at 1,000 amps for services over 150 volts to ground.

 

[mjf]

nor does it apply to services over 800 amps

Not exactly... :blink:

It don't apply where the service OCPD is over 800A.

The service itself could be over 800A, using multiple service disconnecting means.

Yes, good clarification!

 

[teco]

Which in my area is a standard tactic to also avoid the GFP requirements that kick in at 1,000 amps for services over 150 volts to ground.

Exactly! Can win a lot of jobs that way.