Branch Circuits and Feeders vs. Service Conductors

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curiousgeorge

New member
Location
United States
Why do you need larger conductors for a branch circuit or feeder than you do to supply the same amperage as a service.

For example:

100 amp Service can be fed with 4 cu

100 amp feeder for a subpanel must be 2cu

Anyone?

Much obliged
 

iwire

Moderator
Staff member
Location
Massachusetts
Why do you need larger conductors for a branch circuit or feeder than you do to supply the same amperage as a service.

For example:

100 amp Service can be fed with 4 cu

100 amp feeder for a subpanel must be 2cu

Anyone?

Much obliged

100 amp Service for a dwelling unit can be fed with 4 cu

They are counting on the load diversity that a panel supplying 100% of the load to a dwelling unit will have.
 

dicklaxt

Senior Member
100 amp Service for a dwelling unit can be fed with 4 cu

They are counting on the load diversity that a panel supplying 100% of the load to a dwelling unit will have.


That makes sense but is it written somewhere?????

dick
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
history has shown that the load calculations used in dwellings end up with numbers that always exceed the real usage. In any case, the service wiring is generally mostly outside so the risk from overheating wires is substantially reduced.
 
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