jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
I think most of us understand that. :grin:
In that case the NEC was not followed and it could lead to a hazard.
But there are sections in NEC that allow the breaker or fuse to have an ampacity greater than the conductors.
With the NEC when wiring a motor the breaker often provides only short circuit or ground fault protection of the conductors. The additional motor overload devices protect both the motor and the conductors.
Take a look at 230.90 Exception 3, it allows the over-current protection of service conductors to exceed the rating of the conductors.
Here is a picture I have posted many times, showing a fairly typical service in my area. In this one the conductors in the riser (top left heading up) are rated around 250 amps, with over-current protection of 600 amps. (six 100 amp breakers)
What do you call those SE flanges used where the cable enters the building? Got a link? I have not seen them before.
