overcurrent protection

Status
Not open for further replies.
From Article 408:

408.36 Overcurrent Protection. In addition to the re-
quirement of 408.30, a panelboard shall be protected by an
overcurrent protective device having a rating not greater
than that of the panelboard. This overcurrent protective de-
vice shall be located within or at any point on the supply
side of the panelboard.
Click to expand...
 
as long as the subpanel is in the same building and the overcurrent protection is sized to protect the conductors and the panel (buss rating), no main is needed at the subpanel.
 
hello! first post here.

For an example, if the main is outside rated at 200 amps. the cuductors are 2/0 going to a 100 amp sub panel directly from to 200 amp breaker. . is this not compliant?
 
milkman6453 said:
hello! first post here.

For an example, if the main is outside rated at 200 amps. the cuductors are 2/0 going to a 100 amp sub panel directly from to 200 amp breaker. . is this not compliant?
Click to expand...


That would not be compliant since the overcurrent protective device is larger than the rating of the panel.. 408.36
 
If the 100A subpanel has a 100A main breaker it would be OK, yes?
The "directly from to" statement is unclear. I do not Dee it as saying from a 200 main (service disconnect?) to a 200 main in subpanel.
More likely "from the 200..."
 
milkman6453 said:
hello! first post here.

For an example, if the main is outside rated at 200 amps. the cuductors are 2/0 going to a 100 amp sub panel directly from to 200 amp breaker. . is this not compliant?
Click to expand...

Dennis Alwon said:
That would not be compliant since the overcurrent protective device is larger than the rating of the panel.. 408.36
Click to expand...

Dennis can correct me if I'm mistaken, but I believe that one possibility of such an installation being complaint would be if your 2/0 conductors met the tap rules in 240.21 and your subpanel had a 100 amp main to conform with 408.36 and 240.21

(the other "not likely" scenario would be the 2/0 are "whole house feeders" and the sub has a 100 amp main)
 
Last edited:
augie47 said:
Dennis can correct me if I'm mistaken, but I believe that one possibility of such an installation being complaint would be if your 2/0 conductors met the tap rules in 240.21 and your subpanel had a 100 amp main to conform with 408.36 and 240.21

(the other "not likely" scenario would be the 2/0 are "whole house feeders" and the sub has a 100 amp main)
Click to expand...



that is actually how my manufactured home is. this isn't for a customer. I recently did this. the sub panel is protected by a 100 amp breaker.
the knuckle head who put the oversized cuductors in was a mad man! iit's only 20 feet from my 200 amp main. I'll have to review the tap rules thank you!
 
Is the 100 amp breaker at the source of the feed or in the sub panel?

I agree with Gus. Easiest fix would be install a 100 amp breaker at the main panel.
 
Status
Not open for further replies.
Top