Rookie question

[ggunn]

I apologize for the rookie question, but residential service design is a bit off my map. Regarding 310.12(A), does this allow 2/0 copper service conductors for a single family dwelling to feed a 200A main breaker in an MDP? It seems to, if the "service rating" means the rating of the service disconnect OCPD rating.

 

[jaggedben]

Yes.

 

[GoldDigger]

Not sure whether they still do it, LA DWP had a rule that prohibited installing a smaller main breaker in the service panel to satisfy the 120% rule. They required that the service OCPD exactly match what they called the service size (amperage).

 

[letgomywago]

Not sure whether they still do it, LA DWP had a rule that prohibited installing a smaller main breaker in the service panel to satisfy the 120% rule. They required that the service OCPD exactly match what they called the service size (amperage).

I wonder how they justified that. Or if it was written down somewhere and not just a misunderstanding by someone