Overhead service conductors

[Danielt]

I have a service referred to as 400 amps, with three 200amp main breaker panels. The total calculated load is about 300 amps, so they call for 500 AL (310 amps) for the service conductors per 230.23. It seems like a few added pieces of equipment and the 500 will be overloaded, while the three 200 mains are fine.
It seems like an obvious violation. I've been all through 230. What am I missing?

 

[augie47]

Service conductors are only required to have an ampacity not less than the maximum load (230.42_)
230.90 exception allows the sum of the service overcurrent protection devices tom exceed the conductor ampacity where there are multiple disconnects.

 

[Danielt]

I'm with you. I was hoping I missed something. It seems like a recipe for disaster.

 

[augie47]

I'm with you. I was hoping I missed something. It seems like a recipe for disaster.

agree. It does require folks adding loads to take conductor ampacity into consideration,.

 

[infinity]

I have a service referred to as 400 amps, with three 200amp main breaker panels. The total calculated load is about 300 amps, so they call for 500 AL (310 amps) for the service conductors per 230.23.

I wouldn't call that a 400 amp service. You can always use larger conductors if you want.

 

[Danielt]

agree. It does require folks adding loads to take conductor ampacity into consideration,.

I can't imagine anyone adding a load to check the size of the OH service conductors.

I wouldn't call that a 400 amp service. You can always use larger conductors if you want.

I'm reviewing some plans. If it's code legal, it passes, whether I like it or not.

Thank you, gentlemen, for your responses

 

[infinity]

I'm reviewing some plans. If it's code legal, it passes, whether I like it or not.

Yes it's code compliant. Often not the best design is still acceptable. The NEC actually tells us that.

90.1(B) Adequacy. This Code contains provisions that are considered necessary for safety. Compliance therewith and proper maintenance result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.