Service from utility terminated in enclosure with 2 mains. One main would feed 6 meters and the other main would feed one meter...Is this allowed?

[jaggedben]

Another option would be to present actual known data from a utility and show the 400 amp service is large enough for the existing load and the additional calculated load.

I think the point is that if one looked at demand history and it were low enough it may be possible to add the new load to the existing 400 amps of service conductor, keep existing 400 amp main and add the additional 200 amp main.

Those are both considered load calculations (220.87). So no, that wasn't the point back around post #31. I mean, you might find that 220.87 results in a load calc less than 400A, but you might even find that other methods do as well.

Again, we don't know where the service point is, and it was unclear exactly what was being proposed. I see three scenarios.

1) The conductors coming into the existing 400A breaker are customer owned, and the total NEC load calculation exceeds their rating.
Option A: upgrade the existing customer owned conductors (multiple options for disconnects at the load end)
Option B: install a new set of service entrance conductors all the way back to the service point, wherever that is

2) The conductors coming into the existing 400A breaker are customer owned, and the total NEC load calculation does not exceed their rating.
Option A: Replace existing 400A equipment with 600A
Option B: Tap existing conductors to new 200A alongside existing 400A
Option C: install a new set of service entrance conductors all the way back to the service point, wherever that is
Note: none of these options requires upgrading the existing conductors

3) The conductors coming into the existing 400A breaker are utility owned.
It is up to the utility to decide if the existing conductors need to be upgraded, and they would ask for load information, although it may not need to be calculated according to the NEC.

So regardless of the scenario, some kind of load calculation is going to come into play if you want to know what all your compliant options are.

 

[david]

Those are both considered load calculations (220.87). So no, that wasn't the point back around post #31. I mean, you might find that 220.87 results in a load calc less than 400A, but you might even find that other methods do as well.

Again, we don't know where the service point is, and it was unclear exactly what was being proposed. I see three scenarios.

1) The conductors coming into the existing 400A breaker are customer owned, and the total NEC load calculation exceeds their rating.
Option A: upgrade the existing customer owned conductors (multiple options for disconnects at the load end)
Option B: install a new set of service entrance conductors all the way back to the service point, wherever that is

2) The conductors coming into the existing 400A breaker are customer owned, and the total NEC load calculation does not exceed their rating.
Option A: Replace existing 400A equipment with 600A
Option B: Tap existing conductors to new 200A alongside existing 400A
Option C: install a new set of service entrance conductors all the way back to the service point, wherever that is
Note: none of these options requires upgrading the existing conductors

3) The conductors coming into the existing 400A breaker are utility owned.
It is up to the utility to decide if the existing conductors need to be upgraded, and they would ask for load information, although it may not need to be calculated according to the NEC.

I don't know of any utility in the area that would claim ownership to any conductor entering a building, they would through that back on the NEC requirements, that of course may be different in other local areas.

So regardless of the scenario, some kind of load calculation is going to come into play if you want to know what all your compliant options are.

 

[david]

Those are both considered load calculations (220.87). So no, that wasn't the point back around post #31.

According to the op he never intended to abandon the existing 400 amp supply conductors, he only intended to parallel a set of 3/0 to increase the service conductors capacity to 600 amp

I mean, you might find that 220.87 results in a load calc less than 400A, but you might even find that other methods do as well.

I assume you went back and checked the language in 220.87 and determined that know data is a type of load calculations, it seemed to me you where referring to a mathematic type of load calculation since you didn't make that distinction when known site data was first referred to.

I do however appreciate the fact you are pointing out that the NEC considers know site data on an existing building a type of load calculations.

Since you now clarified that you where considering known site data in your discussion as a load calculation that changes that part of the discussion.

I apologize for the confusion!

 

[rlqdot]

i will admit that i have not read the entire thread and maybe this has been discussed, but does the existing 400 amp main serve a separate customer does it feed the multi-meter cabinet??? those seven meters will be "cold sequence" and some utility companies will not allow a disconnect ahead of their meter. i imagine the existing 400 protects the entire multi-meter cabinet, because if not, there would be 8 existing service disconnects - but thought i would just ask.