Difference between switchboard amperage

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Tainted

Tainted

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Engineer (PE)
I did a service load calculation for a building. It requires minimum 208V 3-phase 3000 amp switchboard.

I will intentionally oversize it to 4000 amps instead of providing 3000 amps because I have no idea what future loads the building will need in years from now.

What is the difference between a 3000 amp switchboard vs a 4000 amp switchboard besides the cost, and amperage?

Is there any other benefit from going to a 3000 amp switchboard to 4000 amps?
 
Tainted said:
I did a service load calculation for a building. It requires minimum 208V 3-phase 3000 amp switchboard.

I will intentionally oversize it to 4000 amps instead of providing 3000 amps because I have no idea what future loads the building will need in years from now.

What is the difference between a 3000 amp switchboard vs a 4000 amp switchboard besides the cost, and amperage?

Is there any other benefit from going to a 3000 amp switchboard to 4000 amps?
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Is the Building load actually 3000 amps?
 
Tainted said:
Per article 220, the total came out to be 2100 amps, so minimum switchboard required is 3000 amps. It's a condo apartment building
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IMHO.... The industry as a whole has been focused on energy efficiency which means less amps on loads. Moving forward you will have an extra 900 amps to play with. I would say 4000 amps would be way overrated.
 
xformer said:
IMHO.... The industry as a whole has been focused on energy efficiency which means less amps on loads. Moving forward you will have an extra 900 amps to play with. I would say 4000 amps would be way overrated.
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I get it,

I mean is there any disadvantage of putting in a 4000 amp switchboard instead?

Yes the industry is focusing on energy efficiency, but I feel like the amps are going up too because some building are moving away from gas, which means the demand for electricity is going up, including amps.
 
Tainted said:
I mean is there any disadvantage of putting in a 4000 amp switchboard instead?
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No other than cost. I would opt for the 4000. We did an apartment complex not long ago where they added an 800 amp switchboard just for car chargers.
 
Tainted said:
Yes the industry is focusing on energy efficiency, but I feel like the amps are going up too because some building are moving away from gas, which means the demand for electricity is going up, including amps.
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Since you know which electric appliances are missing from your load calc, and how many if any EVSEs are included, you could easily do at least a ball park calculation that adds in electric appliances and some number of EVSEs and figure out if that exceeds 3000A.

Cheers, Wayne
 
I agree with Wayne. You should have that additional information prior to making a decision.

My projects usually required adding 20% to the calculated load for "future load growth." At present, you are well within that requirement with a 3000 amp service.
 
Just make sure the electrical room/area has enough space for any gear expansion you may envision if your load grows. I have seen more than one oversized lineup that could not be expanded as the electrical designer planned.
 
jim dungar said:
Just make sure the electrical room/area has enough space for any gear expansion you may envision if your load grows. I have seen more than one oversized lineup that could not be expanded as the electrical designer planned.
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There is a lot of space, we convinced them to remove their oil tank for the new electrical room. Mind you, this is an existing building, electrical infrastructure renovation.
 
Tainted said:
Per article 220, the total came out to be 2100 amps, so minimum switchboard required is 3000 amps. It's a condo apartment building
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They do have 2500A rated equipment.
Be sure to run your concerns past the OWNER. If not, brace yourself to be embarrassed after the bids come in. Any good EC is going to offer deducts to bring the price down or back to where it should be.

Following up on JDs comment...make sure horizontal bus is fully rated across AND the last section has FACTORY provisions for adding a section.
 
Tainted said:
I get it,

I mean is there any disadvantage of putting in a 4000 amp switchboard instead?

Yes the industry is focusing on energy efficiency, but I feel like the amps are going up too because some building are moving away from gas, which means the demand for electricity is going up, including amps.
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Plus, if you ever add loads, the current load can be calculated using usage data giving you certainly significantly more than 900 amps headroom.
 
charlie b said:
I agree with Wayne. You should have that additional information prior to making a decision.

My projects usually required adding 20% to the calculated load for "future load growth." At present, you are well within that requirement with a 3000 amp service.
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Why would they do that? We follow the NEC rules for service sizing and NEC is already VERY conservative. We all know that are service sizes are already way bigger than they need to be.
I don't know how many times I have gone to do a renovation on a facility and service barely see 50-60% of the service size, even in industrial applications.
 
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