Oversizing all apartment overcurrent protections

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Tainted

Tainted

Senior Member
Location
New York
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Engineer (PE)
Let's say we have a meter bank with (24) 208V single phase apartments. We feed this meter bank with a 600A switch at 208V 3 phase.

The meter bank allows you to install up to 200 amps for each of the 24 single phase apartments.

Is there any issue if we intentionally provide 200 amp overcurrent device to each of the 24 apartments even though most of them don't even need 200 amps?
 
Tainted said:
Let's say we have a meter bank with (24) 208V single phase apartments. We feed this meter bank with a 600A switch at 208V 3 phase.

The meter bank allows you to install up to 200 amps for each of the 24 single phase apartments.

Is there any issue if we intentionally provide 200 amp overcurrent device to each of the 24 apartments even though most of them don't even need 200 amps?
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You would need to do a calculation based on square footage of all apartments including appliances in each unit, etc.
 
HEYDOG said:
You would need to do a calculation based on square footage of all apartments including appliances in each unit, etc.
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I know, but suppose everything is calculated correctly and the loads are like 100-150 amps for each apartment, and 220.84 complies as well. If we provide 200 amps for each apartment even though they don't need that many amps, would it be an issue?

They are asking me to max out the meter bank and to oversize all the overcurrent protection and I just want to know the justification in doing so.
 
Tainted said:
I know, but suppose everything is calculated correctly and the loads are like 100-150 amps for each apartment, and 220.84 complies as well. If we provide 200 amps for each apartment even though they don't need that many amps, would it be an issue?
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For the individual units, 200a sounds reasonable. The 600a main service may be taxed.
 
I don't see it being a Code issue but it sure increases your cost. You would need 200 amp panels and 200 amp conductors to each unit. Sizing them properly would help alert someone as to the small service if the apt increased their load significantly.
 
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LarryFine said:
For the individual units, 200a sounds reasonable. The 600a main service may be taxed.
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Just playing numbers looking at S/A + Laundry and limited sq footage I think more than taxed, I think it's undersized even with the .35 multiplier
 
augie47 said:
Just playing numbers looking at S/A + Laundry and limited sq footage I think more than taxed, I think it's undersized even with the .35 multiplier
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Just want to clarify, it is not that the 600A is undersized, it is the 200 amps per apartment that is oversized.
 
Tainted said:
Just want to clarify, it is not that the 600A is undersized, it is the 200 amps per apartment that is oversized.
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I don't agree with that assessment; I think the 200a per is appropriate for the load levels you described.

Even if you went with 150a feeders, it would not change whether the 600a is adequate for the building.
 
Likewise... I think you might want to run the numbers... I definitelty could be mistaken but I show the 600 amp being underiszed for 24 units at minimum load
EDIT:
Disregard my concern..late night math error... not a definite problem.....possibly adequate
 
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LarryFine said:
I don't agree with that assessment; I think the 200a per is appropriate for the load levels you described.

Even if you went with 150a feeders, it would not change whether the 600a is adequate for the building.
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100-150 amps I mentioned was just an obscure assumption without doing calculations, but I see your point.
 
augie47 said:
Likewise... I think you might want to run the numbers... I definitelty could be mistaken but I show the 600 amp being underiszed for 24 units at minimum load
EDIT:
Disregard my concern..late night math error... not a definite problem.....possibly adequate
Click to expand...
LarryFine said:
I don't agree with that assessment; I think the 200a per is appropriate for the load levels you described.

Even if you went with 150a feeders, it would not change whether the 600a is adequate for the building.
Click to expand...
If 220.87 is performed on the 600A switch and found to be adequate, would it really be considered undersized even if 220.87 tells us it isn't?
 
Short answer is you can put 600 amp panels in all of the apartments if the load calculation allows it. You said that your 600 amp meter bank is sized properly so there is no issue.
 
Tainted said:
Let's say we have a meter bank with (24) 208V single phase apartments. We feed this meter bank with a 600A switch at 208V 3 phase.

The meter bank allows you to install up to 200 amps for each of the 24 single phase apartments.

Is there any issue if we intentionally provide 200 amp overcurrent device to each of the 24 apartments even though most of them don't even need 200 amps?
Click to expand...

The only issue of using an oversized feeder is the cost of the feeder conductors and the requirement that the apartment panel be rated for 200 amps or have a main breaker that does not exceed the rating of the panel.
 
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