I am biding a project where it calls for removing the 2 4" pipes and adding 3 4" with 4 400kmcil. I did some calculations and was wondering if you guys could check it for me. I figured I could leave the 2 4" pipes and put in 4 750kmcil and it would be the same service give or take 70 amps. The GC is trying to get the cost down and wants some sugestions to send the engineer. Any help would be appreciated!
Service re-sizing
- Thread starter chrsb
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Re: Service re-sizing
Chrsb
The 2 #750's = 950 amps and 3 #400's = 1005 amps.
I think you should check with the designer and see why he called for the 3 #400's. Also you did not mention how old the service was and the condition of the existing conduits. What is the new main size? I would think there is a good reason for wanting to remove the present service.
You probably do not need 4 #750's. See if you can reduce the neutral down.
Chrsb
The 2 #750's = 950 amps and 3 #400's = 1005 amps.
I think you should check with the designer and see why he called for the 3 #400's. Also you did not mention how old the service was and the condition of the existing conduits. What is the new main size? I would think there is a good reason for wanting to remove the present service.
You probably do not need 4 #750's. See if you can reduce the neutral down.
Re: Service re-sizing
The building is 5 years old. The connected load will be 232.1 KVA. The calculated load will be 238.3 KVA. The total amps will be 661.9. The drawings are calling for a 1000A TVSS. 70% of the load will be lighting, it is an nation wide drug store chain. What we are trying to avoid is tearing up the asphalt and keeping the cost down. The last one of these didn't go through because it went over budget.
The building is 5 years old. The connected load will be 232.1 KVA. The calculated load will be 238.3 KVA. The total amps will be 661.9. The drawings are calling for a 1000A TVSS. 70% of the load will be lighting, it is an nation wide drug store chain. What we are trying to avoid is tearing up the asphalt and keeping the cost down. The last one of these didn't go through because it went over budget.
Re: Service re-sizing
Why not put 8-400mcm in each existing 4"? Even with derating, you get 266 amps per, which will give you more than necessary. Even 350mcm gets close. Offhand I cannot remember the derating value for this configuration....70% or 80%..?
Why not put 8-400mcm in each existing 4"? Even with derating, you get 266 amps per, which will give you more than necessary. Even 350mcm gets close. Offhand I cannot remember the derating value for this configuration....70% or 80%..?
Re: Service re-sizing
I never knew you could do that, put more than 1 parellel set into a conduit. I have proposed to make the service 800A. I told them to call the engineer and ask why he spec'd 1000A service, there is an 600A service there now and they are only adding lights on a 1,000 sq' addition, and getting rid of all the large coolers.
I never knew you could do that, put more than 1 parellel set into a conduit. I have proposed to make the service 800A. I told them to call the engineer and ask why he spec'd 1000A service, there is an 600A service there now and they are only adding lights on a 1,000 sq' addition, and getting rid of all the large coolers.
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