Parallel Runs

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augie47

augie47

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just to cover the bases, could you provide a bit more detail and what you plan.
 
laketime

laketime

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augie47 said:
just to cover the bases, could you provide a bit more detail and what you plan.
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Sure, plan is calling for 2 1/2" GRC underground with (3) 250mcm and (1) #4 in it.
feeding a 250 amp panel. We might end up going with a 400 amp set up due to costs of the 250 (not a standard item) If we go with the 400 we can parallel the 2/0's in the same size conduit.
 
C

Cow

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laketime said:
Sure, plan is calling for 2 1/2" GRC underground with (3) 250mcm and (1) #4 in it.
feeding a 250 amp panel. We might end up going with a 400 amp set up due to costs of the 250 (not a standard item) If we go with the 400 we can parallel the 2/0's in the same size conduit.
Click to expand...

Since when does parallel 2/0's equal 400 amps? Parallel 3/0's will get you there as long as the calculated load is under 360 amps. Otherwise you'll need parallel 4/0's for the full 400 amp rating.
 
laketime

laketime

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Cow said:
Since when does parallel 2/0's equal 400 amps? Parallel 3/0's will get you there as long as the calculated load is under 360 amps. Otherwise you'll need parallel 4/0's for the full 400 amp rating.
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Table 310.15(b)(6) rates 2/0 copper at 200 amps. I neglected to say this was a service for a SFD.
 
K

ksmith846

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Port St Lucie, Florida
laketime said:
Table 310.15(b)(6) rates 2/0 copper at 200 amps. I neglected to say this was a service for a SFD.
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I don't think you can use that table for parallel runs. Also in one conduit you must derate. 6 Current Carrying Conductors is 80% derate. Can't even use 3/0's. Use 2 conduits from Meter to ATS with 2 sets of 3/0's. Want to save more $$? Get EE approval and run parallel #250 Aluminum.
 
iwire

iwire

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ksmith846 said:
I don't think you can use that table for parallel runs.
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I agree with you, unfortunately the code making panel has said yes you can use that table for multiple runs.



Also in one conduit you must derate. 6 Current Carrying Conductors is 80% derate.
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If you use table 310.15(b)(6) I don't believe there are any derating requirements for numbers of conductors or high temps.
 
K

ksmith846

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iwire said:
I agree with you, unfortunately the code making panel has said yes you can use that table for multiple runs.





If you use table 310.15(b)(6) I don't believe there are any derating requirements for numbers of conductors or high temps.
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I stand corrected.....I do not get to use that table as i do not do many homes.

I would be pushing the EE to allow me to use the parallel aluminum and use high press terminals for all connections.
 
ActionDave

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iwire said:
I agree with you, unfortunately the code making panel has said yes you can use that table for multiple runs.

If you use table 310.15(b)(6) I don't believe there are any derating requirements for numbers of conductors or high temps.
Click to expand...

Is this really a problem? When does the actual load of a single family house ever reach the max amps the service wires could carry?
 
laketime

laketime

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Sounds like parallel runs in separate conduits for me. Do I get to use 310.15(b)(6) for parallel runs in separate conduits?
 
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