Feeder Calc

raberding said:
the conductors are protected by the upstream 400a breaker. So it needs 400a conductors. 500kcmil would work. The DEMAND LOAD is only 77a. So if the upstream breaker could be reduced to 100, you could use 100a conductors.
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So to my prior question in my first post I guess I don't need to know the calculated load for the panel the wire is feeding? I would only size the feeder off of the breaker upstream that is protecting the conductors irregardless the panel size it's feeding? So above in first post an 800a breaker is feeding panel. I'd size wire off 800a.
 
Alwayslearningelec said:
So in this example the panel schedule has a total connected load of 279 amps. It being feed from a 400A breaker. I'm assuming wire to the panel should NOT be sized to the connected load because they may( and probably will) add loads. So what would you size the wire to?
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No the conductors are sized according to the OCPD ahead of them. You wouldn't use 300 amp conductors on a 400 amp OCPD. But your question is about voltage drop which is entirely different.
 
infinity said:
No the conductors are sized according to the OCPD ahead of them. You wouldn't use 300 amp conductors on a 400 amp OCPD. But your question is about voltage drop which is entirely different.
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Thanks. So if I have a 800a breaker feeder and 800a panel I don't need to know the calculated load on the panel being fed, I would just size the wire to 800a ocpd?
 
infinity said:
You should use the calculated load of everything connected to that distribution board not a random number.
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raberding said:
. I'd suggest providing 800 amps of conductors. And use 800 for the VD calc.
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Might as well throw another opinion in here: I would use less than the calculates load, probably 66% - 80% of the calculated load.
 
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