Guys, is it typical to install a parallel setup with all of your conductors in the same conduit? I have a set of plans here that call for two sets of 2/0 to be installed in a 3" conduit for a 200 amp 3 phase panelboard. The run is only about 80'...
is it typical?
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It's done all the time. The only real issue would be the need to derate due to having more than 3 current carrying conductors in a raceway.
The real issue here is why someone would parallel 2 sets of 2/0 for a 200 amp feeder when all you need is 1 set of 3/0. Seems like a waste of copper.
The real issue here is why someone would parallel 2 sets of 2/0 for a 200 amp feeder when all you need is 1 set of 3/0. Seems like a waste of copper.
and here is another question I have. In calculating the load side or feeder for the transformer I have applied a continuous load calculation. primary calls for 90 amps so I feed the transformer with #2 copper. Do I have to apply continuous load to the secondary conductors?
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yes the secondary ocpd must be sized per 125% continuous load and the wire must be sized accordingly. dont forget to derate the wires as well if its three phase.
Can you show me a code article that requires the overcurrent protective device to be 125% on the secondary side.
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215.3 is for feeders that supply both continuous and noncontinuous load. This mean that the feeder must be sized at 100% for noncontinuous loads and 125% for the loads that are continuous. That does not mean the overcurrent protective device on the secondary must be 125%. I believe 125% is the max it can be set to-- look at table 450.3(A)
I am no expert on this but this is how I see it. In fact sometimes the secondary conductors don't need an ocpd-- look at 240.21(C)
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ok so if you size the feeders for 125% of the continuous load, why not use the max 125% ocpd and get the most out of your transformer? just my two cents. and yes you dont need secondary protection when the transformer is feedin a dedicated load or no lighting or branch circuits.
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