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Odd vs Even Single Feeder runs

Odd vs Even Single Feeder runs

Odd vs Even Single Feeder runs

(OP)
I came up to this interesting question yesterday and it got me curious...
 
Suppose I require a ~1500A feeder and I have flexibility of choosing  either 3x1c-#350/ph or 4x1c#250/ph. Which one would be the better practical choice? Is it better to always go with even runs for voltage balancing? How about if the run is short, say less than 25m... would it matter?
 
I did a quick capital cost calculation and the #350 was marginally more expensive (~$2.5k more expensive for a 25m run.) However since 350 MCM only requires 9 runs instead of 12 (ie cheaper installation cost), would that bias the decision?
 
Note, the 1500A ampacity is just a number for example illustration purpose. My question isn't about cable ampacity question. My question is directed on the pros/cons of choosing even single cable feeder runs vs odd single cable runs.
 
 

RE: Odd vs Even Single Feeder runs

Many things to consider, but I never have heard that one should consider odd v. even number of parallel conductors.  Ultimately it is probably an economic decision, but you have to include the installation costs, not just the conductor costs.  Depending on conduit sizes involved, it may be that installing more smaller conductors in more smaller conduits is less expensive than installing fewer larger conductors in fewer larger conduits.  But if you only have room for three penetrations through a beam somewhere along the route it doesn't matter how attractive four parallel runs might be for the rest of the run.

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