What is the purpose of parallel feeders?

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augie47

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Tennessee
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State Electrical Inspector (Retired)
Parallel vs single feeders is normally a result of cost (labor and materials) and ease in working the wire. For instance, it is often easier to handle and terminate parallel 3/0s vs single 500s.
You obviously have to compare wire and conduit costs.
 

infinity

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New Jersey
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Journeyman Electrician
In many cases parallel feeders are not only an economical choice but the only choice. Think about how you would run a 1600, 2000, 3000 or 4000 amp feeder without paralleling? (You could run bus duct). ;)
 

Barndog

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Location
Spring Creek Pa
In many cases parallel feeders are not only an economical choice but the only choice. Think about how you would run a 1600, 2000, 3000 or 4000 amp feeder without paralleling? (You could run bus duct). ;)

Thats what i was thinking there are sometimes when paralleling is just about the only option.
 
Even paralleling has options

Even paralleling has options

I do a lot of gensets, quite a few with 800A output CBs. A lot of engineers draw the SLD with (2) 600MCMs paralleled, which ensures 100% capacity for the 800A output (vs. 2 500 mcms which is only 760A, still code legal). However, I would bet $100.00 that none of the EE's that select that parallel size have ever, ever, ever field bent 600MCMs in the small alternator control box (and pulled em in, etc.). Also, std. lugs on CB's are 3 barrel on 800A CB's. So the best answer is (3) parallel 300MCMs per phase. And when you look at the conduit, you'll find the materials for the triple set cheaper than the larger double set. But the EE's don't get it (well, those that have no field experience).
 
Also-total MCM

Also-total MCM

In the previous post, I should have also mentioned that one way has 1200 cm's per phase and the other has 900. With today's price for copper, unless long runs dictate more cm's for less VD, the parallels save on wire, conduit, labor, etc.
 
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