Parallel Conductors

[Seven-Delta-FortyOne]

2 questions:

- 600 amp feed from a generator. I want to run 3 sets of 3/0. Is there an advantage/disadvantage to doing that instead of 2 sets of 350's? It will be a long run, underground, up the side of the building, through a large attic, and out the other side. And I have minimal help. I want to make this as easy as possible.

- The EGC. My understanding is that the EGC must be sized based on the OCPD, not paralleled like the phase conductors, so per 250.122 that would be 1 awg. Is an EGC required in each raceway, or only in one? Sorry for the rookie question on this, but it's been a minute since I did a parallel run, and I'm drawing a blank on how we did it.

Thanks.

 

[infinity]

Yes EGC in each raceway based on 600 amps. 350s would be harder to pull than #3/0. If you have access to a puller the 350s might be better.

 

[AC\DC]

even with a tugger my lazy ass would try for the smallest wire to pull.
Remember you can use 90c and splice on each end I bet you can get a lot smaller size and keep it in three conduits. But if setting up conduit is a pain then do just the two but still us the 90c
I pull by my self so smallest is best!!! And pulleys

 

[winnie]

Is voltage drop a concern? 2 x 350 kcmil has more conductor cross section than 3 x 3/0

 

[Greentagger]

And make sure your lugs will accept your selection of conductors.

 

[petersonra]

Yes EGC in each raceway based on 600 amps. 350s would be harder to pull than #3/0. If you have access to a puller the 350s might be better.

If you decide to use a wire type EGC it has to be full size and in each raceway.

However, if you use a metallic raceway such as RGS, a wire type EGC is not required at all. But presumably an underground run would be in PVC.

 

[Seven-Delta-FortyOne]

I still have to do the VD calcs, it’s over 200’

Nothing is spec’ed, it’s a Tribal job, so real short on details. I end having to do a lot of design myself.

@AC\DC can you explain a little more about this? You’re saying you can size off the 90c table, and then splice a pigtail in the ATS or a J-box with a larger wire size?

@Greentagger that was one of my concerns. We’ll be going into 600A ATS’s, and of course the genset on the other. I’ve seen a lot of terminals that have 2 lugs, less that have 3.

 

[petersonra]

I still have to do the VD calcs, it’s over 200’

Nothing is spec’ed, it’s a Tribal job, so real short on details. I end having to do a lot of design myself.

@AC\DC can you explain a little more about this? You’re saying you can size off the 90c table, and then splice a pigtail in the ATS or a J-box with a larger wire size?

@Greentagger that was one of my concerns. We’ll be going into 600A ATS’s, and of course the genset on the other. I’ve seen a lot of terminals that have 2 lugs, less that have 3.

If you use the 90 deg C column your voltage drop will increase by a lot.

 

[AC\DC]

If you use the 90 deg C column your voltage drop will increase by a lot.

Does he truly need the full 600 amps or is he doing Cause the disconnect in the gen … never done one that big but that can happen on the smaller ones.

 

[AC\DC]

I still have to do the VD calcs, it’s over 200’

Nothing is spec’ed, it’s a Tribal job, so real short on details. I end having to do a lot of design myself.

@AC\DC can you explain a little more about this? You’re saying you can size off the 90c table, and then splice a pigtail in the ATS or a J-box with a larger wire size?

@Greentagger that was one of my concerns. We’ll be going into 600A ATS’s, and of course the genset on the other. I’ve seen a lot of terminals that have 2 lugs, less that have 3.

Correct. Only reason we can’t use 90 column is either wire type or the connection we are terminating to only rated 75.
Your connectors have to be rated 90 though
I do it a lot, it’s hard to pull by yourself

 

[electrofelon]

I did a 600A genny a few years ago (150kw, three phase generators are rated at .8 power factor so 520 amps, had a 600 amp breaker). We did 2 sets of 500 AL in 3" PVC - might have reduced the neutral a little. I had one helper to help me pull it. Wouldn't have wanted to do it alone

 

[hillbilly1]

I work by myself most of the time, but have one of these. I have pulled 3/0 with it before by myself, takes a while on long runs because you have to keep the slack up, but if you have someone feeding, it gives you the strength of two people pulling.

Greenlee G1 Versi-Tugger G Series Drill Puller

The Fluke N5K 6PP54I Power Analyzer is a highly accurate and reliable device for testing and developing power electronics. With its six PP54 Power Phase Input Modules and IEEE488/Ethernet interface, it is compact enough to easily carry and save working space, yet provides all the functionality...

www.electricianshop.com

 

[garbo]

I always considered the price difference between running two larger size wire runs verse running three smaller size runs. ( especially now aways with high copper prices ) Found out if you do not have to do many bends in conduit runs that running three 2" runs of EMT takes almost as much time as running two runs of 3 or 3.5" EMT.