[mr480]

I have a upgrade from 600amp to 1000amp service there are 2 3" conduits from breaker up to weather heads I am pretty sure I need 3 sets of 500mcm per phase can I change the 3"conduits to 4" and split up the phases in that short distance.

[tkrussell]

Your pretty sure?

All conductors of a system must be run together, either bundled or in a raceway.

So, all three phase and one neutral of each set must be together.

If you have more than one set in a raceway, you may need to derate.

Assuming 4- conductors for a three phase four wire system, 500 MCM copper wire with THHN/THWN insulation, I would have three 3 inch conduit risers.

[stanfortyman]

I have a upgrade from 600amp to 1000amp service there are 2 3" conduits from breaker up to weather heads I am pretty sure I need 3 sets of 500mcm per phase can I change the 3"conduits to 4" and split up the phases in that short distance.

I agree with TK, you are "pretty sure"? This is something I would think you would want to be certain about BEFORE doing it.
There is a lot of money at stake if it is done wrong.

Who is doing this work? You or an electrician?

[mr480]

I agree with TK, you are "pretty sure"? This is something I would think you would want to be certain about BEFORE doing it.
There is a lot of money at stake if it is done wrong.

Who is doing this work? You or an electrician?

Pretty sure was a figure of speech just wanted to know about running
9 500mcm's in 2 4" conduits for a lenghth of 10' from breaker to weatherhead and no there is no nuetrals coming from the power company just 3 phase 480 off of the transformer. I have 3 3" running to the station.I really don't have room in enclosure to add another 3" to the top of the can so I thought about upsizing pipe at the pole only.Waiting on specs from breaker company I may need to change enclosure size so that will fix my problem.

[tkrussell]

Will each of the two 4" have 9 - #500 MCM?

For a 1000 amp you only need 3 sets of 3 - #500 MCM

Something does not make sense.

If I am reading you correctly, you have 3 - 3 inch conduits already.

Perhaps some photos of what you have will help you explain.

I still do not know what type of insulation the 500 MCM has or will have.

[mr480]

Will each of the two 4" have 9 - #500 MCM?

For a 1000 amp you only need 3 sets of 3 - #500 MCM

Something does not make sense.

If I am reading you correctly, you have 3 - 3 inch conduits already.

Perhaps some photos of what you have will help you explain.

I still do not know what type of insulation the 500 MCM has or will have.

Thhn insulation existing is 2 3" want to change out to 2 4" because of the room put 9 total 500's in 2 4" conduits.

[tkrussell]

How do you plan to split 9 - 500 MCM , which I believe is your 3 sets of three?

Keep in mind, all three legs of each set must be run together.

4 inch GRC or PVC Sch 40 can only hold 7 - #500 MCM THHN/THWN.

Be sure your "thhn" is dual rated as THHN/THWN.

Also keep in mind, that one you have more than 3 current carrying conductors in a raceway, you need to derate.

If you use 3 - 3 in rises each for 3 - #500 MCM you do not need to derate.

[mr480]

We must be on a different page I know I need 3 of each phase for a 1000amp I know I cannot fit 9 wires in 2 3" conduits you can only put 4 each which leaves 1 left over therfore i will need to add a conduit but do to space I would like to replace existing 3" conduits with 4" and put 5 in one of them and 4 in the other what Ive been asking is will it hurt anything

[tkrussell]

In my first post, I addressed this question

All conductors of a system must be run together, either bundled or in a raceway.

So, all three phase and one neutral of each set must be together.

You cannot split up the phases.

You cannot run 5 in one and 4 in the other.

You may run 6 in one conduit and 3 in the other
Conduit.

And, then, if you do run 6 in one conduit, it is more than three current carrying conductors, you must derate the 6 conductors that would be together.

[mr480]

In my first post, I addressed this question



You cannot split up the phases.

You cannot run 5 in one and 4 in the other.

You may run 6 in one conduit and 3 in the other
conduit.

And, then, if you do run 6 in one conduit, it is more than three current carrying conductors, you must derate the 6 conductors that would be together.

Thanks that is what I was not sure of

[tkrussell]

OK, now that I got my point across, can you tell me why phase conductors can not be split up?

Also, what is your background?

[mr480]

OK, now that I got my point across, can you tell me why phase conductors can not be split up?

Also, what is your background?

Painter

[tkrussell]

So I will guess that you do not know why the phase conductors cannot be split.

[mr480]

So I will guess that you do not know why the phase conductors cannot be split.

No I don't