Single Phase to Three Phase conversion

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funseebee

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The existing condition is a single phase system. There are 3-500kcmil & 1-#2(ground) cables in a 3" conduit. The feeder run is overhead and underground from the main switchboard to a power distribution panel at approx. 300 ft.
Now, the plan is to convert it to a three phase system in a very cost effective way.
Is it a Code violation to run a new 1-500kcmil in a separate conduit parallel to the existing feeder run?

Any suggestion? Please help. Thanks. :confused:
 
You cannot run a separate conductor in a separate conduit. You could use the existing feeder as a 3 wire, three phase feeder and install a transformer at the end to create a 4 wire system with a neutral but you may have a problem if the existing grounded conductor has white insulation.
 
infinity said:
...but you may have a problem if the existing grounded conductor has white insulation.
Click to expand...
Not if run as a corner grounded delta feed. Depending on the converter type, may have to put a transformer at the source end to get a corner grounded 3? system, though.
 
infinity said:
You cannot run a separate conductor in a separate conduit. You could use the existing feeder as a 3 wire, three phase feeder and install a transformer at the end to create a 4 wire system with a neutral but you may have a problem if the existing grounded conductor has white insulation.
Click to expand...

Hi,
What do you mean by your statement "you may have a problem if the existing grounded conductor has white insulation"?
Please elaborate. Thanks.:confused:
 
1) What kind of conduit is this? What kind of wire (insulation)?

2) What is the reason for wanting the third phase (more power? three phases for rotating equipment? adding a rectifier?)

3) In the new configuration do you need the neutral?

4) Is the second conduit that you are considering already installed as a spare?

5) What is the insulation color on the currently installed wires?

6) Is this an industrial setting?

-Jon
 
funseebee said:
Hi,
What do you mean by your statement "you may have a problem if the existing grounded conductor has white insulation"?
Please elaborate. Thanks.:confused:
Click to expand...

Article 200 outlines when you can re identify a white conductor. If memory serves me correctly this isn't one of them.

A corner grounded Delta feed would require that the system was already a corner grounded system. Not very likely IMO.
 
infinity said:
Article 200 outlines when you can re identify a white conductor. If memory serves me correctly this isn't one of them.

A corner grounded Delta feed would require that the system was already a corner grounded system. Not very likely IMO.
Click to expand...

you are correct, you can re-identify a ungrounded color to a white, in a raceway if it is a #6 or larger, but only cable assemblies can you re-identify a white as a un-grounded conductor, no size restrictions.

see 200.3(C):wink:
 
hurk27 said:
you are correct, you can re-identify a ungrounded color to a white, in a raceway if it is a #6 or larger, but only cable assemblies can you re-identify a white as a un-grounded conductor, no size restrictions.

see 200.3(C):wink:
Click to expand...

That's why I said white conductor. If the original single phase installation used white tape on the grounded conductor then it can simply be removed and made into a phase conductor. That would provide a three phase feeder which could feed a transformer which would create the neutral and a three phase, 4 wire setup.
 
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