480v 1000a power feed

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dnoethe

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I have a customer who would like me to quote a 480v 1000a power feed to a sub panel. From the sub panel we will be feeding the new equipment installed in that area. He would like me to quote this without a grounded conductor in the power feed. He has stated that none of the equipment needs a grounded conductor (neutral). Am I required to install grounded conductor for the power feed by code?
 
dnoethe said:
I have a customer who would like me to quote a 480v 1000a power feed to a sub panel. From the sub panel we will be feeding the new equipment installed in that area. He would like me to quote this without a grounded conductor in the power feed. He has stated that none of the equipment needs a grounded conductor (neutral). Am I required to install grounded conductor for the power feed by code?
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You are short enough on information that one wonders if there is a "rest of the story". However, if not, and assuming a utility fed, solidly grounded 480Y:
The neutral has to go the the first disconnect (OCP). Every thing after that has a separate neutral and Equipment Bonding Conductor. And if the neutral is not needed, don't run it. However, an EBC is still required.

edit to add: Curiousity Questions
Q1: This is a big enough job I'm surprised you don't have engineered drawings. What say your engineer of record?

Q2: This is right square in the middle of installations that can suffer horribly from arcing ground faults. What are you doing for GFP?


ice
 
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dnoethe said:
I have a customer who would like me to quote a 480v 1000a power feed to a sub panel. From the sub panel we will be feeding the new equipment installed in that area. He would like me to quote this without a grounded conductor in the power feed. He has stated that none of the equipment needs a grounded conductor (neutral). Am I required to install grounded conductor for the power feed by code?
Click to expand...

You are only required to extend the grounded conductor to the service panel. Beyond that, it is only required to be run if it is needed.
 
iceworm said:
Curiousity Questions
Q1: This is a big enough job I'm surprised you don't have engineered drawings. What say your engineer of record?
Click to expand...

I ran a job that consisted of a 13.8 to 480 volt pad mount transformer to a 3000 amp service which supplied a 1,200 amp sub panel, a few 200 feeders and 1000 kva transformer to refeed an existing 208Y/120 service.

All of this was done based on a hastily drawn one line on an 8x11 sheet of paper produced by the jobs project manager. No wire sizes, pipe sizes, pipe types etc provided that was all up to me on the job.

No engineer involved at all. Different areas have different rules and expectations.
 
petersonra said:
One would think that the GFP would be upstream somewhere.
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Yes, one would think. Then again?

iwire said:
I ran a job that consisted of a 13.8 to 480 volt pad mount transformer to a 3000 amp service which supplied a 1,200 amp sub panel, a few 200 feeders and 1000 kva transformer to refeed an existing 208Y/120 service.

All of this was done based on a hastily drawn one line on an 8x11 sheet of paper produced by the jobs project manager. No wire sizes, pipe sizes, pipe types etc provided that was all up to me on the job.

No engineer involved at all. Different areas have different rules and expectations.
Click to expand...

You're right - And there is nothing wrong with DIY engineering. I'm only mildly surprised.

Just curious - did you spec out the transformers, sub-panels, and coordination? From what I seen of your responses here - you certainly could have (truth - not being goofy)

ice
 
iceworm said:
Just curious - did you spec out the transformers, sub-panels, and coordination?
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The PM shopped the 'plan' out to a number of vendors letting them pick the equipment. It ended up being Square D throughout.

GFP was provided at the main and the feeders over 1,000 amps.

Coordination ... Hmm ... Not sure I want to say it but there was none.

When I tried to fire up the 1000 kva transformer up the factory fast and low breaker settings could not deal with it. So the only real coordination was me cranking the dials a bit.

Before you say how bad that is I will beat you too it. I know that is a hack way to go.

Most of the time we do have an engineer of record and I have refused to touch breaker settings on those jobs without specific and clear settings provided by that EE.

In one case that meant three return trips to the job due to discrepancies between the settings desired by the EE and the available settings avaible on the breakers. In that case the customer provided a pre-fab main electric room that we installed. The vendor that built and provided the electric room had substituted cheaper breakers than the EE had specified and approved.

In the mean time a large shopping center kept having large feeders trip to elevators, escalators and HVAC equipment. All I could tell them was we did not own the coordination and I was not qualified to make the settings.
 
iwire said:
... Coordination ... Hmm ... Not sure I want to say it but there was none.

When I tried to fire up the 1000 kva transformer up the factory fast and low breaker settings could not deal with it. So the only real coordination was me cranking the dials a bit.

Before you say how bad that is I will beat you too it. I know that is a hack way to go. ....
Click to expand...

I would not consider this "hack". You do what you got to do to get it running. Been more than once that I've seen a tweek with out any calculation - no time. Definitely done with experience and judgement. Oh not me - of course :angel: just others I've seen.

iwire said:
... Most of the time we do have an engineer of record and I have refused to touch breaker settings on those jobs without specific and clear settings provided by that EE.

In one case that meant three return trips to the job due to discrepancies between the settings desired by the EE and the available settings avaible on the breakers. ...
Click to expand...

This is where you grab the engineer by the ear (gently of course). Tell him to bring his slide rule and the applications manual and the oneline. Can't say I would have any trouble with that either.

This is like twice today I have agreed with you. This does not bode well. I'm taking some vitamin C and checking my temperature.

ice
 
dnoethe said:
I have a customer who would like me to quote a 480v 1000a power feed to a sub panel. From the sub panel we will be feeding the new equipment installed in that area. He would like me to quote this without a grounded conductor in the power feed. He has stated that none of the equipment needs a grounded conductor (neutral). Am I required to install grounded conductor for the power feed by code?
Click to expand...

Interesting thought. Read this post: http://forums.mikeholt.com/showthread.php?t=166242

Ask him if he might ever need a 277V load fed from that panel. Give him a price for adding the min size neutral.

Just a casual thought.
 
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