# Who needs grounding anyway?



## Discophive (Mar 11, 2011)

Today at a water plant I ran across a 200amp 3phase 480volt service disconnect provided by the utility company without a grounded conductor. The service disconnect supplies several raw water pumps and other equipment with three phase conductors ran underground in PVC conduit without an equipment grounding conductor. The feeders terminate inside a junction box with all the separate equipment disconnects tapped off. This system was installed a few years back by who knows who but my question(s) is: (a) what exception exists to disregard a grounded conductor ran with the phase conductors (b) how can this installation be considered code compliant (c) how to best protect operating personnel in case of a fault until code compliant corrections are made.

Since the Service disconnect is over 600' from the raw water pump station, is ran underground in 2" pvc conduit through a road composed of 12" boulders, does not benefit from main disconnect at the separate structure and will be a significant effort in time and material to correct, this small town water utility will be reluctant to approve a major rework of this installation.


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## bereawouldworker (Dec 10, 2010)

this makes me wonder: if you have a grounded delta system, do you neccessarily need an egc?


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## erics37 (May 7, 2009)

Maybe it's a 480V ungrounded system. If they don't need a neutral for anything then what's the sense in the utility providing one?










They should, however, have an EGC system and a ground fault detector setup of some sort.


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## erics37 (May 7, 2009)

bereawouldworker said:


> this makes me wonder: if you have a grounded delta system, do you neccessarily need an egc?


Do you mean ungrounded delta system? If so...

 You betcha!

If you have a ground fault on an ungrounded system with no grounded conductor then there's no way for the fault current to return to the source, so it just energizes everything up to that phase potential. You still have to EGC and bond everything and all that, there's just no low-impedance return path to the source. So you have to have a ground fault detection system set up to indicate when a ground fault occurs so you can fix it.


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## Rockyd (Apr 22, 2007)

Getting high up on a pedestal so I'll be an easy target here...

Going to first say 250.24(C) *Grounded conductor Brought to Service Equipment*.

Next, who did the original install? And...and are they liable if it doesn't meet minimum? Who passed the job off on the inspection?

Next part - does 250.21 Can all the items be met? May be the route they thought they were going?

Before to much thumping starts,:hammer: I'm Electrical quarterbacking from at least 2500 miles from you....


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## Big John (May 23, 2010)

erics37 said:


> ...If you have a ground fault on an ungrounded system with no grounded conductor then there's no way for the fault current to return to the source, so it just energizes everything up to that phase potential....


 I think a better way to say it would be that it brings that phase down to earth potential. Yes, they're both the same potential, but with a solid ground fault, the phase potential relative to earth is zero volts and you shouldn't have much touch potential to worry about.

The real danger is that the two ungrounded phases are now 600V to ground.  A shock like that can easily make a guy into plant food.

-John


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## bereawouldworker (Dec 10, 2010)

erics37 said:


> Do you mean ungrounded delta system? If so...
> 
> You betcha!
> 
> If you have a ground fault on an ungrounded system with no grounded conductor then there's no way for the fault current to return to the source, so it just energizes everything up to that phase potential. You still have to EGC and bond everything and all that, there's just no low-impedance return path to the source. So you have to have a ground fault detection system set up to indicate when a ground fault occurs so you can fix it.


nope, i meant grounded.


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## Discophive (Mar 11, 2011)

Rockyd said:


> Getting high up on a pedestal so I'll be an easy target here...
> 
> Going to first say 250.24(C) *Grounded conductor Brought to Service Equipment*.
> 
> ...


Very helpful thank you for pointing to 250.21. Unfortunately, this Article does not provide any cover for judging this as a code compliant installation but at least I can point there when inevitably asked why on Gods green earth 600' of underground feeders where supplied without at EGC. Honestly I don't know who the installer was or what they were thinking except that maybe their ground rod for the pump panels was going to save someones life. 

I don't know of any acceptable means of bringing this up to code except to run an EGC from the service disconnect to the pumps but if anyone has any ideas my customer will be all ears.


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## Big John (May 23, 2010)

bereawouldworker said:


> nope, i meant grounded.


 Any grounded system always needs an EGC. 

Otherwise what Eric was saying is true: There won't be an easy return path, and things can get energized to phase voltage relative to the earth. Real good recipe for electrocution.

-John


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## don_resqcapt19 (Jul 18, 2010)

Big John said:


> Any grounded system always needs an EGC. ...


 The grounding and bonding rules are identical for grounded and ungrounded systems, with the exception that you don't use a main or system bonding jumper for an ungrounded system. Both grounded and ungrounded systems require grounding electriodes, grounding electrode conductors and EGCs.


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