3 wire feeder to separate building?

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dielectricunion

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Bloomington IN
I'm getting very confused after running into what I believe to be a totally sketchy and incorrect installation of a subpanel on a residential property.

100 amp subpanel in separate "cabana" feeding mostly in ground pool loads, #2 AL triplex (3 wire) direct buried, grounds and neutrals separated at the subpanel. Electrician says it is grounded because he drove a ground rod.

Is this acceptable? My understanding of the code says no. My understanding of the way electrical systems works says no. I've found several things "online" that say I am wrong, including "ask the electrician".

Installing a Sub Panel for a Detached Building

Do I need to run a ground wire for a 200 amp sub panel that is 200 feet away from the main panel? Grounding a Remote Sub Panel at a Detached Building.
ask-the-electrician.com


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Thank you- I was starting to get paranoid that somehow I'm completely out of line and wrong in calling out this install to the homeowner as a safety/code issue. The electrician who just installed the whole thing says he always does this on pools and even if there was an inspection (no permits) they would definitely pass...


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Look at 250.32(B).

250.32
(B) Grounded Systems.
(1) Supplied by a Feeder or Branch Circuit. An equipment grounding conductor, as described in 250.118, shall be run with the supply conductors and be connected to the building or structure disconnecting means and to the grounding electrode(s). The equipment grounding conductor shall be used for grounding or bonding of equipment, structures, or frames required to be grounded or bonded. The equipment grounding conductor shall be sized in accordance with 250.122. Any installed grounded conductor shall not be connected to the equipment grounding conductor or to the grounding electrode(s).
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Not incorrectly bonding the grounds and neutrals is even more dangerous than bonding them would be.

Ask him what will happen if a hot wire accidentally touches what should be a grounded surface?
Hint: "The breaker will trip" is NOT correct; the earth is not capable of passing enough current.

dielectricunion said:
Thank you- I was starting to get paranoid that somehow I'm completely out of line and wrong in calling out this install to the homeowner as a safety/code issue.
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You're correct, he's wrong.

The electrician who just installed the whole thing says he always does this on pools and even if there was an inspection (no permits) they would definitely pass...
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Have him prove that.
 
The question now become, how does a HO convince the hired "electrician" that his installation is not code compliant...
 
sw_ross said:
The question now become, how does a HO convince the hired "electrician" that his installation is not code compliant...
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By insisting that a permit and inspection be included, or hire someone else.

When he said his work would pass an inspection, I would say, "You'll get paid when it does."
 
We recommended abandoning the buried SEU triplex and running a new 2" conduit with 4 wire but basically said we'd prefer not to be involved in that pool situation. They hired a 3rd electrical contractor to finish that up. They agreed that it needed a ground but said there's no reason it needed to be in conduit.

Their fix was running a #6 solid bare wire all the way from the cabana sub panel with the feeder. This was bare copper buried under ground for over 60 feet. Isn't that going to degrade? I know it's common to have a bare copper GEC running a short length around ground level to the rod but this seems lime it should have been insulated single conductor rated for direct burial.

Maybe I should be happy we didn't have to deal with it and stop criticizing everyone!


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You can run a solid copper conductor for the EGC but it must be in the same trench as the feeder conductors. Bare copper conductors are permitted to the buried in the earth. So for this installation you would need to dig up the entire run of the 3 wire feeder and lay the EGC in the same trench for it to be code complaint. You also said a 100 amp sub-panel with #2 aluminum, #2 Al is only good for 90 amps.

300.5
(I) Conductors of the Same Circuit. All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench.
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The electrode in the ground does 'ground' the subpanel. However the soil is not an effective fault current path.

If this subpanel had ground and neutral bonded (which _is_ allowed in some very limited situations) then the neutral would provide the fault current path.

An EGC must be run with the circuit it protects, so at a minimum the triplex needs to be dug up to install the required and missing EGC. At which point I personally would go with the conduit install.

#2 Al is NEC compliant for a 100A residential service, but not a 100A feeder. Lots of people will miss/pass this one and allow #2 for a 100A feeder in a residential situation. The one situation where this is compliant if it is a 100A feeder coming off of a 100A service, since the feeder conductors do not need to be larger than the service conductors.

-Jon
 
This site is run by a guy who is running somewhat of a miseducation business. He specifically instructs people to do what I saw on this job. He claims to be a licensed electrician and educator for 38 years. I emailed him telling him he needs to remove that ASAP

Installing a Sub Panel for a Detached Building

Do I need to run a ground wire for a 200 amp sub panel that is 200 feet away from the main panel? Grounding a Remote Sub Panel at a Detached Building.
ask-the-electrician.com


Sent from my iPhone using Tapatalk
 
winnie said:
The electrode in the ground does 'ground' the subpanel. However the soil is not an effective fault current path.

If this subpanel had ground and neutral bonded (which _is_ allowed in some very limited situations) then the neutral would provide the fault current path.

An EGC must be run with the circuit it protects, so at a minimum the triplex needs to be dug up to install the required and missing EGC. At which point I personally would go with the conduit install.

#2 Al is NEC compliant for a 100A residential service, but not a 100A feeder. Lots of people will miss/pass this one and allow #2 for a 100A feeder in a residential situation. The one situation where this is compliant if it is a 100A feeder coming off of a 100A service, since the feeder conductors do not need to be larger than the service conductors.

-Jon
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If it is a feeder carrying the entire load of a dwelling #2 Aluminum is acceptable.

Sounds like that probably not the case with OP but if his separate building met the definition of a dwelling unit it could apply.
 
dielectricunion said:
We recommended abandoning the buried SEU triplex
Click to expand...

If this is in fact a direct buried SEU cable, it is completely wrong. There is no fix, no adding a ground, no bonding the neutral/ground. The only repair is to replace the SEU cable with a different wiring method. This cable type cannot be direct buried or ran in an underground conduit. The bare neutral will corrode and turn into white chalk at some point.
 
dielectricunion said:
This site is run by a guy who is running somewhat of a miseducation business. He specifically instructs people to do what I saw on this job. He claims to be a licensed electrician and educator for 38 years. I emailed him telling him he needs to remove that ASAP
Click to expand...
Obviously he's incorrect about not running an EGC with the feeder and then not bonding the neutral which would create a dangerous installation.
 
winnie said:
The electrode in the ground does 'ground' the subpanel. However the soil is not an effective fault current path.

If this subpanel had ground and neutral bonded (which _is_ allowed in some very limited situations) then the neutral would provide the fault current path.

An EGC must be run with the circuit it protects, so at a minimum the triplex needs to be dug up to install the required and missing EGC. At which point I personally would go with the conduit install.

#2 Al is NEC compliant for a 100A residential service, but not a 100A feeder. Lots of people will miss/pass this one and allow #2 for a 100A feeder in a residential situation. The one situation where this is compliant if it is a 100A feeder coming off of a 100A service, since the feeder conductors do not need to be larger than the service conductors.

-Jon
Click to expand...
 
I know this is a old post but I really never understood that. I know that if a #2 AL is feeding a 100 amp sub panel that supplies the entire load of a dwelling it's acceptable because of the diversity. And if you feed a 100 amp sub panel from a main 100 amp panel then the feeders doesn't need to be any larger than the service conductors. But you still could possibly have 99 amps on the #2 AL feeding the sub panel.
 
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