existing outbuildings are ungrounded

[malachi constant]

I'm the signing engineer on a project that is under construction - existing golf course clubhouse will be torn down and the new one is nearing completion. The grounds contain a couple outbuildings - from what I understand they are basically sheds. I noted in the contract documents to intercept the circuits feeding these outbuildings and refeed from a breaker in the new clubhouse. Unfortunately we recently discovered the existing outbuilding feeders do not have a ground wire pulled with them. That's about all I know, and even then it's third-hand information. I am trying to get more information.

In the meantime I heard that the electrical contractor opined at a recent construction meeting that there might be a loophole in the code that allows buildings without plumbing to be ungrounded. As far as I know that is a ridiculous proposition, but I've been wrong enough in the past I figure it's worth running by you guys. Assuming there is no such loophole, I assume the best option is to rip up the feeder all the way back to outbuilding and replace with one containing a ground.

Like I said, I don't have all the information yet...might be a little too quick to say what the best option is or isn't until I know more...

 

[kwired]

Is there grounded neutral conductor or just ungrounded conductors only? If you have ungrounded conductors only you may have a problem.

You used to be able to run separate buildings just like we do services until 2008 NEC (maybe 2005 but I think 2008), run ungrounded conductors and neutral (no separate equipment ground) and install a bonding jumper and grounding electrode system. This was not permitted if there were other conductive paths between the two buildings that could be bonded to electrical system and therefore allow parallel neutral current to travel over those other paths.

250.32(B)(1) exception still allows existing installations to remain that way if they were installed correctly at time of installation.

Another option is to put a transformer (separately derived system) at each building and then you don't need a neutral with the feeder but you still need an equipment grounding conductor with the feeder.

 

[Cow]

Sounds like something that's up to your AHJ. If you're not extending it, just digging it up and swinging it over so it can be fed from a different panel, I wouldn't think twice about doing it. This is assuming there are no other metallic path's between the buildings that may have been added since it was wired originally.

Not a big deal at all, there must be hundreds of thousands of these feeders still in existance.

 

[tom baker]

You have ungrounded buildings on the grounds?
Sorry.
We get confused on grounding and bonding due to improper use of terms.
And the code has changed.
It was allowed to use the neutral for bonding at the seperate building, but a a grounding electrode system was aways required.
Today we can no longer "reground" the neutral.

And thanks for asking. I like your attitude.

 

[kwired]

Today we can no longer "reground" the neutral.

For new installations this is true.

From my previous post:

250.32(B)(1) exception still allows existing installations to remain that way if they were installed correctly at time of installation.

OP may be able to leave it as it was if there is no parallel paths for neutral current to flow between buildings or structures. If enough of the feeder is torn up or being changed/moved or whatever then the AHJ may consider it to be new and want separate grounded and grounding conductors.

 

[malachi constant]

Thanks all. A little more information:
* Original feeder is direct buried (i.e. not in conduit) and contains two hots and a fully-sized neutral.
* The outbuilding is about 150' away from where the new pull box is (and the pull box is near where the old utility meter was). There is about 50' of new feeder from pull box to breaker panel in new building.
* For what it's worth I have in my notes for this to get refed from a 50A/2P breaker but can't for the life of me remember where I got that from. I don't think the Owner provided it, nor do I think I field verified it.
* The outbuilding is used for cleaning golf balls. They carry buckets of water up there, not plumbed.
* There are no other ground paths connecting the buildings. No plumbing. Was a phone line running to the building but that was interrupted as part of this construction and rather than reroute the Owner said to abandon it and they'll just use their cell phones.
* Inspector will not allow 250.32(B)(1) exception. He keyed in on "for installations made in compliance with previous editions of this Code that permitted such connection" and basically said the old installation has been sufficiently changed by taking it off the utility and extending it to a breaker, so we don't have an "installation that was previously in compliance", because we don't have that installation any more. I get what he's saying just enough to not argue the point.

So...I'm headed out for a week's vacation in four hours. (It is 8am central on Friday right now.) I'm all set to issue a PR that says something along the lines of "provide equipment ground wire to outbuilding as required by 250.32(B)(1) and electrical inspector, field-coordinate preferred routing option with Construction Manger, Architect and Owner."

Before I send that out are there any other solutions? I hardly ever deal with single phase transformers, but with three phase delta:wye you don't need to run a neutral to the primary side. Is it feasible to install a single phase transformer of some sort that: 1) doesn't change the voltage (like is a 230V to 230V isolation transformer?) and 2) doesn't require a neutral, so the neutral to the outbuilding could be used as an equipment ground? Am I just making stuff up here that has no basis in reality?

Thanks again for all your help! This is a great forum.

 

[kwired]

Thanks all. A little more information:
* Original feeder is direct buried (i.e. not in conduit) and contains two hots and a fully-sized neutral.
* The outbuilding is about 150' away from where the new pull box is (and the pull box is near where the old utility meter was). There is about 50' of new feeder from pull box to breaker panel in new building.
* For what it's worth I have in my notes for this to get refed from a 50A/2P breaker but can't for the life of me remember where I got that from. I don't think the Owner provided it, nor do I think I field verified it.
* The outbuilding is used for cleaning golf balls. They carry buckets of water up there, not plumbed.
* There are no other ground paths connecting the buildings. No plumbing. Was a phone line running to the building but that was interrupted as part of this construction and rather than reroute the Owner said to abandon it and they'll just use their cell phones.
* Inspector will not allow 250.32(B)(1) exception. He keyed in on "for installations made in compliance with previous editions of this Code that permitted such connection" and basically said the old installation has been sufficiently changed by taking it off the utility and extending it to a breaker, so we don't have an "installation that was previously in compliance", because we don't have that installation any more. I get what he's saying just enough to not argue the point.

So...I'm headed out for a week's vacation in four hours. (It is 8am central on Friday right now.) I'm all set to issue a PR that says something along the lines of "provide equipment ground wire to outbuilding as required by 250.32(B)(1) and electrical inspector, field-coordinate preferred routing option with Construction Manger, Architect and Owner."

Before I send that out are there any other solutions? I hardly ever deal with single phase transformers, but with three phase delta:wye you don't need to run a neutral to the primary side. Is it feasible to install a single phase transformer of some sort that: 1) doesn't change the voltage (like is a 230V to 230V isolation transformer?) and 2) doesn't require a neutral, so the neutral to the outbuilding could be used as an equipment ground? Am I just making stuff up here that has no basis in reality?

Thanks again for all your help! This is a great forum.

The transformer idea was exactly what I was talking about at end of post #2. 240 volt in (plus equipment ground for the enclosure(s) and 120/240 out - separately derived system.

You will need to figure out if cost of transformer is worth it vs a new feed with proper conductors or adding an additional conductor if possible. If you add another conductor remember it is supposed to be in close proximity to the other conductors of the same circuit according to 300.3(B).

 

[George Stolz]

See if your load will permit using the existing conductors as phase, neutral, EGC.