Which is the best (feasible) alternative?

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AndrewL

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Greetings,
I recently bought a house that has a detached garage. I've read a lot of posts, but I'm not able to determine what the 'best' way to handle my setup is. The building is from 1980, so I know older codes apply, but I'm more worried about making sure the wiring is safe, than compliant.

There is power buried to the garage using #10-3 UF-B wire (to be clear there is no bare copper in the bundle), not run in conduit and there are no water pipes in the garage. It is approximately 80 feet from the main service to a sub panel. The wires attach to the sub panel, 2 hots and a neutral. There is also a bus-bar for ground (bare copper) that is NOT attached to the Neutral bar or the box(not that it matters really since the box is also not grounded)

I'm fairly certain this installation is not correct, and suspect I need to do one of 2 things.

1) Add a grounding rod(s) and attach them to the ground bar, leaving it isolated from the neutrals. In my reading, I've seen mixed messages about doing this.
or
2) connect the ground bar to the neutral.


I'm aware that the best solution is to run 4 wires from the main service, but that is not feasible at this time as the wire is buried under the driveway and other hardscaping. At this point I would just like to make the existing situation as safe as possible. What should I do?
 
I think the best alternative is to consult a local licensed electrician.

I am closing this thread, in accordance with the Forum rules. This Forum is intended to assist professional electricians, inspectors, engineers, and other members of the electrical industry in the performance of their job-related tasks. However, if you are not an electrician or an electrical contractor, then we are not permitted to help you perform your own electrical installation work.


If I have misjudged the situation, if for example this project is related to your work, then send me a Private Message. If you can show me that I am wrong, and that you are a licensed electrician (or at least a licensed apprentice), then I will reopen your post, and offer an apology for the delay and inconvenience.

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After receiving a PM from the OP I am opening this thread.

I have consulted with 3 electricians, without a clear understanding of who I should hire or what I should hire them to do.

The first guy said I needed to add a grounding rod. This guy did not inspire confidence, (in an unidentifiable sort of way) and his plan for doing the work did not seem well thought out. I grant that I may be the ignorant homeowner in the situation so I went out for a second opinion

The second guy insisted only option was running a new 4 wire circuit. He seemed much more reliable than than the first guy, but he also quoted me a 8K to do the job. He said he couldn't do a grounding rod because current code doesn't allow it. We also spend a few minutes looking for an existing ground rod, because 'back in the day' it was allowed, so if I had one already, we could connect it and everything would be fine.

Since his bid is way out of my range, I went out for a 3rd bid. He gave me the same information saying he would need to run a 4 wire circuit out there, and said the same thing about the grounding rod (probably because I asked about it). He said he was too busy to bid for a small job right now - which makes me thing perhaps the 8K bid is unreasonable.

So, I started doing my own research, and turned up posts saying a grounding rod is fine, others saying it is the quickest way to die and kill everybody in the neighborhood (I'm exaggerating for effect....) I saw some suggestions that you can connect the ground to the neutral because they are connected in the main box, and thus, they find a way back to ground. If that is feasible and safe great, but just connecting things in the box seems questionable to me. None of the suggestions I've come across are things that I am looking to do myself.
Click to expand...
 
The relevant code is an exception to 250.32(B)(1), which for a new installation requires a 4-wire feed, isolated neutral, and a ground rod.

Exception No. 1: For installations made in compliance
with previous editions of this Code that permitted such
connection, the grounded conductor run with the supply to
the building or structure shall be permitted to serve as the
ground-fault return path if all of the following
requirements continue to be met:
(1) An equipment grounding conductor is not run with
the supply to the building or structure.
(2) There are no continuous metallic paths bonded to the
grounding system in each building or structure
involved.
(3) Ground-fault protection of equipment has not been
installed on the supply side of the feeder(s).

If the grounded conductor is used for grounding in
accordance with the provision of this exception, the size of
the grounded conductor shall not be smaller than the
larger of either of the following:
(1) That required by 220.61
(2) That required by 250.122
Click to expand...

You said there's no water pipe, so that's the most likely parallel metal path.

If you are not doing additional work that will cause this to need to be inspected, and you are just concerned about making it safe, then I would just bond the neutral to ground in the subpanel. That deals with the primary danger you have, which is that you don't have an effective ground-fault path to trip the breakers on circuits that might accidentally energize exposed metal parts. You can drive a ground rod, too, to make it compliant under the exception, but in my opinion this is less important from a safety standpoint. Driving a ground rod does not create an effective ground fault path.

If a local authority will be inspecting this for some reason, you'll have to confirm with them if you are allowed to use the exception or not. If there isn't a record of when the original installation was done and what code it was done under, you may have to pay for the new 4-wire feed to have it be legit.
 
If you don't need 230V out in the garage, just run 120V out to the garage. L-N-G. Pound a couple of rods out by the garage and be done with it.
 
Not sure what the OP has since he is saying 10/3 UF which is 4 wire, but apparently there is no ground or it's been cut flush, so there's only 3?? and what is the bussbar for the ground attached to?

petersonra (bob's) suggestion is probably the best with what you have.

line boring 80' (or saw cutting the driveway and repair), replacing the feeder, and making the panel compliant would not run anywhere near 8k here.
 
Thanks for the suggestions, The 4th time is the charm apparently.

Yesterday I had another electrician come out to bid, and he was able to just fix the problem on the spot. The issue turned out to be a poor upgrade done at some point (we think anyway). The wire was Essex 10-3 with ground UF-B with sunlight resistant coating (no substitute for experience - this guy knew to 'pencil rub' the wire so the indents would be readable, not just white marking on white coating) So there was a 4 with cable back to the main box.

For the curious -
When the guy was out he recognized the sub panel was practically brand new in comparison to the other fixtures in the garage. With a bit of looking around we found an old box in a junk pile in the corner that had 2 breakers but no place to attach a ground (well not a bar like the new boxes have.) The theory is that used to be the sub panel in the garage, and since it didn't have a ground bar whoever wired it just cut the ground flush. Fast forward to the junk 2 breaker box being too small, so the sub panel get an upgrade, but nobody bothers to worry about the ground - the old panel didn't have it, it was hacked off the cable so who knows what they were thinking, but they were apparently not thinking about doing it right.

Anyway, he ended up cutting the wire back a couple feet, adding a junction box, and then running a couple feet of new wire into the sub panel so everything works including the GFI outlet.

Thanks again for explaining the options for me.
 
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