Electrical grounding question

[ESP47]

My home has a combo of new and old wiring. The grounds and neutrals are bonded in the main panel.

I have a barn with a sub panel that's ran off the main panel. It's old so the feed to it is just 3 wire (two hots, neutral).

I have a new shop put up next to the barn that I'd like to install a sub panel in that's fed off the barn's sub panel. Running a new feed from the main panel would require me to trench through my driveway and would cost me thousands and thousands of dollars so it's not in the cards.

Would it be safer to just run 3 wire to the new shop from the barn and forego the ground or would running a ground rod in at the new shop and keeping the grounds and neutrals unbonded in the sub panel be safer? I feel like the former is safer than the latter but I'm unsure. This isn't going to be permitted btw.

 

[67Dart273]

I don't know. When you start using the ground as neutral, the ground may not be large enough to cheat. If you get the load unbalanced enough, there will be heavier current on the grounded conductor.

having said that, my big 240 50A meant for the welder, in the garage, is just a 3 wire connector. So everything I do is a cheat, if it was originally 4 wire. Such as the welder, etc. Not only that, with the house fire situation, not electrically caused, I am using that source to power this trailer I am existing in. It actually feeds a temp sub panel on the rear bumper, and splits off to 120V breakers. I've had no real trouble. Back in the day, that is the way it was done.

WhatEVER you do, if you do this, make sure the ground and all connections are good, that it is sized large enough, overall, but especially that the grounded conductor is up to par for carrying neutral current. And I would for darn sure make certain the subs are well grounded. Ground rods I mean.

 

[1969383S]

Is there no way to get a ground to the Barn from the Main? Typically the Neutral bar is unbonded in the subpanels and a separate bonded ground bar is added.

View attachment sub_panel.webp

 

[dadsbee]

Just drive a ground bar in at the new service, make sure the neutral/ ground strap is removed on the breaker panel. Don't forget a ground cable to any plumbing or metal piping in the building.

 

[67Dart273]

Is there no way to get a ground to the Barn from the Main? Typically the Neutral bar is unbonded in the subpanels and a separate bonded ground bar is added.

View attachment 1716458631

View attachment 1716458633

Right but he does not HAVE a separate neutral/ ground to the sub already in place

 

[1969383S]

Right but he does not HAVE a separate neutral/ ground to the sub already in place

Del the OP said 3 wires from main to the Barn, 2 hots and Neutral. Why I asked if the OP could get a Ground from the Main to the Barn!

I do not like seeing seperate ground rods at the out building's due to potentional "Differences" but Like @dadsbee says it is his best choice at this point.
If it was me, and getting a ground from my main to the Barn was going to cost Thousands of Dollars regretfully. I would Drive a Ground rod at the Barn, ensure the neutral was unbonded, add a ground block in that SP.
Run a 4 wire of the approprate size to the new shop following the same principle of floating Neutral. Add a supressor at each the Barn and the new Shop! JMO!

 

[67Dart273]

Del the OP said 3 wires from main to the Barn, 2 hots and Neutral. Why I asked if the OP could get a Ground from the Main to the Barn!

I do not like seeing seperate ground rods at the out building's due to potentional "Differences" but Like @dadsbee says it is his best choice at this point.
If it was me, and getting a ground from my main to the Barn was going to cost Thousands of Dollars regretfully. I would Drive a Ground rod at the Barn, ensure the neutral was unbonded, add a ground block in that SP.
Run a 4 wire of the approprate size to the new shop following the same principle of floating Neutral. Add a supressor at each the Barn and the new Shop! JMO!

Yeh I tend to agree. But I was thinking at the time to make sure the existing ground/ neutral is actually large enough. I've seen 2 old garages, where power was run with 2 hots and really a ground. In other words bare conductor in the jacket. And it was a bit undersized

 

[1969383S]

Yeh I tend to agree. But I was thinking at the time to make sure the existing ground/ neutral is actually large enough. I've seen 2 old garages, where power was run with 2 hots and really a ground. In other words bare conductor in the jacket. And it was a bit undersized

Well the OP needs to take the size of the wiring to the old Barn in consideration as well! Now he want's to transfer to the new Shop!

There is two loads, one must consider and calculate now. Above my general knowledge level! I would seek a Foreman Level EC help at this point if I was the OP! JMO!

 

[ESP47]

As always, thanks for the insightful help everyone.

I've been doing some research and it sounds like the second ground rod at the shop or the barn is basically a false ground with the ground and neutral unbonded at the sub panel and also path to energize my conduit in the scenario where I bond them. There seems to be no consensus on it no matter where I look other than either scenario just not being very safe.

I bought a used 240ft fish tape. I know it's a really long shot but I'm going to try and see if I can get it through the 165ft run. The run has three 90* elbows at the house and three 90* elbows at the barn. I think I'm going to dig down, open up the conduit and skip the 90s at the barn. Then I'll fish tape through the main panel toward the barn since I think logically it makes sense to have more resistance (the 90s) closer to my starting point rather than at the end of the run. Correct me if I'm wrong. I've never pulled wire through any long distance before.

I also have the option of using one of the wires to pull a new neutral and ground through but I'm worried if that doesn't work and the wires get stuck, then I'm left with no power at my barn.

Tried the vacuum method and there's no suction on the other side at all.

 

[a70duster]

Something else to consider is how is each and every breaker going to trip if a line side goes to ground. If the wire is inadequately sized the breaker won't trip.

 

[kenelder]

Your other choice is to use a 1:1 isolation transformer and only ground the secondary side plus use a ground rod. This creates a virtually new electric service for the new building and isolates it from the existing system. Not a cheap way to go but safe and meets codes.

 

[JC71340]

I would never install a sub panel without a proper neutral AND ground. I would absolutely run the ground rod for the sub panel too. Remember, if you accidentally contact the hot wire and the panel isn't properly grounded, the current will go through YOU to get to ground, probably instant death.

 

[67Dart273]

I would never install a sub panel without a proper neutral AND ground. I would absolutely run the ground rod for the sub panel too. Remember, if you accidentally contact the hot wire and the panel isn't properly grounded, the current will go through YOU to get to ground, probably instant death.

I don't understand how having a ground or not will prevent that. You could contact a hot hundreds of feet from anything, and if the ground has ANY conductivity, as around here, and if you have contact with that "the ground" you will suffer

 

[LO23M8B]

At 165 feet you should have a separate ground at the barn.

 

[67Dart273]

All this talk about inadequate is almost an argument to return to the old days, when there were 3 total wires.......the two legs, and the ground/ neutral in one wire. If that wire, that ground, which is the neutral, is carried faithfully clear through just as the hots are, then the neutral is gonna be the "good ground." Just like it is at the main.

 

[a70duster]

In order for electrical overcurrent to open a breaker it needs to return to the source.

 

[JC71340]

I don't understand how having a ground or not will prevent that. You could contact a hot hundreds of feet from anything, and if the ground has ANY conductivity, as around here, and if you have contact with that "the ground" you will suffer

You are probably right, I also thought having the separate ground path is in case of a failure on the neutral. But, again I'm no expert.

 

[marksmopars]

The purpose of the neutral wire is to carry current, the purpose of the ground wire is to provide a path for current to flow so your circuit breaker can operate properly in the event of a circuit fault, i.e. personal safety. All ground wires in a system should be tied together per electrical code, this is a safety issue. I certainly provide a ground rod at each out building to augment the grounding system, perfectly legitimate as long as all ground are bonded together.

 

[ESP47]

Thinking about it more, I'm going to need to pull the wires out and install 4 gauge. Currently has 6 gauge but the run is 120ft to the barn. The run from the barn to the shop is 60ft so I'm definitely going to need 4 gauge if I'm running off 50amp breakers for that length.

I was able to get the fish tape 90ft until it comes to a dead stop. I can also get it to go 30ft from the opposite end before it comes to a dead stop. There's either some sort of blockage there or there is a junction box or something under the ground. I'm hoping I can use the wires to pull the new wires through because I don't think fish taping is going to make it and I really don't want to dig into the yard playing guess and check on the blockage.

 

[67Dart273]

There should not be anything underground except a coupling. I would guess it has collapsed. But you pulled out the 6? Why not just use one of the 6's to pull the 4 back in as it comes out, or is it too late?

 

[ESP47]

There should not be anything underground except a coupling. I would guess it has collapsed. But you pulled out the 6? Why not just use one of the 6's to pull the 4 back in as it comes out, or is it too late?

Collapsed is a good possibility too. I never discount the work or ideas someone had in the past that seemed like a good idea at the time. There is a light pole with an outlet on it and conduit going into the ground that is perpendicular to where I believe the blockage is at. Its what had me wondering if they did some sort of funky underground junction box or something. Anyway, I'm going to fish again from the opposite end to confirm that the blockage is in the same spot from both ends. That way if I do have to get in there and make a repair, at least I'll know where to dig.

I was going to attempt using the 6's to pull the 4's as a last resort in case they get stuck and I'm left without power to the barn.

I attempted to dig near the barn in the dirt to open up the conduit so I could bypass the three 90s at the barn but I was met with a large white corrugated pipe that runs directly over where the conduit is running. Had me scratching my head because I've never seen white corrugated pipe. I'm guessing it's for some old drainage system that's no longer used but who knows.

 

[67Dart273]

So the 6's are still in? It is not uncommon for wiring to get twisted in a conduit, and cause problems with an additional fish tape. Can you move the 6's? If you don't want to stress them, you could just use them to pull a new string through.

 

[ESP47]

So the 6's are still in? It is not uncommon for wiring to get twisted in a conduit, and cause problems with an additional fish tape. Can you move the 6's? If you don't want to stress them, you could just use them to pull a new string through.

They're still in but I have six 90s total in the run. I cut into the conduit to bypass two of the 90s at my house and I'd need to cut into it to bypass the two or three 90s at the barn to even have a chance of pulling anything through there. Even a new pull string.

 

[67Dart273]

They're still in but I have six 90s total in the run. I cut into the conduit to bypass two of the 90s at my house and I'd need to cut into it to bypass the two or three 90s at the barn to even have a chance of pulling anything through there. Even a new pull string.

Yikes. Are some of them exposed so you could replace them with a "pull" 90? (The ones with the removable plate)

 

[ESP47]

Yikes. Are some of them exposed so you could replace them with a "pull" 90? (The ones with the removable plate)

I could replace one at the barn but I don't think it would help a whole lot in the configuration its in. Probably not worth typing out a few paragraphs on here to explain but I've gone over all possible scenarios in my head. I just ordered 500ft of 4 gauge so I'm going to attempt to pull it through and see what happens. I'll keep you updated.