Wiring A 30amp RV Outlet - Ground & Neutral

[Kampfirekid]

I wired up a 30amp plug in my barn this weekend to power the travel trailer when it’s in the driveway. My barn is wired with a 100amp service breaker cabinet off the house main service, which was installed 18 years ago by a certified electrician, and inspected by the County Building Department.
Question I have is related to ground and the neutral for the plug. The terminations on the plug are done as required,, but at the panel, the ground and neutral bus is bonded together. Is this a no-no for RV services.
I terminated the neutral wire on the neutral buss on the same side as the breaker, and then terminated the ground to the same buss where the ground wire from the house service terminates... which is on the neutral buss on the other side of the panel. Is this correct? Being a single pole 30A breaker, the 120V to the plug is a no-brainer, but is the shared ground/neutral an issue?
Thanks for your help.

[Kampfirekid]

After further research, the neutrals in the barn sub panel are NOT bonded to the sub panel box with the single green bonding screw. I was in error, as I saw a green screw at the top of each neutral terminal bar to the cross bar that ties them together. In the electrical world, green means “ground”. I ASSumed those screws bonded the neutral to the cabinet.

So, the barn sub panel is not independently grounded to the earth with a ground rod. There is NO ground terminal strip in the barn sub panel. The ground from the house to the barn sub panel lands on a neutral bar in the sub panel, as does the ground wire from the house, as well. Do, in any event, the neutral and ground in the barn sub panel are only tied back to the house main panel.

As I see it, will need to install a ground strip in the barn sub panel, a #6 ground wire to a ground rod outside the barn, and terminate the ground from the house panel to the ground strip in the sub panel. Then, all grounds in the sub panel, which there is only one for the RV plug, will terminate to the ground strip. I have no other grounds in the sub panel as I used EMT, which grounds back to the sub panel. - which is a better reason to get the sub panel independently grounded.

Last plan is to install a ground stud on the metal siding of the barn and wire it to the ground strip in the barn sub panel to bond it all together..

[Kampfirekid]

time2roll wrote:
So 3 wire 240v split phase.... not 4 wire. Dang I would be hoping the conduit is large enough to pull a ground wire. Good luck.

There ARE four wires. Red (110V), Black (110V), White (neutral), and ground. My point is there is no ground wire from the barn sub panel to the earth... only the wire between the main house panel (neutral buss) and the barn sub panel neutral bus. Looks like what needs to happen is:

1) Removal of the bonding screw in the sub panel
2) Installation of a ground terminal strip In sub panel - bond to sub panel metal case
3) Installation of a ground rod at the sub panel
4) Installation of ground cable from ground strip in sub panel to ground rod
5) Reterminate any grounds (like this 30A RV outlet) on the ground terminal strip.

All neutrals in sub panel then will go back to the house main panel, but barn circuit grounds will be separated and go to earth outside the barn (to earth).

[time2roll]

So 3 wire 240v split phase.... not 4 wire. Dang I would be hoping the conduit is large enough to pull a ground wire. Good luck.

[Kampfirekid]

I now verified the bonding screw is installed in the barns sub panel to bond the neutral to the Square D Barn service sub panel. However, the sub panel isn’t grounded, per say, as there is no wire to ground (rod). The conduit from the house to the barn sub panel is EMT, but it actually breaks before going underground and goes to PVC. That said, there actually is NO ground in the sub panel because the sub panel is NOT grounded. There is no ground strip in the sub panel with a wire heading out to the ground and a ground rod. So, the electrician used the neutral back to the house as the path to ground.

[Kampfirekid]

rhochnadel wrote:
Eighteen years ago National Electric Code required the neutral bus and ground bus be separate, usually a single screw between the two buses would have to be installed to bond the two busses. Your barn panel should have a separate ground bus. Only the house panel should be bonded together. Talk to your electrician, ask him to correct it. You will be glad you did.

Thanks for your help. I have a friend who is a retired electrician and stays up to date and certified in the most current NEC. I reached out to him.
I looked at the sub panel In the barn. Clearly there are single screws at the top of each neutral buss bonding the two together with a strap across the top. One is not dedicated as a ground terminal strip. In fact, the large lug installed on the left neutral buss is the same one the ground wire from the house panel is terminated to.
Everything I read says sub panels need to be grounded separately. There is no separate wire to a ground rod in the sub panel. Looks like an easy fix, but I see no provisions on the panel for grounding (I.e. a ground stud or terminal strip). I can’t figure out how this could have passed inspections Further review seems this work might have been done about 16 years ago. Regardless, it is pretty obvious, unless one of the neutral busses is grounded to the cabinet and I can’t see it.

[CA_Traveler]

theoldwizard1 wrote:

CA Traveler wrote:
It's OK. RVs don't bond utility power ground and neutral. That's done at the main panel and in your case the barn. The ground is a safety wire and bonding at the barn is consider safe.

WAS considered safe !

This was common practice until about 10 years ago (?) when the National Electric Code (NEC) changed and there can only be on bond in a system and it must be at the first disconnect. After that, 4 wires must be run to each distribution/breaker panel.

Thanks for the update.

[rhochnadel]

Eighteen years ago National Electric Code required the neutral bus and ground bus be separate, usually a single screw between the two buses would have to be installed to bond the two busses. Your barn panel should have a separate ground bus. Only the house panel should be bonded together. Talk to your electrician, ask him to correct it. You will be glad you did.

[Kampfirekid]

To clarify, there are FOUR wires between the Main house 200A panel and the 100A barn panel. BOTH panels were installed at the same time about 18 years ago as I upgraded the house to a 200A panel. All was inspected and approved by the County Building Department.
Both legs come into the barn panel to provide 220V. Then a same-size neutral comes in and is connected to the neutral buss, which has a plate connecting both neutral terminal strips on each side of the vertical runs of breakers. Then, the smaller ground wire is connected to the bottom of the left neutral terminal strip, right where other neutrals are terminated from a couple 110V receptacle circuits.
The house built in 1967 was run in romex. About every run is a home run back to the house panel. I ran all 110V in the barn in EMT. I’m having a hard time believing both the electrician and the inspector were wrong, but hey, I’d rather be safe than sorry.

[time2roll]

theoldwizard1 wrote:

time2roll wrote:
At this point I believe it is best to separate the grounds to an independent bus in the barn subpanel.

If the installation was to code before the code changed your fine AS IS !

If you do not have 4 wires (2 hots, neutral and ground) going to the barn, disconnecting that bond would be dangerous !

I stand by my recommendation to make it right.
I would not have it wrong on my property.
Just because you are entitled to avoid the new safety rules does not make it a best practice.
JMHO

[theoldwizard1]

CA Traveler wrote:
Interesting that earth grounding or not of a remote panel seems to vary. Local codes might be different.

One bond has been NEC "law" for several years now !

Sjm9911 wrote:
It depends also on when the equipment was installed. Years ago panels only had one ground bar for both neutral and ground wires. It was the only way to do it. The ground is basically a back up to the neutral anyway.

From a schematic diagram you are correct, but there is more to it than that.

The original purpose for a ground was because if the hot accidentally shorted to the housing of an appliance any human who touched the case of the appliance could complete the path to ground and be electrocuted.

This is still true, but most residential appliances have plastic housings. Now the primary purpose of the ground single bond has more to do with lightening strikes.

[Mike134]

theoldwizard1 wrote:

CA Traveler wrote:
It's OK. RVs don't bond utility power ground and neutral. That's done at the main panel and in your case the barn. The ground is a safety wire and bonding at the barn is consider safe.

WAS considered safe !

This was common practice until about 10 years ago (?) when the National Electric Code (NEC) changed and there can only be on bond in a system and it must be at the first disconnect. After that, 4 wires must be run to each distribution/breaker panel.

You bring up a good point, for the longest time the neutral was used to ground the metal frame of an electric dryer/electric stoves so you only needed 3 wires, now both devices need 4 wires.

[theoldwizard1]

time2roll wrote:
At this point I believe it is best to separate the grounds to an independent bus in the barn subpanel.

If the installation was to code before the code changed your fine AS IS !

If you do not have 4 wires (2 hots, neutral and ground) going to the barn, disconnecting that bond would be dangerous !

[theoldwizard1]

CA Traveler wrote:
It's OK. RVs don't bond utility power ground and neutral. That's done at the main panel and in your case the barn. The ground is a safety wire and bonding at the barn is consider safe.

WAS considered safe !

This was common practice until about 10 years ago (?) when the National Electric Code (NEC) changed and there can only be on bond in a system and it must be at the first disconnect. After that, 4 wires must be run to each distribution/breaker panel.

[time2roll]

At this point I believe it is best to separate the grounds to an independent bus in the barn subpanel.
Possibly discuss this with another electrician to come out and do the proper work.

Post some pictures if it seems unclear on how to proceed.