50 amp, 240 volt hookup without equipment ground

A panel in an RV is no different than a sub-panel in a house. It requires a ground conductor back to the main panel where it is grounded. A GFCI recept. or breaker cannot be substituted for the lack of a ground conductor to a sub-panel - no exceptions except in old houses with existing 2-wire recepts. with no ground wire. The ground connection in downstream/sub panels cannot be bonded to ground and the ground conductor needs to be correctly sized. It is unsafe to have an RV ungrounded.

The existing work sounds like a total mess. It's hard to give good advice from a distance and there could be other related issues too that should be dealt with. Short of completely redoing it, the easiest solution sounds like converting it to 30 amps (120 volts) and re-identifying the conductors with the correct color tape per NEC requirements.

Ground requirement for RVs (and RV Parks) is covered by art. 551 in the NEC. For some reason I can't find the free online 2104 NEC otherwise I'd post a link to art. 551. For accurate advice, the Mike Holt electrical forum is good. If you don't have a good grasp on doing electrical work and don't know the code requirements, I'd hire an electrician.

Although I have seen it done on many post-WWII houses, my current house built in the '70's has the sub-panel setup I described. The main panel on the side of the house has the 240v services - A/C, Range, HW - while there is a separate sub-panel inside the house with all the 120v services on it. There is no ground extended from the Main to the Sub. It's just the way it was done until a couple of decades after WWII. Not correct these days and not as safe as a fully grounded system.

mikeh449 wrote:
gfci needs ground also

nope it does NOT in fact GFI work well with old houses w/o grounded recepticals. ALL a GFI does is detect a current imbalance between hot and neutral. It NEVER looks at ground current.

Again I will say that a GFI is the only safe and to code way to put a grounded outlet on a non grounded system- as said, it must be labeled no Equipment ground, but it does not need a ground, and will protect anyone from shock even without an earth ground. Bonding the ground to the neutral is wrong and dangerous, adding a ground rod is probably OK, but getting a good ground is sometimes problematic, depending on the soil. Here in Florida a 10 foot rod is going in to the ground water.

At first I was not sure about a 240 volt gfi, but they are labeled 120/240 volts, indicating they will safely trip using 120 volt loads.

DougE wrote:
Way back in the dark ages, houses had a main panel and sub panels. The main panel was grounded but the sub panels were not. The neutral and the ground were common (connected together) at the main panel. Extending both the neutral and ground to the final use is kind of a belt and suspenders approach adopted for more recent electrical codes (if there is an issue with the neutral wire you still have the protection of the ground wire). (Electrical gurus can explain this better.) In older houses without grounding systems I often (for my own use), replace two prong receptacles with three prong receptacles and tie the ground to the neutral similar to time2roll's suggestion.

Subpanels are not just a thing from the dark ages, but are very much used today if conditions dictate. One typical example might be for a shop where one would like to have ready access to breakers that trip. And yes, a subpanel must have isolated neutral and ground busses.

The original poster apparently has two main panels, which is not an unusual setup in some parts of the country. My own house has two 100A main panels next to each other, originally one for electric heat and one for the rest of the circuits in the house.

Installing a grounded outlet on a two-wire circuit and bonding the ground to the neutral at the outlet is a dangerous setup, particularly in the event of a fault in the neutral line feeding the outlet, and definitely is not permitted by the NEC. It is permitted (and a lot safer) to have a three prong outlet if there is a GFCI protecting it, even if it's not grounded. There is a labeling requirement in that case indicating something to the effect that it's GFCI protected but not grounded. The ground prong would not be bonded to neutral. Of course, one may also run new wires and have a real ground.

Multiple positions on this.. but here is mine.
Though the CODE for wiring says "Neutral and ground are bonded at the service entrance" (Main distribution box) if you go to most any RV park you will find that often each box has its very own ground rod. So grounding at the site is ... Not going to cause problems.

Drilling through a brick wall is also very easy.. I have a hammer drill and masonry bits They go through a brick wall like it was soft Pine.

Now we get to the tricky part.... In the parks where I notice each box has a ground it's a single ground rod.. Code now days is 2 ground rods. with a minimum distance between them, 10 foot.. I won't advise that is the term "overkill" applies. but Well....

YOu do have options.

Finally, the ground is a safety, ideally it never does anyhting but sit there.. In practice, you may find the "Skin" of your RV hanging in there at around 60 volts, amost no current ability (60 very high impedance volts) but still 60 volts without a ground.

I can also ground the RV chassis on my rig if needed (Do it boondocking for other reasons).

Way back in the dark ages, houses had a main panel and sub panels. The main panel was grounded but the sub panels were not. The neutral and the ground were common (connected together) at the main panel. Extending both the neutral and ground to the final use is kind of a belt and suspenders approach adopted for more recent electrical codes (if there is an issue with the neutral wire you still have the protection of the ground wire). (Electrical gurus can explain this better.) In older houses without grounding systems I often (for my own use), replace two prong receptacles with three prong receptacles and tie the ground to the neutral similar to time2roll's suggestion.

This dwelling has, what appears to be, two parallel 200 amp boxes. It is about 4500 sq. ft.

The wiring, somehow, passed inspection when my son bought the house, last year. As someone said, this modification was done with, what appears to be, a piece of a 30 amp RV extension cord.

I have a 50 foot RV extension, purchased for use here only. For now, I will change this over to a 30 amp setup, using the existing cable until I can get it repaired to use the 50 amp setup. Summers, here often require two air conditioners and there is no shade,

Thanks for posting, Happycamper. We can all learn from professionals and retired guys have a lifetime of experience under their belt.

To me, it sounds like the OP will have some sorting out because of the previous owner's work. I experienced the same when I bought my own old house.

Try this: My old dwelling had knob and tube for most of it's life. The previous owner had installed a more modern load center and pulled some circuits with NM-B (Romex) but the lights and some receptacles were still powered by knob and tube, dropped from the attic. When I pulled the paneling from the attic stairwell, I found an old disconnect box used as a junction box. A single cloth insulated wire was led into the box and the cover held that wire, crimped by the paneling that was installed over the box. It's a wonder that there was no fire.

I'm sure Happycamper has some stories about what he's found, also. I'm a Residential Contractor and have found really substandard electrical, plumbing, and mechanical issues.

If the wiring system is wired with IMC (intermediate metal conduit) or RMC (rigid metal conduit) whether buried underground or overhead with approved hangers ground wire or bonding wire is not required as long as the conduit run is continuous without any transition from metal to PVC conduit or Romex.

By continuous,it includes any pullboxes or junction boxes complete with locknuts and pigtail tabs. Industrial and commercial wiring are all done this way. BX or armored cable have also built-in grounding capability. This is what inspectors look for.

OP mentioned that this is a lakefront property. Some inspection agency having jurisdiction has strict regulation when building homes near water just like swimming pools.

To OP, check if the above applies in your situation. Then you decide the appropriateness of any correction needed.

Lastly, you mentioned that there is a subpanel where this thing is. If in fact it is you can't drive a separate ground rod. It should only be installed at the main panel.

For what it's worth, I'm a retired electrical contractor.