Does adding a ground rod fix a campground hot-skin voltage?

No, it does not! And here's why...

Here’s a comment on my post Grounding Part 1.

Hi Mike,

We are at a well maintained campground which recently upgraded all the campground electrical including pedestals. My neighbor had an issue with his hw and was trying to figure out, I was helping him with checking for power to hw tank and with my ncv realized he had a hot skin situation. We went through the breakers and found the circuit which I told him to leave off until fixed. I gave him this newsletter info to subscribe to.

He got an electrician in next day and everything checked out on the rv and he traced the problem to the pedestal, ground issue. The electrician checked the ground at the main distribution panel and ended up putting a ground in at the pedestal which resolved the issue. Seems this has happened to other pedestals here as well. The rv owner had no idea of the dangers of hot skin, neither did Park officials.

So 2 things, thank you for sharing your expertise, I read all your emails and have gained valuable knowledge and you have gained another subscriber. Second is adding the ground to the pedestal seems to have fixed the situation but is it the proper fix. Thanks Allan C.

Everyone,

Adding a ground rod to pedestal DOES NOT correct the problem of a missing or high-resistance EGC ground connection back to the main circuit breaker panel. That’s because the job of the ground wire in your RV is to provide a low-resistance path for any short circuit to have enough fault current to quickly trip (clear) the circuit breaker. And a ground rod is really only there to provide a path for lighting. Here’s the test/demonstration I did in my FunkWorks Lab a few years ago.

The test setup

I just pounded an 8-ft grounding rod into the dirt right behind my lab and connected a big battery clamp on it. This is a very dangerous test that could kill you, so don’t try this demonstration yourself!

I then hooked the test wire to an Edison plug which put 119-volts into the ground rod while I monitored the voltage and current. As you can see, it pulled 1.33 amperes of current at 119 volts.

What does this mean?

If we divide volts / amps it gives us resistance. So 119 volts / 1.33 amps = 89.4 ohms. That shows that even a direct short circuit from a hot-wire in your RV to its chassis would not create enough fault current in a ground rod alone to trip a 20 or 30-amp circuit breaker. It needs a low-impedance conductor path back to the main circuit breaker panel’s neutral bond that will create enough current to trip the circuit breaker.

Why did the ground rod seem to fix the OP’s problem.

There wasn’t a short circuit with a lot of potential fault current in Allan’s RV. There’s always small leakeage currents in anything plugged into a voltage source. But those are typically on a few mA (milliamperes, maybe 0.003 amps). A grounding rod can easily provide a path to ground for those small currents. But a high-current fault such as a water heater element or bare wire contacting the chassis will provide too much current for the ground rod to get rid of, so the RV will develop a high-current hot-skin voltage that can be deadly.

How to test for ground

More on this later, but I’ve been developing a test procedure for campground pedestals using an Extech CT70 Circuit Load Tester that will confirm ground bond continuity. Watch for a deep dive into this new test procedure in a few months.

In the meantime read this…

Let’s play safe out there… Mike