Can Hot-Skin Voltage Happen Without Being Plugged Into Power (Part 2)
Yes, you can get a shock from your RV even when it's not plugged into shore power!
Here’s Part 2 of my article on hot-skin voltage causes
Dear Mike,
We have recently purchased a new travel trailer, and I have noticed a small shock on different occasions while touching the frame. I understand the hot skin condition and what causes it, but what is different in this case is the fact that the trailer is in storage when I've been shocked. No shore power, no generator, and even the battery has been disconnected (using the built-in disconnect switch).
My suspicion is that voltage is being induced by some overhead high-voltage power lines that are directly over the storage facility. On a humid day, you can "hear" the power lines "crackling." I've searched around and haven't found any similar situations described.
Have you ever heard of anything like this? I'm planning to attach a ground wire to a ground post and attach it to the RV frame while it's parked to try and dissipate any voltage. Thanks in advance. —Dave
Dear Dave,
Anytime a large metallic object like an RV is underneath high-voltage power lines there’s a significant voltage induced on its chassis and body which can range from a few hundred to several thousand volts. That’s due to magnetic/capacitive coupling, and it’s a very well-defined problem out West where there’s 500,000-volt power lines running over top of roadways and parking lots.
Now, there’s very little fault current at your RV available from this coupling, perhaps 1mA, so it’s not dangerous at all. But the induced potential can be upwards of 10,000 volts. And even this small amount of fault current is sufficient to startle you from a shock, which could cause you to fall off a ladder or roof.
This is such a big issue on farms out west that one of the large power company briefs suggests that you add a ground rod to metallic objects under power lines such as metal sheds, fences and irrigation pipes. So I think that adding a ground rod in your case is a good idea. Make sure there’s not underground wiring or pipes where you plan to drive a ground rod (call your local utility first) and use a standard 8-foot rod you can purchase from Lowe's or Home Depot.
Here’s a very informative article about living safely around high-voltage power lines from the Bonneville Power Association. You can download and read it below.
Note that I talked to the author of this article a few years ago, and they confirmed my suspicions that there could be sufficient induced voltage in an RV parked under high-tension lines to allow a grounded spark plug clamped to your bumper to spark continuously. They said the current would be under 5mA and not deadly, but if any of you have ever touched a lawn mower spark plug while the engine was running you’ll know just how much it hurts. Ask me now I know this!!!
Let’s play safe out there…. Mike
