How to use volt meter

joebedford wrote:
I know how to use a DVM. Maybe I've been lucky but I've never tested an outlet before plugging in. How many people actually have problems? (yes, I know it happens sometimes).

Perhaps I'm just a magnet for these things, but I have emails from hundreds of RV users across the country who have experience pedestal and home outlet problems of all kinds. Most of the home/garage outlet issues are due to open grounds, which will allow any leakage currents inside your RV to move from a few volts above earth potential, up to 120-volts potential. I also have perhaps a dozen direct emails from readers who had an "electrician" mis-wire a TT-30 Amp outlet with 240-volts instead of 120-volts on their house (for driveway powering of their RV). Those were all disasters, with one electrician suggesting the RV owner run the insurance claim of $20,000 thru their homeowner insurance policy since he didn't want to pay for the damages. I can see Google searches that find NoShockZone and get perhaps 100 searches per week asking what happens when you plug a 120-volt RV into a TT-30 outlet mis-wired with 240-volts. Yes, there were 5,000 Google searches that found NoShockZone.org using that key word string in the last year alone.

I also was at one campground in Texas last year where an electrician accidentally wired up a bunch of 20 and 30 amp outlets at new campsites with 208-volts instead of 120-volts. The campers were complaining their RV electrical systems were burning up, and the campground owner said it must be due to "lightning strikes". But one smart camper metered his pedestal outlet before plugging in and figured it out. The electrician had hooked into something called a high-leg Delta bus, fairly common with 1970's industrial wiring, especially in the mid-west. And yes, these were BRAND NEW pedestal boxes at new campsite pads.

And I'm cataloging a number of RPBG (Reverse Polarity Bootleg Ground) outlets around boat docks and home garages which we suspect was the cause of electrocution deaths of at least several swimmers and RV owners in the last year. See http://www.rvdoctor.com/2001/07/friends-of-gary-mike.html for an explanation of why an RPBG is so dangerous and impossible to detect using standard measuring tests.

I've also had several complaints from a state campground were every singe pedestal outlet was wired with reversed phase (swapped H-N). While not immediately dangerous, reversed H-N phase is a code violation and easily discovered with even a $5 3-light outlet tester.

A few of my EE buddies who are RV owners have also complained that campgrounds often use "workcampers" to wire pedestal outlets, and they suspect that could be one of the causes of mis-wiring.

Now, I don't want to be a doomsayer, but note that most of the advice that's given to RV owners who find a bad outlet is to simply ask for a new campsite. Few if any of them are told to notify the campground owner about the problem, just leaving it for the next unlucky RV to plug into. I think that's socially irresponsible, since a mis-wired outlet can easily cause an RV to have hot-skin condition, and that could electrocute (read KILL) the next person who plugs into it.

Mike Sokol
www.NoShockZone.org