Good source for RV, AC electric information

[tbutler]

This web site has great information on AC electric.

http://www.myrv.us/electric/

I found the section on open neutral to be particularly enlightening (or frightening).

[wolfe10]

This web site has great information on AC electric.

http://www.myrv.us/electric/I found the section on open neutral to be particularly enlightening (or frightening).

Tom,

Indeed the most damage we have ever seen to coachs' 120 VAC systems was from an open neutral in a high-end CG in Vermont. AN EXCELLENT REASON FOR CHECKING VOLTAGE AND POLARITY BEFORE PLUGGING IN.

As always, I checked the CG outlet before plugging in with my Fluke meter and read voltage varying from 145-177 VAC!. Sent Dianne up to the office for repair or other site. Checked voltage at second assigned site and read the same. Finally, (Dianne and CG owner not happy campers at this point) another site on the other side of the park where voltage was fine (118 VAC). Ya, you guessed it, "no one else has complained-- must be my problem".

After setting up camp, went over to the "high voltage" area and asked several campers if they were experiencing high voltage. You guessed it, no one else had checked voltage, but ALL were running on 160+ VAC when I checked their sites. Several thousand dollars worth of A/C's, TV's and microwaves damaged.

After two days of digging with a backhoe, the electric contractor found a break in the neutral wire under a culvert.

Moral of the story-- always check voltage and polarity before plugging in (and check voltage again as you add high-amp loads).

Brett Wolfe

[stevesandidge@yahoo.com]

AMEN Brett. can we like tatoo that on folks hands? put a decal on thier shore power cords? and a good website as usually tom.

steve

[tbutler]

The thing that worried me about his discussion of an open neutral was that this was damaged, not completely open. It only showed itself under a large continued load. He says it would pass the normal testing most people who test would do. He also says that the normal surge protector and its tests for proper wiring wouldn't detect this problem. So even if you do routine testing, it would look good and then when you turned on the water heater, microwave and coffee pot, things would go awry. He doesn't go on to describe how he would recommend testing. I can envision using several portable heaters or other devices to induce a large load but even that wouldn't be like turning on two air conditioners, the water heater and the coffee pot. So how do you stress the circuit so it would show a damaged (potentially open) neutral line?

I thought the explanations of the neutral and ground lines was excellent and the diagrams and explanation for wiring 30 amp and 50 amp outlets for RV's as opposed to other kinds of wiring that electricians normally do should help RV'ers explain to an electrician what they want done when installing a home outlet, even if they aren't doing the work themselves. Good explanation of how to do testing and what the readings from the tests should be also. I hope everyone takes the opportunity to visit this site.

[wolfe10]

Tom,

An OPEN neutral is easy to diagnose-- voltage will be way off from 120 VAC plus/minus 10 VAC.

What he found was not an open neutral, but a neutral connection with a lot of resistance (enough resistance to cause enough heat to melt insulation and discolor wires). There was enough conductivity to handle small amp loads, but not high-amp loads.

I can no think of a way to detect this either except to have a digital voltmeter/polarity checker plugged in all the time (and monitored when larger loads applied).

Both AEC and Good Governor made/make these. I have used one for the last decade on our coach. Have not yet run into a "partial neutral", but, a fair number of mis-wired outlets. This is particularly true in Mexico, where until recently no ground was required, so reverse polarity a frequent issue (frequent enough that I a made a reversible adapter to quickly and inexpensively "reverse it").

With one of these monitors (they plug into any standard house-type outlet in your coach) one can be careful without having to go overboard to paranoid. It becomes second nature to check the meter when adding heavy loads.

Brett Wolfe

[stevesandidge@yahoo.com]

yeah i have the good govenor too and even use it as a tech when i do mobile service, as ya never know what you are gonna find in the campgrounds. i always test park pedestals with it before i hook up my mh. i even made a test rig that lets me check the 50 amp plug, by isolating the hots to each recep and then use the govenor to check out the connections.

steve

[tbutler]

I had to look up good governor to see what it is. I have the same thing built in on my coach. It has an Aladdin system which monitors voltage/amperage/cycles on both 50 amp circuits. I have a plug in tester for polarity reversal so have all the basics and have been using them pretty much on a routine basis. And yes, I always check as the air conditioners, microwave, water heater, etc. come on after we get into a campsite to see what the voltage is doing. Can't be too careful.