Shocking !

[Lanark Camper]

My next door neighbour just bought an 18’ 2016 Palomino trailer. They set it up and plugged it in to a 15 A plug in their garage. When she went to open the door she got a shock that almost knocked her down. I went over with a VOM and measured 65 V AC from the trailer frame to earth - literally pushed one probe into their dry lawn the other on the frame.
They were using the 30 A power cord, a new adaptor to a 15 A power cord. I checked the plug in the garage for reversed polarity, bad ground and it looks ok. We then noticed the 15 A power cord had no ground pin. We used a proper 15A cord and no more power on the trailer frame.

I think there is still a problem but not sure what to tell them. The dealer that sold it to them is quite a distance away, so probably better to diagnose a problem before hauling it back there. I think they feel the problem is solved. I’m concerned plugging into the wrong campground outlet could be a disaster.

I’m not keen to start taking their trailer apart to diagnose the problem. I just thought that maybe this has come up before. So if a couple of measurements could prove to the dealer what needs to be fixed I’d be happy to do that.

Suggestions ?

Bob

[rubicon327]

Bob,
Read my posts on this thread starting at #12! Do they have a dual mode hot water heater? May be a burnt out electric element that failed hot-to-ground. I suppose a 120V refrigerator heating element could do it too. With a good ground prong the electrified shell will be no longer since you gave the current a proper ground path but if they plug the trailer into a GFI outlet I guarantee it will trip instantly.
https://www.escapeforum.org/forums/f...tml#post145401

[Greg A]

Sometimes Manufacturers or previous owners have just wired something wrong and caused the trailer to be energized as your describing. It can also be caused by things like a staple that went through a wire during assembly. It unfortunately happens more frequently than one wishes.
Here is a fairly good post on finding out if it's in the pedestal, cord or trailer wiring.
https://www.everything-about-rving.c...ocking-me.html

There are quite a few of these and youtube videos out there on the problem. Do Google searches for things like "trailer door electric shock" "RV shocking me" etc.

[Lanark Camper]

Originally Posted by rubicon327

Bob,
Read my posts on this thread starting at #12! Do they have a dual mode hot water heater? May be a burnt out electric element that failed hot-to-ground. I suppose a 120V refrigerator heating element could do it too. With a good ground prong the electrified shell will be no longer since you gave the current a proper ground path but if they plug the trailer into a GFI outlet I guarantee it will trip instantly.
https://www.escapeforum.org/forums/f...tml#post145401

Thanks ! Great thread, I read the whole thing. I’ll go over and checkout their hot water tank for dual mode. If so I’ll unplug the trailer and do a few resistance measurements between the element, tank, and trailer ground.

So when the hot water tank element is damaged it shorts to the grounded tank but there is enough resistance in this circuit that the current flowing through the ground conductor doesn’t trip a breaker ? If the element is 1400 W that’s a 15 A breaker and a deadly situation.

Regards, Bob

[Lanark Camper]

Originally Posted by Greg A

Sometimes Manufacturers or previous owners have just wired something wrong and caused the trailer to be energized as your describing. It can also be caused by things like a staple that went through a wire during assembly. It unfortunately happens more frequently than one wishes.
Here is a fairly good post on finding out if it's in the pedestal, cord or trailer wiring.
https://www.everything-about-rving.c...ocking-me.html

There are quite a few of these and youtube videos out there on the problem. Do Google searches for things like "trailer door electric shock" "RV shocking me" etc.

Thanks Greg, great link ! I book marked it. I’ll pass it on to my neighbours.
Bob

[Lanark Camper]

For anyone interested in RV shore power dangers here is an interesting thread,

https://heartlandowners.org/archive/...p/t-32982.html


Bob

[tdf-texas]

Originally Posted by Lanark Camper

My next door neighbour just bought an 18’ 2016 Palomino trailer. They set it up and plugged it in to a 15 A plug in their garage. When she went to open the door she got a shock that almost knocked her down. I went over with a VOM and measured 65 V AC from the trailer frame to earth - literally pushed one probe into their dry lawn the other on the frame.
They were using the 30 A power cord, a new adaptor to a 15 A power cord. I checked the plug in the garage for reversed polarity, bad ground and it looks ok. We then noticed the 15 A power cord had no ground pin. We used a proper 15A cord and no more power on the trailer frame.

I think there is still a problem but not sure what to tell them. The dealer that sold it to them is quite a distance away, so probably better to diagnose a problem before hauling it back there. I think they feel the problem is solved. I’m concerned plugging into the wrong campground outlet could be a disaster.

I’m not keen to start taking their trailer apart to diagnose the problem. I just thought that maybe this has come up before. So if a couple of measurements could prove to the dealer what needs to be fixed I’d be happy to do that.

Suggestions ?

Bob

Here's how to find the problem.

Turn off all the breakers in the trailer and plug the trailer back into the outlet using the 15 A power cord with no ground pin. Measure voltage to ground. If bad, problem is in the wiring to the breaker box.

Turn on one breaker at a time and check the voltage to ground. When the voltage to ground reads bad, that breaker is the circuit that has the problem. Continue one breaker at a time until the bad circuit shows up then troubleshoot that circuit to find where the hot is shorting to ground.

There may be more than one circuit giving the owner problems. Once you have repaired the circuit that shows a short from hot to ground, continue with the rest of the breakers one at a time to see if any other circuits have a short.

[steve dunham]

Since your neighbor bought a used trailer , the previous trailer owner may have modified the wiring . The neutral conductor and the equipment grounding conductor in a trailer are isolated from each other . If someone used the equipment grounding conductor as a neutral , which is an unsafe condition , it will becomes evident when you break the ground prong off the trailer cord or plug the trailer into an ungrounded receptacle
Tom gave a good explanation on how to troubleshoot the problem

[rubicon327]

Originally Posted by Lanark Camper

So when the hot water tank element is damaged it shorts to the grounded tank but there is enough resistance in this circuit that the current flowing through the ground conductor doesn’t trip a breaker ? If the element is 1400 W that’s a 15 A breaker and a deadly situation.

Bob: I think it depends on exactly how the element fails as it burns up. I'm not an electrical guru. Know just enough to stay out of trouble. tdf-texas and steve can guide you better. I just know that when I isolated trailer power and removed the electrical connections from the HWH element and then plugged the trailer back in it no longer tripped the GFI. You cannot simply turn off the breaker to test as the ground fault will still be present. Once the element was replaced I no longer had any issues. A bad element will read 0 ohms when you measure with a multimeter. A good element is supposedly around 10-12 ohms. A bad element will be obvious when you look at it. Hope this helps.

[Lanark Camper]

Thanks for all the good advice. I’m hesitant to get too far into this problem. They did get a guarantee with the purchase . It only came home on Friday night.
It has been unplugged. They are waiting to deal with the dealer later in the week. Wednesday is Canada Day up here so not much happening today or the next few days. Their service dept has been closed since last Saturday.
I went over this morning. Took the cover off the water tank heating element it measures a few ohms between the terminals. No continuity to ground, tank or trailer frame. The tank was full of water.
I suggested they contact the dealer and see what they say.
Once it’s been fixed we will open the ground and check it again.
Your troubleshooting advice may be used if they can’t get satisfaction from the dealer.
Bob

[tdf-texas]

Originally Posted by Lanark Camper

Thanks for all the good advice. I’m hesitant to get too far into this problem. They did get a guarantee with the purchase . It only came home on Friday night.
It has been unplugged. They are waiting to deal with the dealer later in the week. Wednesday is Canada Day up here so not much happening today or the next few days. Their service dept has been closed since last Saturday.
I went over this morning. Took the cover off the water tank heating element it measures a few ohms between the terminals. No continuity to ground, tank or trailer frame. The tank was full of water.
I suggested they contact the dealer and see what they say.
Once it’s been fixed we will open the ground and check it again.
Your troubleshooting advice may be used if they can’t get satisfaction from the dealer.
Bob

Or the service department has a wait time like the ones around here. The camping season would be over by the time they looked at the trailer.