RV Hot Skin (Exterior electrification)

[sgtsteve]

This past weekend my wife was electrocuted when she stepped onto the trailer steps and grabbed the handrail while in bare feet. She was subsequently thrown from the rig and landed in the grass. She sustained a broken L. Foot and an injured R. Hand in the fall. The trailer was plugged into an outlet on my garage. So how did this happen? It seems we have been doing something wrong for many years. I plug the RV power cord into an exterior household extension cord which I then plug into an exterior outlet on my garage. In doing some research, I found the topic of "RV Hot Skin" which relates to the electrification of the exterior of the trailer. Apparently, using a household extension cord in combination with the RV power cord is a no no. I have been told that action can actually cause a reverse polarity which becomes a hazard. Using a voltage checker revealed that parts of my trailer's exterior was registering 9 to 16 volts. However, no circuit breakers in the trailer were thrown and there is no "Hot skin" when the trailer is not plugged in. To further test this theory, I am going to go to a local campground and plug into an appropriate power tree and again test the exterior of the trailer.

I'll bet there a lot of folks like me that have been making this same mistake and never knew there was a problem. If my wife had not been in bare feet she probably would have been fine. What makes this more embarrassing is that we have been travel trailer owners for 20 years. We are so very thankful my wife is gonna be ok, but this was definitely a tough lesson to learn.

[Mike134]

Gdetrailer wrote:

enblethen wrote:
I would not jump out and do anything until the shore power cord is identified whether it is two or three wire! If it is two wire you are asking for problems!

However, I did have a 1981 TT . That panel most definitely had all neutrals and grounds connected via a single ground/neutral buss bar..

So, in reality it is possible to find RVs with 30A shore cord but yet neutral and ground connected together.

That would explain folks saying they got shocked off the "skin" of the trailer when plugged into a receptacle that was wired with reverse polarity.
With today's wiring standard of separately insulted neutral and ground, "reverse polarity" would not cause the skin to become electrified.

[enblethen]

I haven't seen anything. OP talked about getting "tester".
I didn't see much information back on how the rig is connected to outlet. Adapter? type of extension cord.
Talked about installing GFCI receptacle.

[Mike134]

Has anyone seen a replay from the original post if he troubleshot his problem over the weekend?

[enblethen]

It may not be as easy to replace the shore power cord. Would need to identify 120 volt power center if it even has one. Many of the older two wire system didn't have them. They relied on the protection in the supply location.

[Mike134]

enblethen wrote:
I would not jump out and do anything until the shore power cord is identified whether it is two or three wire! If it is two wire you are asking for problems!

This!!! Make sure you fully understand grounded conductors vs. grounding conductors before modifying your existing system.

[Gdetrailer]

enblethen wrote:
I would not jump out and do anything until the shore power cord is identified whether it is two or three wire! If it is two wire you are asking for problems!

Granted, if the shore cord is two wire then all bets are off..

However, I did have a 1981 TT which was factory wired with a small 4 half breaker breaker panel fed via 3 wire 30A shore cord. That panel most definitely had all neutrals and grounds connected via a single ground/neutral buss bar..

That TT electrical system was all original but the panel only offered 3 circuits (Main 30A breaker and 3 15A breakers) and the converter was a separate linear deck mount. 3 circuits didn't cut it for modern day use..

I did change out that small panel for a larger panel and at that time I updated to having the neutral and ground separate.

So, in reality it is possible to find RVs with 30A shore cord but yet neutral and ground connected together.

[time2roll]

If the utility cord is a two-wire, this would be a great time to replace that too.

[enblethen]

I would not jump out and do anything until the shore power cord is identified whether it is two or three wire! If it is two wire you are asking for problems!

[Gdetrailer]

time2roll wrote:

mr_andyj wrote:
It is plugged in now so dont want to take it apart just yet, but best I remember is it did look factory, not just wires going in odd places, the neutral looked like it was factory made to be grounded where it was, but I cant say for sure that it was not just grounded to the ground bar.

Nonetheless, would it be wise to unground it? That would mean the neutral is only connected to the neutral of the extension cord, not the ground of the panel that connects to the ground of the extension cord.

I can do electrical just fine, but am not an electrician that knows the codes.

Yes the neutral bus and ground bus in an RV should be separated. RV panel is a sub-panel.

Neutral-ground bond should only be made at the main power source panel supplied by the utility transformer.

Existing old electrical systems are "Grandfathered", as long as you do not mess with it, it is Grandfathered and does not require you to update the wiring to modern codes.

Is it ideal? no.

Would it be good to correct, sure, if possible.

Although before going through that hassle, verify that the buss used is not "split", sometimes those buss bars in RV panels are jammed in there so close but may be two separate Busses.

If that is the case, all grounds will be on one side of the buss and neutrals on the opposite side. If grounds and neutrals are mixed in any order on that buss then yeah, the grounds and neutrals are connected together.

To correct, you may need a isolated Buss bar which comes with isolated pedastool, looks like this..



Found HERE

Put all the neutrals on the isolated buss bar and all the grounds on the existing buss bar (provided that bar is bonded to the metal panel).

Can you take a picture of the buss you have?

[time2roll]

mr_andyj wrote:
It is plugged in now so dont want to take it apart just yet, but best I remember is it did look factory, not just wires going in odd places, the neutral looked like it was factory made to be grounded where it was, but I cant say for sure that it was not just grounded to the ground bar.

Nonetheless, would it be wise to unground it? That would mean the neutral is only connected to the neutral of the extension cord, not the ground of the panel that connects to the ground of the extension cord.

I can do electrical just fine, but am not an electrician that knows the codes.

Yes the neutral bus and ground bus in an RV should be separated. RV panel is a sub-panel.

Neutral-ground bond should only be made at the main power source panel supplied by the utility transformer.

[enblethen]

Mr_Andyj:
What type of shore power cord do you have? 3 wire 30 amp TT30R?

[mr_andyj]

It is plugged in now so dont want to take it apart just yet, but best I remember is it did look factory, not just wires going in odd places, the neutral looked like it was factory made to be grounded where it was, but I cant say for sure that it was not just grounded to the ground bar.

Nonetheless, would it be wise to unground it? That would mean the neutral is only connected to the neutral of the extension cord, not the ground of the panel that connects to the ground of the extension cord.

I can do electrical just fine, but am not an electrician that knows the codes.

[Gdetrailer]

mr_andyj wrote:
I have a panel out of a 1971 camper.
The neutral is grounded at the panel. The neutral is grounded, as many are saying yet others somehow want to disagree with such facts...

What some here are saying is that this code has changed and now the neutral is not supposed to be grounded at the panel?

Should the neutral be un-grounded and let the neutral ground effect take place at the house panel, not the caper panel? Would this help eliminate some possible issues with reverse hot skin?

If the wiring looks untouched and original (never messed with) like it came from the factory then at that time that would have been acceptable practice and would be "Grandfathered" today.

I believe code was updated in the 1980s-90s to define how subpanels were to be treated concerning ground and neutral connection and possible additional ground rods on remote subpanels (like a remote unattached garage with a subpanel).

Even though your system should be Grandfathered, if you have the space in your panel to add a buss bar you could update the panel with a ground isolated neutral and a separate ground bar.

Note, some panels that are all metal will have a grounding screw or a grounding lug that connects the buss bar to the metal panel or sometimes the buss may be mounted directly to the metal of the panel.. For panels that the buss is mounted directly to steel you will need a buss bar with insulators..

While technically having neutral and ground connected together in a subpanel will cause no harm, the idea of isolating the two is all about not having a live voltage potential from current on the neutral showing up on your safety grounded equipment..

[enblethen]

I go back into the early 70s with the electrical code. The only rigs that had the neutral and ground bonded in an RV was those with a two wire 15/20 amp connection.
Some "electricians" bonded them not knowing what they are doing.
When I taught electrical classes many electricians left after Chapter 4 saying "I never work on " specials in Chapters 5 through *".

[Mike134]

mr_andyj wrote:
I have a panel out of a 1971 camper.
The neutral is grounded at the panel. The neutral is grounded, as many are saying yet others somehow want to disagree with such facts...

What some here are saying is that this code has changed and now the neutral is not supposed to be grounded at the panel?

Should the neutral be un-grounded and let the neutral ground effect take place at the house panel, not the caper panel? Would this help eliminate some possible issues with reverse hot skin?

My history with the code only goes back to 1981 and back then the neutral was only bonded (connected) one time at the incoming service to the ground wire/ground rod/waterpipe.

Not sure if it was ever permitted further "downstream" in older versions of the code. That said I have run across electricians with 45+ years of experience and they still screw up today and connect the neutral to the metal circuit breaker enclosure even though it's a sub panel (like your RV panel)