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.

[dedmiston]

We've crossed into the realm of personal jabs and wiener measuring. I knew it was just a matter of time.

[time2roll]

Gdetrailer wrote:
But obviously you have never dealt with old homes or apartments in Cities..

You may have underestimated me.

[Gdetrailer]

time2roll wrote:
As you please. I would rip it all out.
After 100 years if you can't renovate this stuff it might be time to sell the house and get something updated.
I stand with your brother on this.

Sorry you "stand with my Brother", he isn't in reality and standing with him, you have no clue. There is "book smart" and there is "street smart", I would rather stand on the "Street Smart" side of life..

Fortunately my house didn't have knob and tube when I bought it, but it did have some interesting wooden wire "race way trays" in the attic crawl space which tells me it may have had some at one time in it's life.

But obviously you have never dealt with old homes or apartments in Cities.. You don't just "tear out" stuff, it becomes a very long drawn out process of permits, inspections and in the case of "landmarks" or "historical" buildings the added restrictions of making everything go back and look like it is done accurately for the time period..

Fortunately for myself, home is outside a city which made life much easier.. As far as my homes electrical system goes, it IS fully updated, including 200A service entrance (replaced old 60A fuse box) with new breaker panel, new grounding system, all new wiring, new outlets.. Fully inspected and passed by my PoCos approved inspector (on edit, I should note: Fully up to date to code at the time of the inspectors approval). My home had no insulation and lots of warped 3/8" drywall, made decision easy to gut and replace.

I have also done rework on multiple homes with old systems along with wiring some new homes from scratch so I am no stranger to electrical work.

[BCSnob]

I too would replace the “knob & tube” and I have replaced the first generation non metallic sheathed cable (hot & neutral) electrical wiring in my 200 year old house. It was too risky as a fire hazard. The electrician who did the work remarked that most of the wiring was still in very good condition.

However, the horse hair plaster is more durable than new wallboard, the wood framing was old growth red oak which is more durable than the open grain fir used now, and the mortise and tenon joints are longer lasting than nails or screws. Newer is not always better.

[time2roll]

As you please. I would rip it all out.
After 100 years if you can't renovate this stuff it might be time to sell the house and get something updated.
I stand with your brother on this.

[Gdetrailer]

time2roll wrote:
Some grandfathered items are still worth updating.
The electricity does not care about an exemption... it will still bite just as hard.

Some are, some are not, but in reality one could spend a lot of money on electricians, materials, carpenters, drywall folks following every rabbit hole of changes that do not add safety.

Have had this conversation multiple times with a Brother that is an Architect.. In his world everything must be demoed and replaced with new in order get up to every new standard. He can't understand why Clients tend to balk at his ideas.. All well and good if you are made of money.

Heck even "Knob and Tube" wiring is still in use and grandfathered in old, old buildings. Talk about a very dangerous and scary wiring system where switches and fuses are often on the neutral side and you have runs of potentially bare wires floating about and turning a switch off or removing a fuse leaves you with a still Hot connection.. But it still works and can be still somewhat safe as long as you don't mess with it, add on to it or cover the wires with building insulation.

[time2roll]

Some grandfathered items are still worth updating.
The electricity does not care about an exemption... it will still bite just as hard.

[CA_Traveler]

I actually had 160/80V with a 30/50 adapter one night while plugged into a 30A pedestal and I couldn't unplug fast enough. However my EMS shut down the RV power in milliseconds before the smoke escaped.

The problem was a open neutral in the 120/240V CG distribution panel. Very rare of course. Not as rare however is a 50A open neutral due to pedestal or RV wiring and one reason I've posted using a EMS especially for 50A. Mine is a PI HW 50C with an inside remote display.

[CA_Traveler]

Mike134 wrote:

CA Traveler wrote:
In the years I've been on various forums electricity is hands down the least understood topic. In 2004+ the top item was 50A RV power. It just shows how little is understood about house power which is the same except that a house us usually 100A, 200A, etc.

ie Its 120/240V 50A 3 pole 4 wire 60 Hz SINGLE PHASE and 12,000 watts.

And a 50A open ground is yet another mystery. Not being critical as there is much about a lot of things that I don't know.

I think you meant to say open neutral. That will cause some devices to see a high voltage say 180V while another sees 60volts.

Thanks for catching that typo!

[Gdetrailer]

CA Traveler wrote:
In the years I've been on various forums electricity is hands down the least understood topic. In 2004+ the top item was 50A RV power. It just shows how little is understood about house power which is the same except that a house us usually 100A, 200A, etc.

ie Its 120/240V 50A 3 pole 4 wire 60 Hz SINGLE PHASE and 12,000 watts.

And a 50A open ground is yet another mystery. Not being critical as there is much about a lot of things that I don't know.

Actually, 120/240 US home entrances are referred to as SPLIT PHASE, sometimes as a TWO PHASE STEP DOWN.

See HERE

"240V or split phase: For small residential buildings, the usual method is to rig up a 240V stepdown transformer (instead of 120V) in which the secondary winding is split into two 120V windings (hence the name "split phase"). The center tap is then grounded and fed to the house as if it was the neutral wire of the old 120V system, and each end is wired as a separate 120V live wire. Their waveforms have a half-cycle offset, or 180 degrees, when measured against the neutral wire. The normal 120V designed machinery does not care which live wire you use for them as long as you connect them between a live and neutral wire. Appliances in the home can be distributed on either live wire to maintain balanced loading, and when heating requires high power, the concerned appliance can be connected to both live wires to operate the heating element, providing 240V for it. "

The key here is while the PoCos transformer for residential service is only connected to one of three "phases" and the step down transformer that feeds your home service entrance actually looks like two 120V windings which for 240V are wired in series.

Because each 120V winding must be wired in series to provide 240V the center tap point is used as the Neutral creating two 120V outputs that have a 180 degree reversal in waveform when referenced via the Neutral..

Note the two bottom drawings at the link I provided..

The bad thing of 120V/240V setup like 50A RV is if you lose the neutral, 120/240 works by balancing the loads and with no Neutral your 120V loads now become part of simulating the center tap which changes the voltage potential each 120V appliance sees..

HERE is a good video explaining electrical systems "101" which may be helpful.

HERE is a video concerning main panel and Neutral/ground bond.

HERE is a video concerning sub panel separate neutral/ground wires.

On edit..

In the last video which is about sub panels it was mentioned that the NEC code was updated in 2008 to require separate isolated ground and Neutral in sub panels..

So, it IS very possible that RVs as new as 2007/2008 may have ground and Neutral connected in the panels..

But once again, OLD work is Grandfathered, you do not have to change or modify existing OLD work to match newer codes unless you change panels or make major modifications to the electrical system..

However, the last video on sub panels should very clearly give you a good reason to make the upgrade change.. I give that guy some Kudos for the video.

[Mike134]

CA Traveler wrote:
In the years I've been on various forums electricity is hands down the least understood topic. In 2004+ the top item was 50A RV power. It just shows how little is understood about house power which is the same except that a house us usually 100A, 200A, etc.

ie Its 120/240V 50A 3 pole 4 wire 60 Hz SINGLE PHASE and 12,000 watts.

And a 50A open ground is yet another mystery. Not being critical as there is much about a lot of things that I don't know.

I think you meant to say open neutral. That will cause some devices to see a high voltage say 180V while another sees 60volts.

[CA_Traveler]

In the years I've been on various forums electricity is hands down the least understood topic. In 2004+ the top item was 50A RV power. It just shows how little is understood about house power which is the same except that a house us usually 100A, 200A, etc.

ie Its 120/240V 50A 3 pole 4 wire 60 Hz SINGLE PHASE and 12,000 watts.

And a 50A open ground is yet another mystery. Not being critical as there is much about a lot of things that I don't know.

Update: And a 50A open neutral is yet another mystery.

[sayoung]

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.

I was haveing a GFCI problem . After 8 years the plug started tripping. I replaced it and all was well for about a week then it to started tripping. I started looking for a possible cause and started in the breaker box. I'm laying on the floor staring at the wiring when I see a romex with the neutral on the gnd bus & the gnd on the neutral bus. How that GF plug ever worked is beyond me. Something to check for.

[Gdetrailer]

Mike134 wrote:

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.

Correct!

That trailer would trip my house outside outlets GFCI shortly after a heavy rain storm until I separated the neutral and ground in the RV panel.. Trailer tongue sitting on a soaking wet board surrounded by wet ground = nuisance GFCI trips..