Electric shock through screen door

[azeeb]

A few weeks ago I remember seeing a thread from somebody about feeling a slight electric shock through the screen door. I lost track of the post and didn't see if there was a resolution.

Today I had the same issue with my new 2017 25FB. I tested things a bit and it seemed to go away when the radio was turned off. I am plugged into a 15 amp circuit at my wife's grandpas house. The circuit tests correct with my plug in tester.

Has anyone else had this problem and figured out how to fix it? Now I can't reproduce it, so it seems intermittent. When I get a chance I'm going to pull the stereo and look for a loose connection.

[190-b-651]

Definitely a grounding problem

[GCinSC2]

Please watch this video.

https://www.youtube.com/watch?v=Y8h64X33aKg

[AtomicNo13]

Not a grounding problem.
Get it checked by a qualified electrician.... Don't die

[TG Twinkie]

Sounds like the hot and neutral are connected wrong.
The neutral and ground should not be bonded.

[kendrick.l.j]

Please do not try to use your Airstream until you get a licensed, qualified, professional to check it out. In the meantime cut the power to the box first then disconnect from source.

[AtomicNo13]

That video is flawed....
Just because the ground is lifted doesn't mean the skin will be hot.
Only a reverse hot neutral will cause a hit skin.
A short will not cause a hot skin either.

[OTRA15]

Originally Posted by azeeb

A few weeks ago I remember seeing a thread from somebody about feeling a slight electric shock through the screen door. I lost track of the post and didn't see if there was a resolution.

Today I had the same issue with my new 2017 25FB. I tested things a bit and it seemed to go away when the radio was turned off. I am plugged into a 15 amp circuit at my wife's grandpas house. The circuit tests correct with my plug in tester.

Has anyone else had this problem and figured out how to fix it? Now I can't reproduce it, so it seems intermittent. When I get a chance I'm going to pull the stereo and look for a loose connection.

Ditto to earlier posts, this is a dangerous situation. First cut the power to the outlet where your shore power is plugged in [circuit breaker?], then unplug your shore power ASAP and have a competent electrician check out the situation.

Here is the thread you were thinking of IMO:

http://www.airforums.com/forums/f317...cy-170032.html

The OP in that thread, John Oliver, has not posted since the date of the OP in that thread. Hope he is OK.

Good luck!

Peter

[GCinSC2]

Originally Posted by AtomicNo13

That video is flawed....
Just because the ground is lifted doesn't mean the skin will be hot.
Only a reverse hot neutral will cause a hit skin.
A short will not cause a hot skin either.

Suggest you contact Mike Sokol and discuss or review with him. Mike has some pretty extensive electrical safety information and presentations on RV electrical systems http://noshockzone.org/15/

[Al and Missy]

Originally Posted by AtomicNo13

That video is flawed....
Just because the ground is lifted doesn't mean the skin will be hot.
Only a reverse hot neutral will cause a hit skin.
A short will not cause a hot skin either.

As a single failure, you are correct. But a defective component in any AC-powered appliance could make the skin hot if the ground connection is broken. It is common practice to bypass or filter both the AC hot and neutral to ground to minimize conducted or radiated noise. A bad component in that circuit could provide a path from hot to ground. In the absence of a ground connection, the skin would be hot. Another case is a hot wire with the insulation rubbed through.



Al

[uncle_bob]

Hi

If you have a very normal filter on a radio or computer, you will see about 60V on an ungrounded chassis. The problem will come and go as the device is turned on and off (as long as the filter is after the power switch).

Are you plugged into grandpa's house with a two wire plug (or three wire to two wire adapter)? If so, yup you will have voltage on the ground.

When you plug your circuit tester into the plug at grandpa's do the lights come on correctly?
(Do you have a plug in tester? If not go get one now !!!)

Odd things happening with ground are fairly common. They can be very dangerous. Having a tester alway plugged into a socket in the trailer is a really good idea. Having a surge arrestor that also detects ground issues is (to me) well worth the money that one costs.

Not a good situation.

Bob

[Al and Missy]

Good Point uncle_bob. I didn't think about the voltage divider effect of two caps to the ungrounded trailer ground. The good news is, at typical values, the source impedance is quite high and will tickle you but probably not hurt you.

I carry an outlet tester with the intent of checking power at each stop but I rarely remember to do it. I like your idea of leaving it plugged in. Now if I can just remember to look at it. That's the problem I have with my line voltage meter, which is always plugged in.

Al

[uncle_bob]

Originally Posted by Al and Missy

Good Point uncle_bob. I didn't think about the voltage divider effect of two caps to the ungrounded trailer ground. The good news is, at typical values, the source impedance is quite high and will tickle you but probably not hurt you.

I carry an outlet tester with the intent of checking power at each stop but I rarely remember to do it. I like your idea of leaving it plugged in. Now if I can just remember to look at it. That's the problem I have with my line voltage meter, which is always plugged in.

Al

Hi

I deserve no credit at all for the tester idea. The dealer plugged one in when the trailer was delivered. It's in the outlet by the stove so it's easy see. Our surge protector has a "time out" on it. For whatever reason it's quicker to look at the voltage tester to see if we have 120V than it is to see if the clock on the microwave is lit up.

The 60V on the ungrounded chassis I found out long ago .... learning by doing ....

Bob

[azeeb]

Originally Posted by uncle_bob

Hi

If you have a very normal filter on a radio or computer, you will see about 60V on an ungrounded chassis. The problem will come and go as the device is turned on and off (as long as the filter is after the power switch).

Are you plugged into grandpa's house with a two wire plug (or three wire to two wire adapter)? If so, yup you will have voltage on the ground.

When you plug your circuit tester into the plug at grandpa's do the lights come on correctly?
(Do you have a plug in tester? If not go get one now !!!)

Odd things happening with ground are fairly common. They can be very dangerous. Having a tester alway plugged into a socket in the trailer is a really good idea. Having a surge arrestor that also detects ground issues is (to me) well worth the money that one costs.

Not a good situation.

Bob

We were plugged in with a three wire adapter. I checked the outlet with my circuit tester before plugging in, and it was good. It could very well be an intermittent problem with that outlet. It is an old house. I have a surge protector with a built in tester too. Thanks for the tip on leaving the tester plugged in inside the trailer. It seemed odd to me that the screen door seemed to be the only thing that was hot. Touching anything else I couldn't feel anything. It didn't feel like 110v either. It was just enough for me to barely feel.

We have since left his house for a campground. I will keep an eye on things.

[uncle_bob]

Hi

The side of the trailer has plastic "clear coat" on it. There are relatively few points you actually contact metal. The hitch area is one, the door area is another. The most likely way to get zapped is with your feet on the ground and grab the "hot" stuff.

There is indeed another possibility - grandpa's house may not be grounded properly (yikes !!). You can have the whole house wired up so in the house "ground is all the same". You will not quickly notice any issues. The connection from what the house calls ground to the "earth outside" may or may not be a solid one. All will seem ok, but it's not. Yes, that's the abridged version, there are a few other boring details. It might well be worth having an electrician stop by and take a look.

Bob

[Al and Missy]

When replacing my entrance conduit the electrician found a loose connection to the ground rod from my service panel, so bad grounds can happen.

Another possibility (albeit somewhat remote) is that the ground potential at the trailer may be different than the ground potential where the house is grounded. Several things could cause that. The only solution for that is to drive a ground rod at the trailer and connect it to the trailer frame. When I was designing and building military communications shelters it was required to drive a ground rod at the shelter and the generator supplying it.

Al

[Mollysdad]

I chased a slight tingle in my home. I bought a $4 tester at the big box store and the outlet tested good. I finally hired an electrician, and in 15 minutes he traced it to a power strip behind a bookcase (isn't it always?) that had hot and neutral reversed.
I forgot about the power strip. The advantage of a professional is that he doesn't come with preconceived notions.

Originally Posted by Al and Missy

The only solution for that is to drive a ground rod at the trailer and connect it to the trailer frame.

Since the ground rod at the trailer is some distance from the ground rod at the power box, it may prevent you from a deadly shock, but any electrical equipment will still see that as a ground fault, and there may be enough resistance to create a voltage difference. (to neutral)
I did exactly that to ground a UPS for my computer, and it still shows "fault". The two ground rods are probably 50' apart and both in ground water here.

Originally Posted by TG Twinkie

The neutral and ground should not be bonded.

Every breaker panel I've seen on homes have the ground and neutral connected.


Do you have any other ground paths to your trailer? Coax for cable? AC cord with the ground lug broken off? These are the easy path for a shock.

[uncle_bob]

Hi

The "ideal case" would be to bond the ground on everything to a single point. That may not be wise or even legal (per code). If you are putting in gear that takes lightning hits on a regular basis (several an hour in a storm) you do what you have to do. In a home it's not quite that simple. The rules are there for a reason, there are many ways for things to go wrong.

If you *really* want to see fun with grounds, take a look at your typical modern farm. Big electrical loads in multiple buildings. Each wired in years apart from the others. All out on the end of a big long power feed. ... hmmm .. why does Susie the Cow kick when we hook up the milking machine ... hmmmm ... ouch ....

Boats have a similar issue with grounds and shore power. Since you have water "right there" the risk is pretty high. Big heavy isolation transformers are one solution there. Even then sneak paths are a problem.

Best to get a pro involved if you note an issue. Compared to a trip to the hospital (or worse) they are dirt cheap.

Bob

[ITSNO60]

Earth grounding at the levels of voltage being discussed here by the use of ground rods etc. does nothing to mitigate a ground fault, as Mollysdad points out with his ground rod experiment, the earth's resistance is too great to carry enough current to do anything, let alone trip a circuit breaker. In the case of an uncleared fault the ground rod and everything connected to it simply becomes energized, a very dangerous situation. Ground rods were never intended to clear faults in household systems. That would be the job of the grounded conductor, or the neutral as some call it. The grounded conductor, not to be confused with the grounding conductor, is solidly connected to the center tap of the transformer. When a ground fault occurs, current travels along the grounding system back to the main disconnect where the grounding system is bonded to the grounded, or neutral conductor. This allows massive current to flow which in turn overloads the over current protective device (circuit breaker) causing it to open, which removes the ground fault.

Grounding is a largely confusing and mis-understood subject, even by many "electricians". Anyone who has a firm understanding of Ohm's law can see how a ground rod is useless at clearing faults of household voltage levels. The ground rods at your house are there for lightning and for faults on the grid caused by transmission lines contacting secondary lines.

[ITSNO60]

Originally Posted by TG Twinkie

The neutral and ground should not be bonded except at the service entrance where it is required.

fixed it for ya