Camper shocking me.

Anything electric, AC or DC

Re: Camper shocking me.

Postby H.A. » Sat Jul 23, 2016 7:11 pm

Well, you found a problem.
Lack of a grounding connection does not explain the initial situation of an energised chassis.
A grounding conductor or not, chassis should never become energised. Grounding only renders it safe in the event it does become energised.

Lacking proper test instruments,
it would be interesting to see what happens if plugged into a correctly wired GFCI receptacle.
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Re: Camper shocking me.

Postby Camp4Life » Tue Aug 16, 2016 10:24 am

In a trailer, I wouldn't advise using the frame as a ground (if that's what you're doing). You should run all +positive and -ground wires to everything DC, ESPECIALLY if you plan on adding AC(shore power/inverter) in the future where you will want to ground that. I don't recommend grounding both AC and DC to the trailer chassis/frame. Nightmares could ensue.

Also, this is sometimes just a case of static buildup which can occur in cars as well, especially in dry climates.

A simple fix is to keep the chassis grounded. Of course it never is, because rubber tires are not good conductors. You can however buy grounding straps for cheap.

They look like so:
Image

Some have reflectors, some don't, some are black, etc. Some have pin inserts and some are just braided conductors. Just attach it to a bare part of the frame or axle and then paint over it (Where you attached it, not the whole thing!). This allows any static/electrical buildup to discharge into the ground and keeps you from getting shocked. And because it's not solid, it won't drag down the road when you're on the highway because the wind keeps it lifted off the ground and it only touches ground when you stop or when you're driving really slow.
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Re: Camper shocking me.

Postby Mike S » Tue Aug 16, 2016 12:35 pm

It would be interesting to see what happened when you plug into a GFCI outlet. In fact, you should have GFCI protection on-board your trailer anyway. You should also go through each AC circuit branch and your distribution box to check for shorts. Do you have a multi meter? You can get a basic one at the hardware store for $30. Multimeters not only check voltage on AC and DC circuits, they also help you determine exactly where you short is.

I had a situation last year in which my trailer kept tripping GFCI outlets. I never got a shock or smelled any burning wires. Upon inspection of my AC distribution box, I found that I had a neutral to ground short. This type of short normally wouldn't cause any problems, but in the case of a malfunction, the ground circuit wouldn't wok properly. Different situation, but it was an example of a problem being detected by a GFCI outlet.

Good luck and happy trailering.
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Re: Camper shocking me.

Postby bdosborn » Tue Aug 16, 2016 8:19 pm

Camp4Life wrote:In a trailer, I wouldn't advise using the frame as a ground (if that's what you're doing). You should run all +positive and -ground wires to everything DC, ESPECIALLY if you plan on adding AC(shore power/inverter) in the future where you will want to ground that. I don't recommend grounding both AC and DC to the trailer chassis/frame. Nightmares could ensue.


That's interesting, what kind of nightmares would ensue?
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Re: Camper shocking me.

Postby Camp4Life » Wed Aug 17, 2016 11:44 am

bdosborn wrote:
Camp4Life wrote:In a trailer, I wouldn't advise using the frame as a ground (if that's what you're doing). You should run all +positive and -ground wires to everything DC, ESPECIALLY if you plan on adding AC(shore power/inverter) in the future where you will want to ground that. I don't recommend grounding both AC and DC to the trailer chassis/frame. Nightmares could ensue.


That's interesting, what kind of nightmares would ensue?
Bruce


This all depends on what you're putting into your trailer (Inverter, converter to charge your battery, etc) and whether or not you know what you're doing, and if you're sure that where you plug into for AC is wired correctly and has a good ground. You also don't want to accidentally bypass a transformer's functions with improper wiring. Personally, I would do 2 isolated systems and ground nothing to the chassis, and just ensure with my little AC tester that what I'm plugging into is wired correctly. If the ground is absent in the source, this is when a ground spike comes in handy that you can tie into your AC ground wiring. This is something we do in the Army with 3-foot spikes and a good copper wire in isolated locations.

First of all, and the most harmless things from sharing an AC/DC ground would be noise in your DC system coming from a dirty AC source. This can cause problems if you have a radio, but can also cause problems with sensitive electronics like charging systems, converters, phone chargers and solar controllers.

You also have the possibility that maybe your AC source isn't wired/grounded properly. If for some reason your trailer frame becomes energized, and you're standing outside and touch it, the electricity will go through the path of least resistance (you) to get to ground, which can be deadly. If your AC wiring is completely isolated, then you don't have to worry about this ever, unless you do something unsafe like place a bare heating element onto a metal part of your trailer framing.

You may also somehow get your AC hot in contact with your +12v by incorrectly wiring an inverter or converter (hey, it can and has happened!), or arcing from a water leak, put a screw through them, or any number of things. If this happens and your AC and DC are sharing ground, now the AC circuit has a path to ground through your DC wiring, and you could have 110v running through your 12v inverter, lights, solar charger and battery. If you're lucky, the AC source will trip fast enough. Otherwise, you can kiss all those devices goodbye, and pray that your battery didn't do something nasty :cry:

I don't mean to scare people! :frightened: I'm just throwing out some caution here, especially for anyone who isn't sure what they're doing. Using a common ground in 12v applications is partially a cost savings because you only need half the wiring, and it's less to wire up. If you've ever taken an RV apart, you'll see that pretty much every light, fan, etc runs post a positive and negative wire. AC grounding in an RV can go both ways though. I'm just all about safety and always taking the safest route...
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Re: Camper shocking me.

Postby bdosborn » Wed Aug 17, 2016 7:51 pm

Camp4Life wrote:This all depends on what you're putting into your trailer (Inverter, converter to charge your battery, etc) and whether or not you know what you're doing, and if you're sure that where you plug into for AC is wired correctly and has a good ground. You also don't want to accidentally bypass a transformer's functions with improper wiring. Personally, I would do 2 isolated systems and ground nothing to the chassis, and just ensure with my little AC tester that what I'm plugging into is wired correctly. If the ground is absent in the source, this is when a ground spike comes in handy that you can tie into your AC ground wiring. This is something we do in the Army with 3-foot spikes and a good copper wire in isolated locations.


A ground rod does not keep you safe from touch potential and here's why:

ECM Linky

You need a ground wire to conduct return current back to the AC source and trip the circuit breaker. GFCI is the best option for personnel protection if the ground wire is missing.

First of all, and the most harmless things from sharing an AC/DC ground would be noise in your DC system coming from a dirty AC source. This can cause problems if you have a radio, but can also cause problems with sensitive electronics like charging systems, converters, phone chargers and solar controllers.


Only if you tie the neutral to the ground in your trailer, which you would never do if you know what you are doing. The ground wire only carries current during a fault, the remaining 99.9999% of the time it's de-energized. And BTW, I have all those systems you mentioned in my trailer and without any noise issues from a well grounded frame.

You also have the possibility that maybe your AC source isn't wired/grounded properly. If for some reason your trailer frame becomes energized, and you're standing outside and touch it, the electricity will go through the path of least resistance (you) to get to ground, which can be deadly. If your AC wiring is completely isolated, then you don't have to worry about this ever, unless you do something unsafe like place a bare heating element onto a metal part of your trailer framing.


That's why a lot of us carry receptacle testers, to make sure the campground hot and neutral aren't reversed wired and the ground is good. If a hot wire does come in contact with the frame, not having a ground guarantees that the frame will remain energized until someone touches it, and the breaker probably won't trip during the fault as people have a relatively high resistance to ground. You're better off having the frame grounded to ensure the AC circuit breaker trips if it gets energized somehow.

You may also somehow get your AC hot in contact with your +12v by incorrectly wiring an inverter or converter (hey, it can and has happened!), or arcing from a water leak, put a screw through them, or any number of things. If this happens and your AC and DC are sharing ground, now the AC circuit has a path to ground through your DC wiring, and you could have 110v running through your 12v inverter, lights, solar charger and battery. If you're lucky, the AC source will trip fast enough. Otherwise, you can kiss all those devices goodbye, and pray that your battery didn't do something nasty :cry:


The battery isn't the return source for the AC system, assuming you've kept your neutral isolated. Not having the AC ground means the system would be energized, without any current flowing, until there was a return path (hopefully not through you). An AC and DC ground wire to the frame would ensure the circuit tripped if a 120V wire hit the DC system.

I don't mean to scare people! :frightened: I'm just throwing out some caution here, especially for anyone who isn't sure what they're doing. Using a common ground in 12v applications is partially a cost savings because you only need half the wiring, and it's less to wire up. If you've ever taken an RV apart, you'll see that pretty much every light, fan, etc runs post a positive and negative wire. AC grounding in an RV can go both ways though. I'm just all about safety and always taking the safest route...


I agree that using the frame as a DC return path is sketchy and is the source of most problems with trailer lights. However, there's a lot of good reasons you should bond the trailer frame to the AC ground wire.

You've stumbled into a highly debated subject here on the forum. Hang on for about 5 more posts debating the merits of frame grounding. ;) :roll:



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Re: Camper shocking me.

Postby H.A. » Thu Aug 18, 2016 12:43 am

You've stumbled into a highly debated subject here on the forum. Hang on for about 5 more posts debating the merits of frame grounding.

Its only debated by folks with Shadetree understanding of electrical world around them.
Properties of electrical energy are hard facts, there is nothing to debate.
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Re: Camper shocking me.

Postby aggie79 » Thu Aug 18, 2016 8:30 am

Camp4Life wrote:A simple fix is to keep the chassis grounded. Of course it never is, because rubber tires are not good conductors. You can however buy grounding straps for cheap.


When I get to a campsite, I let my safety chains lay on the ground to act as a grounding strap.
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Re: Camper shocking me.

Postby Dale M. » Thu Aug 18, 2016 8:41 am

Funny thing is telecommunications companies have 1 week course on how to ground things.... And with all the discussion here, everyone has their own opinions and every one here has at least one or two facts wrong......

The major issue with all this discussion is not really whether AC and DC side are common bonded to a single ground plane such as the trailer chassis.... IF you understand how electricity works (high school science level) you should not get into any trouble with grounding...

Only real issue is IF TRAILER IS WIRED CORRECTLY is that the SHORE POWER you plug into is wire CORRECTLY and your UMBILICAL cord is good..........

And as for the ground gurus that state to not bond ground and AC neutral together, EVERY recently build house in US has a drive ground rod bonded to the neutral in its entrance panel....I am not saying to drive a ground rod at every camp site WHAT I AM SAYING is verify the receptacle you are plugging into (shore power) is wired correctly....

Also I have to say HUH when people say not to trust chassis for ground... 100,000,000 vehicles (trucks, car, trailers) use chassis ground with very rarely a problem... Yes mounting lamps on wood or on wood construction with metal sheeting over it can be a problem ... But that is why you run ground bond wire to chassis... Just ask me I build fiberglass bodied kit cars... you want to know what ground problems are just build a fiberglass kit car...

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Hope I have not ruffled to many feathers but some of the theory spoken here just does not work, is not safe and that is why I just sort of stay away from all this discussion...

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Re: Camper shocking me.

Postby Camp4Life » Thu Aug 18, 2016 10:02 am

bdosborn wrote:
Camp4Life wrote:This all depends on what you're putting into your trailer (Inverter, converter to charge your battery, etc) and whether or not you know what you're doing, and if you're sure that where you plug into for AC is wired correctly and has a good ground. You also don't want to accidentally bypass a transformer's functions with improper wiring. Personally, I would do 2 isolated systems and ground nothing to the chassis, and just ensure with my little AC tester that what I'm plugging into is wired correctly. If the ground is absent in the source, this is when a ground spike comes in handy that you can tie into your AC ground wiring. This is something we do in the Army with 3-foot spikes and a good copper wire in isolated locations.


A ground rod does not keep you safe from touch potential and here's why:

ECM Linky

You need a ground wire to conduct return current back to the AC source and trip the circuit breaker. GFCI is the best option for personnel protection if the ground wire is missing.

First of all, and the most harmless things from sharing an AC/DC ground would be noise in your DC system coming from a dirty AC source. This can cause problems if you have a radio, but can also cause problems with sensitive electronics like charging systems, converters, phone chargers and solar controllers.


Only if you tie the neutral to the ground in your trailer, which you would never do if you know what you are doing. The ground wire only carries current during a fault, the remaining 99.9999% of the time it's de-energized. And BTW, I have all those systems you mentioned in my trailer and without any noise issues from a well grounded frame.

You also have the possibility that maybe your AC source isn't wired/grounded properly. If for some reason your trailer frame becomes energized, and you're standing outside and touch it, the electricity will go through the path of least resistance (you) to get to ground, which can be deadly. If your AC wiring is completely isolated, then you don't have to worry about this ever, unless you do something unsafe like place a bare heating element onto a metal part of your trailer framing.


That's why a lot of us carry receptacle testers, to make sure the campground hot and neutral aren't reversed wired and the ground is good. If a hot wire does come in contact with the frame, not having a ground guarantees that the frame will remain energized until someone touches it, and the breaker probably won't trip during the fault as people have a relatively high resistance to ground. You're better off having the frame grounded to ensure the AC circuit breaker trips if it gets energized somehow.

You may also somehow get your AC hot in contact with your +12v by incorrectly wiring an inverter or converter (hey, it can and has happened!), or arcing from a water leak, put a screw through them, or any number of things. If this happens and your AC and DC are sharing ground, now the AC circuit has a path to ground through your DC wiring, and you could have 110v running through your 12v inverter, lights, solar charger and battery. If you're lucky, the AC source will trip fast enough. Otherwise, you can kiss all those devices goodbye, and pray that your battery didn't do something nasty :cry:


The battery isn't the return source for the AC system, assuming you've kept your neutral isolated. Not having the AC ground means the system would be energized, without any current flowing, until there was a return path (hopefully not through you). An AC and DC ground wire to the frame would ensure the circuit tripped if a 120V wire hit the DC system.

I don't mean to scare people! :frightened: I'm just throwing out some caution here, especially for anyone who isn't sure what they're doing. Using a common ground in 12v applications is partially a cost savings because you only need half the wiring, and it's less to wire up. If you've ever taken an RV apart, you'll see that pretty much every light, fan, etc runs post a positive and negative wire. AC grounding in an RV can go both ways though. I'm just all about safety and always taking the safest route...


I agree that using the frame as a DC return path is sketchy and is the source of most problems with trailer lights. However, there's a lot of good reasons you should bond the trailer frame to the AC ground wire.

You've stumbled into a highly debated subject here on the forum. Hang on for about 5 more posts debating the merits of frame grounding. ;) :roll:

Bruce


I agree with you Bruce, that grounding the AC to the frame is good practice, as long as you're always sure that what you're plugging into is wired properly and that you always check it first with a tester. Problem is that not everyone knows to do this, and some don't care to bother checking. I hope that people who are wiring up their trailers check resourceful sites like this to get the proper information. But I do also know people who just dive into things and think "this makes sense, connect this to that and I'm done." but they don't even know what a GFCI is, or that there are things you need to check and so on... My biggest point, which I have posted in many threads, is to not ground DC to the frame.
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Re: Camper shocking me.

Postby bdosborn » Thu Aug 18, 2016 6:59 pm

Dale M. wrote:And as for the ground gurus that state to not bond ground and AC neutral together, EVERY recently build house in US has a drive ground rod bonded to the neutral in its entrance panel....


Yup, that's required by code. But there's only supposed to be ONE neutral-ground bond per service (only at the service entrance), with a ground rod, and there are really good reasons for keeping the neutral and ground completely isolated everywhere else. Here's one:

What we want is for current to leave the Service Panel’s hot leg (i.e., the breaker), to travel to and through the load, and to make its way back via the neutral, without having the option of taking any other path. If we connect the grounded conductor (i.e., neutral) to the equipment grounding conductor (i.e., green wire) anywhere downstream of the Service Panel (e.g., bonding them inside a sub-panel or at a receptacle), then the current will have two paths to take: the neutral and the ground wire. And it will take both paths. The neutral is out of reach of human hands; the ground wire is not, since it connects to external metal parts. Therefore, if a human touches the metal parts, the current will have three paths back to its source: the neutral, the ground wire, and the human. And it will take all three paths.

So don't connect the neutral and the ground wire together anywhere in your trailer's AC system. :thumbsup:

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Re: Camper shocking me.

Postby Dale M. » Thu Aug 18, 2016 9:15 pm

bdosborn wrote:
Dale M. wrote:And as for the ground gurus that state to not bond ground and AC neutral together, EVERY recently build house in US has a drive ground rod bonded to the neutral in its entrance panel....


Yup, that's required by code. But there's only supposed to be ONE neutral-ground bond per service (only at the service entrance), with a ground rod, and there are really good reasons for keeping the neutral and ground completely isolated everywhere else. Here's one:

What we want is for current to leave the Service Panel’s hot leg (i.e., the breaker), to travel to and through the load, and to make its way back via the neutral, without having the option of taking any other path. If we connect the grounded conductor (i.e., neutral) to the equipment grounding conductor (i.e., green wire) anywhere downstream of the Service Panel (e.g., bonding them inside a sub-panel or at a receptacle), then the current will have two paths to take: the neutral and the ground wire. And it will take both paths. The neutral is out of reach of human hands; the ground wire is not, since it connects to external metal parts. Therefore, if a human touches the metal parts, the current will have three paths back to its source: the neutral, the ground wire, and the human. And it will take all three paths.

So don't connect the neutral and the ground wire together anywhere in your trailer's AC system. :thumbsup:

Bruce


You are correct, I was trying to make point that "ground" and AC systems neutral should be as same potential, BUT I really think the GROUND from power pedestal should be extended to trailer chassis and skin.... That is want started this whole discussion, first poster actually had bad cord I believe but it should not have shocked him.........

First thing to do when arriving at camp site is check/test the receptacle on pedestal for proper wiring if test shows bad DO NOT PLUG IN , go to office and notify management pedestal has problem and request a different site....... IF test shows good, then plug in and immediately test receptacle in trailer... IF test shows good then all is well, if test shows bad, immediate suspect your umbilical cord has a fault or something came loose while trailer was in motion......

Again invest $10 becasue it just may save your life...

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This one will test GFI circuits...

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This ain't a bad thing to have along either...

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Re: Camper shocking me.

Postby bdosborn » Fri Aug 19, 2016 9:10 am

Dale M. wrote: You are correct, <snip>


Of course I am, I'm an engineer. I don't make mistakes, I make revisions... ;)

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Re: Camper shocking me.

Postby Dale M. » Sat Aug 20, 2016 8:11 am

bdosborn wrote:
Dale M. wrote: You are correct, <snip>


Of course I am, I'm an engineer. I don't make mistakes, I make revisions... ;)

Bruce


And for 38 years in work world I had to deal with your revisions.... :? :? :? :?

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