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sajohnson's avatar
sajohnson
Explorer
Feb 05, 2013

RV Grounding and Safety

Recently, on a Yahoo group devoted to the Winnebago View/Itasca Navion, a member posted about a potentially deadly experience he had. In the interest of safety I thought I should post it here:

~~~~~

Night before last, when we docked for the night, I did my usual step of plug in the electric first, then the TV cable. I accidentally brushed the cable outer housing against the square electric box and a huge spark occurred. I immediately unplugged the cord from the power pole and discovered the pole breaker was tripped. Reset breaker and tried again. Everything seemed OK.

Went inside coach and in a short time, smelled electric smoke. Rushed outside and saw a trace of smoke coming from the square electric box below the generator plug. Killed power and unplugged from the plug. Smoke stopped.

Removed the cover from the square box (where the coach plug goes into the inside electric system). What I found scared the begeebers out of me! The black wire had apparently been pressed HARD up against the cover. Over time, the insulator/connector had abraided against the metal cover until it wore through and shorted out. The spark was the result of the metal box being "hot" with the full 30amp potential waiting for a ground. That could have been ME if the cable had not sparked and warned me! Fortunately, this was caught in time to prevent a fire or personal injury through electrocution.

I post this as an advisory for all on the group. We have used Geovanii for 5 1/2 years, spent more than 500 nights in it, and suddenly we have a worn through electrical connector (wire nut)! Could happen to anyone!

I recommend a visual inspection on this connector box. Some models will be easier than others. To do a quick visual inspection, first REMOVE ALL ELECTRICAL POWER FROM COACH. This means unplugging the electrical cord from any source of power,either internally or externally, such as either a power pole, generator or inverters. (Those with inverters installed should make sure no power is going to the system!) Next, remove the 4X4 box cover from the connector box (loosen two screws - do not have to be removed) check the wire nuts in this box for abraiding and tightness. If all is as it should be, replace the box cover, making sure none of the wires are a pushing against it. You are done!

In the event you see evidence of damage, check the wires to make sure they are not damaged and replace the wire nuts and make sure they are not touching the box or cover when you replace the cover.

IF YOU ARE NOT COMFORTABLE WITH ELECTRICAL WORK, GET AN ELECTRICIAN TO CHECK THE BOX FOR YOU!

This is not intended to be a step by step instruction checklist! It is a rough guide to help show you what and how i found my problem. YMMV!

I feel like we dodged a big bullet on this one. Just a heads up for everybody!

~~~~~

Big bullet indeed. This man could easily have been electrocuted.

In addition to the recommendations in the above post, I would suggest that it is worthwhile to check every rig for proper grounding of all electrical boxes, enclosures, and appliances -- as well as doors, door frames, grab handles -- anything that might potentially become energized and could be touched by someone.

I immediately checked my View and found that the electrical boxes in the electric cabinet, the enclosure around the circuit breakers, the stove, the microwave, and the door, door frame, and grab handle are all grounded. The sinks are not, but are unlikely to become energized.

Even if the wiring was done correctly at the factory, the vibration that it is subjected to can cause failures.

It doesn't take more than a few minutes to check and may save save your life or the life of a loved one.
Class C

11 Replies

  • sask66's avatar
    sask66
    Explorer
    Jun 12, 2013
    Not exactly on the topic but I had an experience with my unit this past weekend. Had it parked on my yard and ran my shoreline cord under the unit into a receptacle in my garage while the jacks were down. Retracted the jacks later because of a lot of rain to avoid soft ground and yard damage. When I unplugged to put cord back into storage it had got caught in the jack pad and ram and pinched the cord to a point where I had to cut cord and repair. Moral of the story: don't run cord under unit with jacks, or check position of cord to prevent problems when retracting.
  • Harvey51's avatar
    Harvey51
    Explorer
    Jun 11, 2013
    Thank you for those posts, SAJohnson! Most informative.

    I'm getting a little careless with electricity in my senior years, partly because it doesn't seem to shock me very much anymore. My skin must be drying out. I am upgrading to GFI outlets in my garage anyway. What a great thing GFI is. Too bad the GFI breakers for breaker boxes are so expensive - nearly $100 here.
  • sajohnson's avatar
    sajohnson
    Explorer
    Jun 11, 2013
    Quick story related to the above posts.

    We were staying at state park recently in IL. Since I haven't purchased a surge suppressor yet I'm in the habit of using a 120V/20A outlet tester along with a 20A>30A outlet adapter to check the pedestal wiring. The 30A outlet was ok, but out of curiosity I checked the 20A outlet -- the hot and neutral wires on it were reversed!

    Needless to say, that can be very dangerous. My understanding is that in some rigs the neutral is connected to the frame and/or outer shell. If that were the case, the frame and/or 'skin' of the rig would become hot when its plugged into that shore power outlet.

    I notified the camp hosts and they had the electrician repair it immediately (which surprised me).

    Anyway, just a reminder to always check your shore power supply.

    Equally important is confirming that any exposed metal that is supposed to be grounded, is. Even the best surge suppressor cannot check for proper grounding (see above).
  • sajohnson's avatar
    sajohnson
    Explorer
    Feb 08, 2013
    I need to correct a statement I made.

    When I said that some pricier units have GFCI protection, I based that on a chart I found at RV Upgrades. After speaking with Jeff at Progressive Industries (PI), I realized that the chart is misleading -- it has one row labeled: "Ground Fault Shutdown". To me, that implies GFCI protection. One of the less expensive units, the Surge Guard #44740, does have GFCI protection, but the others (if they have anything at all) have 'open ground protection', but _not_ GFCI.

    That is too bad, since GFCI would provide protection from electrocution in situations like the View/Navion owner experienced -- an ungrounded electrical box or appliance becoming hot (energized) with 120V.

    Jeff confirmed that there is no surge protector that can detect faulty wiring "behind it" (downstream) in the coach. There is also no way for a surge protector to detect ungrounded boxes, appliances, or pedestals. Some can detect if the _outlet_ itself is grounded -- but there's no way for them to tell if the box or pedestal (or anything inside the RV) is grounded.

    He and I agreed that the situation described in the OP is probably rare, but it is also potentially deadly. Since most surge protectors do not have GFCI protection, it is very important to confirm proper grounding of any exposed metal that could become energized.

    Jeff told me about a tragic incident in which a RV owner's granddaughter was electrocuted after returning to the RV from swimming. She was wet and standing on wet ground. She touched something that was ungrounded and had become hot (the shell of the RV I think) and was killed. I think in that case the problem was with the shore power -- the ground was open (no ground) and the hot and neutral were reversed. The same thing could happen if the RV frame was not properly grounded -- even if the best surge protector available indicates that everything is ok.

    Better safe than sorry.
  • Coach-man's avatar
    Coach-man
    Explorer
    Feb 06, 2013
    sajohnson wrote:
    Coach-man wrote:
    A inexpensive electrical checker can be purchased, (at camping world & elsewhere), you simply plug it into your outlets, and the lights will indicate, ok, reversed polarity, no ground condition. I also purchased a "surge protector with meters, that basically did the same for the main power cord. In 12 years of camping, I only had one problem with the box being wired incorrectly, but then again it only takes one time to get electrocuted!!


    These testers are great. I have one myself. They cost less than $10 and are quick and easy to use. No electrical knowledge necessary. Every RVer(and homeowner) should have one.

    The RV surge suppressors (SS) are also a very good idea. I don't own one yet but plan to buy one soon (we just got our View last summer). I'm currently researching them.

    Here's the problem:

    Neither of these devices can detect the lack of a ground connection on a box, enclosure, door frame, or appliance.

    What they _can_ detect is the lack of a ground connection at an outlet -- but only the round receptacle for the ground prong on the plug. The _box_ or _pedestal_ could have no ground and the tester or surge suppressor would have no way of knowing.

    In fact, the pedestal or outlet box could be energized -- it could have 120 volts on it -- and the surge suppressor or tester would not detect that!

    A surge suppressor's job is to confirm only that the incoming power is ok. The better ones check frequency, voltage, reverse polarity, no neutral, no ground, etc. However, the surge suppressor's job ends there. It has no way of knowing if the "downstream" wiring in the RV is ok, and it certainly can't detect that a hot wire has contacted ungrounded metal.

    As a practical matter, when an outlet is grounded, the metal box or pedestal usually is too. Even if the enclosure does not have a proper ground wire, it will _usually_ (read: I wouldn't bet my life on it) be grounded through the screws that attach the outlet to the box.

    In the case above (see OP) it was the junction box inside the electric cabinet that was hot (the generator outlet box was grounded). The owner never actually posted anything about the ground (or lack thereof). He just mentioned finding the wire nut worn through allowing a bare hot wire to contact the box.

    Of course, that was only half of his problem. I suggested that he should confirm that the box is properly grounded but never heard back (as far as I recall). He may still have an ungrounded junction box. If so, the same problem could reoccur in the future.

    There was obviously no ground path for the 120V to follow. Had the box been grounded, there would have been a short circuit to ground and the 30A breaker on the pedestal would have tripped immediately. In fact, that's exactly what happened when he accidentally touched the box with the coax cable. That provided an alternate path to ground, through the coax shield. There was an arc, and the breaker tripped. Of course, he could have just as easily touched that box with his hand -- while standing on damp ground, or, while touching the _grounded_ generator outlet box next to it with his other hand and been killed instantly.

    One thing that I didn't realize that I discovered the other day is that some of the pricier surge suppressors have ground fault (GFI) protection. That is a _very_ good feature to have. It should protect anyone who accidentally becomes the path to ground for the 120Vac -- just like a GFCI outlet in a kitchen or bath.

    Of course, having GFI protection is no substitute for verifying that all (or almost all) exposed metal is grounded.

    It is quick and easy to do with a meter.


    GOOD info and point well taken, I guess you can not be to careful!
  • sajohnson's avatar
    sajohnson
    Explorer
    Feb 06, 2013
    Puttin wrote:
    We use these at work:



    And...it seems like a good time to mention this:

    http://www.arrisistore.com/product.php?pid=718844

    http://www.myrv.us/electric/


    The non-contact voltage detectors are very useful. There are many available by companies like Greenlee and Fluke. I have a Fluke that only cost about $20.

    Unfortunately, they can't be used to check for proper grounding.

    In order to check any particular piece of metal to see if it is grounded, you can:

    a) With power disconnected, use an ohmmeter and measure the resistance between that metal (an electrical box/panel, appliance, door frame) and a known good ground -- like the ground receptacle in a nearby outlet that's been tested. The resistance should be zero, or very close to it. The resistance between any two pieces of metal that are grounded should be close to zero.

    b) With power connected, use a voltmeter to measure the voltage present at an outlet. Measure between hot (the smaller slot) and neutral. It should be equal to the supply voltage (typically ~115-120Vac). Next measure from hot to ground -- you should get the identical reading (because the neutral and ground should be tied together at the source). Next measure from hot to the metal in question. If that metal is grounded, you should again get the same reading. If it is not grounded, you will measure something less, often about 50-70Vac.

    I used procedure b.

    ~~~~~

    Edit to add:

    In order to check the boxes in the electrical cabinet, I used an ordinary grounded extension cord and plugged it into the same outlet the RV's electrical cord was plugged in to. I used it in the same way as described above. Checked the voltage between hot>neutral; hot>ground; and then measured from hot to both boxes. In all cases the voltage measured was identical.
  • Puttin's avatar
    Puttin
    Explorer
    Feb 05, 2013
    We use these at work:



    And...it seems like a good time to mention this:

    http://www.arrisistore.com/product.php?pid=718844

    http://www.myrv.us/electric/
  • sajohnson's avatar
    sajohnson
    Explorer
    Feb 05, 2013
    Coach-man wrote:
    A inexpensive electrical checker can be purchased, (at camping world & elsewhere), you simply plug it into your outlets, and the lights will indicate, ok, reversed polarity, no ground condition. I also purchased a "surge protector with meters, that basically did the same for the main power cord. In 12 years of camping, I only had one problem with the box being wired incorrectly, but then again it only takes one time to get electrocuted!!


    These testers are great. I have one myself. They cost less than $10 and are quick and easy to use. No electrical knowledge necessary. Every RVer(and homeowner) should have one.

    The RV surge suppressors (SS) are also a very good idea. I don't own one yet but plan to buy one soon (we just got our View last summer). I'm currently researching them.

    Here's the problem:

    Neither of these devices can detect the lack of a ground connection on a box, enclosure, door frame, or appliance.

    What they _can_ detect is the lack of a ground connection at an outlet -- but only the round receptacle for the ground prong on the plug. The _box_ or _pedestal_ could have no ground and the tester or surge suppressor would have no way of knowing.

    In fact, the pedestal or outlet box could be energized -- it could have 120 volts on it -- and the surge suppressor or tester would not detect that!

    A surge suppressor's job is to confirm only that the incoming power is ok. The better ones check frequency, voltage, reverse polarity, no neutral, no ground, etc. However, the surge suppressor's job ends there. It has no way of knowing if the "downstream" wiring in the RV is ok, and it certainly can't detect that a hot wire has contacted ungrounded metal.

    As a practical matter, when an outlet is grounded, the metal box or pedestal usually is too. Even if the enclosure does not have a proper ground wire, it will _usually_ (read: I wouldn't bet my life on it) be grounded through the screws that attach the outlet to the box.

    In the case above (see OP) it was the junction box inside the electric cabinet that was hot (the generator outlet box was grounded). The owner never actually posted anything about the ground (or lack thereof). He just mentioned finding the wire nut worn through allowing a bare hot wire to contact the box.

    Of course, that was only half of his problem. I suggested that he should confirm that the box is properly grounded but never heard back (as far as I recall). He may still have an ungrounded junction box. If so, the same problem could reoccur in the future.

    There was obviously no ground path for the 120V to follow. Had the box been grounded, there would have been a short circuit to ground and the 30A breaker on the pedestal would have tripped immediately. In fact, that's exactly what happened when he accidentally touched the box with the coax cable. That provided an alternate path to ground, through the coax shield. There was an arc, and the breaker tripped. Of course, he could have just as easily touched that box with his hand -- while standing on damp ground, or, while touching the _grounded_ generator outlet box next to it with his other hand and been killed instantly.

    One thing that I didn't realize that I discovered the other day is that some of the pricier surge suppressors have ground fault (GFI) protection. That is a _very_ good feature to have. It should protect anyone who accidentally becomes the path to ground for the 120Vac -- just like a GFCI outlet in a kitchen or bath.

    Of course, having GFI protection is no substitute for verifying that all (or almost all) exposed metal is grounded.

    It is quick and easy to do with a meter.
  • Coach-man's avatar
    Coach-man
    Explorer
    Feb 05, 2013
    A inexpensive electrical checker can be purchased, (at camping world & elsewhere), you simply plug it into your outlets, and the lights will indicate, ok, reversed polarity, no ground condition. I also purchased a "surge protector with meters, that basically did the same for the main power cord. In 12 years of camping, I only had one problem with the box being wired incorrectly, but then again it only takes one time to get electrocuted!!
  • ScottG's avatar
    ScottG
    Nomad
    Feb 05, 2013
    With the sloppy fashion in which most RV's are built, this sort of thing doesn't surprise me at all. In my own case I found most of the wires going to the breakers were loose. Obviously the person assembling it just didn't care.

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