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Author Topic: ELECTRIC WOE'S  (Read 1564 times)
larryh
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« on: December 03, 2006, 07:11:27 PM »

As you know I'm in the middle of doing the conversion on my 4905 and had a friend stop by the other day and was working on a leak in the water tank piping. The ground was damp where I had drained some water out of tank and his dog came up and sniffed the door frame and he had a shocking experience.

It seems the electrican who started the wiring had wired the coach the same as any house. The ground wire and the neutral wire in to the ground buss bar and which I continued on with.

Well it turns out on our coaches we have to have a isolated ground from the neutral wire. I have taken all the ground wires off and connected into a lug and folded back out of the way

The dog will not come within 30 feet of bus now I'm sorry for him but better I seen him than me get it.

LarryH

PS flame protection suit on now fire away
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Dallas
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« Reply #1 on: December 03, 2006, 07:15:50 PM »

Larry, I'm glad you got that fixed!
Now you can use GFCI outlets in the required areas.

Did you get a new isolated bar for your breaker box or build one like we talked about?

One thing I was thinking about:

It's a good thing the dog wasn't peeeing when it completed the circuit!  Shocked Shocked Shocked Shocked Shocked
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gus
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« Reply #2 on: December 03, 2006, 07:24:16 PM »

Larry,

Exact same story on my 4104 when I got it except without the dog!

I, too,  made an isolated ground and am sure glad I found out about it on this board before I got shocked. This board is great!!

I think a bunch of bus nuts make the same mistake thinking a house electrician knows his stuff.
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larryh
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« Reply #3 on: December 03, 2006, 07:31:46 PM »

Dallas after receiving the shock he peed alright for about 2 min he was a hurting pup. I couldn't find a bar here in Quartzsite so I just put them all in a lug and tightened them up and the harware store has orderd a bar for me.

LarryH
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Savvy ponderable:
A cowboy's only afraid of two things:
havin' ta walk,
and the love of a good woman.
"This posting was generated using an environmentally friendly, self contained flatulence generator, therefore no fossils or neutrons were harmed in the creation of this posting.


Quartzsite,
JerryH
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« Reply #4 on: December 03, 2006, 08:02:50 PM »

Larry:

I had somewhat of a similar thing.  Bought our MC-8, done by Custom Coach originally.  But (I think) previous owner re-wired the shore cable, which I NEVER checked before plugging it in.  Well, he had the neutral back to the chassis.  I touched the exterior of the coach while entering it and got a tickle from it.  Told the kids to get away from the bus while I went to unplug it. 

So, anyone buying a used coach, wired by others -- CHECK IT OUT.  Even if it's done by a professional converter, please check your shore cables just in case a previous owner made some not-so-cool changes.  Also check with a multi-meter to check continuity between neutral and the chassis.

Just my $0.02,
Jerry H.
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Danny
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« Reply #5 on: December 03, 2006, 08:08:39 PM »

I am wiring my bus as we speak.  You guys are talking about having a separate ground and neutral bar in the electrical panel - right? 

Thanks,
Danny
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« Reply #6 on: December 03, 2006, 10:01:43 PM »

Yes Danny it is a seperate bar and the netural must be isolated from the ground,on mine the netural bar is mounted on plastic isolators and the ground bar is mounted directly to the box and grounded to the chassie Mike
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JackConrad
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« Reply #7 on: December 04, 2006, 04:53:58 AM »

As a safety check, pour a little water on the ground then, with the shore power connected, use a multimeter to check for voltage between the bus frame and the wet ground. Jack
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« Reply #8 on: December 04, 2006, 05:47:29 AM »

If you have the neutral and ground bonded at two locztions, it is possible to get ground currents. You can have this situation at your home if more than one house is on the distribution transformer and one house draws a large current relatiive to the other. This ground current is usually less than five volts and is not harmful.

If you have any significant voltage appearing on the shell of a RV, it is because the neutral and hot wires are reversed somewhere in the RV or in the distribution system.

If your shore cord or the outlet in the shore pedestal is conneted backwards, you are coonecting the hot wire directly to the shell of the RV if the neutral and ground are bonded in the RV panel. Since the RV sits on rubber tires, you complete the circuit when you touch it. There is no hazard unless there is wiring mistake. Make sure that there is no mistake in your RV and it is good practiice to always check a shore outlet with one of the testers that check for correct wiring.

This is not to say that Larry's dog would not get a surprise from a low voltage ground cureent when urinating on the bus, but I think he has an additional problem of incorrect or faulty wiring.
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larryh
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« Reply #9 on: December 04, 2006, 06:39:13 AM »

Stan

That was my first impression and all outlets were checked with a tester and all were ok no red lights on and I took off all covers and neutral wire was on proper side. I did not the plug in park Huh

Thanks LarryH
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Savvy ponderable:
A cowboy's only afraid of two things:
havin' ta walk,
and the love of a good woman.
"This posting was generated using an environmentally friendly, self contained flatulence generator, therefore no fossils or neutrons were harmed in the creation of this posting.


Quartzsite,
Len Silva
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« Reply #10 on: December 04, 2006, 06:42:29 AM »

Stan,

I agree, correcting the bonded neutral did not correct the problem, only provides a measure of protection. †There is still some "leakage" to the chassis somewhere in the coach. †In addition, the protection provided is only as good as the grounding at the park outlet, which can be difficult to verify.

A simple way to check is with an ohmmeter at the plug, connected between neutral and ground on it's highest scale. It should read ∞ (infinity). †If it reads low (say 0 to 5 Ω) the neutral is probably bonded. Anything less than ∞ indicates a connection to ground somewhere in the coach.

Begin by turning off circuit breakers and/or unplugging equipment, even disconnecting wires if necessary to isolate the offending circuit. This is something that should be checked on a regular basis.

Tripping a GFI breaker at the pedestal is also an indication of a problem in your bus.

I like Jack's idea of checking from the bus chassis to ground. †That would show up a bad ground connection at the pedestal.

Len
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« Reply #11 on: December 04, 2006, 09:41:37 AM »

Another thing you should do, is remove the power source and then pull ALL of the neutral branch wires off of the panel and check continuity of each to the ground bar AND their hot wire (connected to the breakers, which should be turned off for these tests). There could be a bonded or reverse-polarity connection somewhere in your branch circuit and I've found this technique to be the quickest/ easiest way to find the offending one(s).

When I bought my 4106, I kept tripping GFCIs at CGs, even though I had an isolated neutral/ ground. One day, I got shocked when touching the bus.   Shocked  When I performed then the above test, I found that my front A/C neutral wire showed continuity to ground (probably a frayed connection touching the bus frame), leading to a dangerous short-circuit.

Also, some elec. panels have a bonding screw that MUST be removed.

And the bus chassis, AC grounds, AND DC negative wires should ALL be tied together with big wires and a big, clean bolt.

HTH,
Brian B.
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Brian Brown
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« Reply #12 on: December 04, 2006, 10:12:08 AM »

Since some people want to get into the testing of their coach electrical system, there is only one approved way. That is a Hipot test, which is required on all S&S RVs before they leave the factory. 

The Hipot test applies a minimum of 600 volts DC to both the hot wire to ground and the neutral wire to ground and there whould be zero leakage. An ohmneter test or a voltmeter test to wet ground will not show up any type of voltage breakdown that occurs at 120 or 240 volts AC.

One should not apply this test without some technical knowledge on what electronic components could be damaged by the test. It may be necessary tp remove the components before doing the test.

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