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Line voltage leak to trailer chassis


noteven
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In the course of getting the toyhauler ready for snowbird season I discovered a line voltage short to the trailer chassis / body. 

Trailer: Carriage C-Force 39SV2

Shore power: Marine type 50 amp connector with detachable cord. 

Onan 5500 generator

Situation: 

When connected to shore power, I measure 120v touching the test meter probe to the checker plate aluminum on the front drop of the trailer with the negative probe stuck in the damp soil beside the trailer. Tested both 50 amp cord with 50 to 30 to 15 adapter, and my 50 amp to 15 amp adapter. With both cords the stray voltage is present. 

When disconnected from shore power and generator is running no stray volatge is detected at the same location. 

When 12volt only no stray voltage is detected. 

Best ideas where to start fixing? 

Thanks

 

 

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12 minutes ago, J-T said:

What do you get when testing each leg (to ground) in the receptacle that the shore power cord would be plugged into.....

......looks like you found the issue faster than I could type

 

If you look at the article MrSeas posted the link to, I am getting 120v at the wrong side of the 15 amp receptacle. 

I'm at a private residence connected to 15 amp extension cord service to supply maintenance power for running furnace, charging batteries etc...

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5 minutes ago, Big5er said:

Ok, stupid question.....They make polarity testers/surge protectors. 

s-l500.jpg

 

s-l500.jpg

For those times when you only have 30amp power at the pedestal, would this still work using a 30amp adapter? Or do you need TWO of these, one in 30amp and one in 50amp? 

Me interested in the answer too....

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HOT SKIN is one of the most hazardous conditions in the RV world. Your barefoot grandchild standing on wet ground touches the RV !!!!!!!!!!!!!!!!!

 Id start by FIRST insuring the wiring and polarity is correct at the service outlet (no reversals !!!),,,,,,,,,,,,,,,,,,,And if so, then insure any cords and their plugs and receptacles and/or adapters are all wired correct (again no reversals) ,,,,,,,,,,,,,,,,,And if so then the incoming wiring at the RV main distribution panel is correct,,,,,,,,,,,,,,,,,,,Then insure in the RV main panel the Neutral Buss and Equipment Ground Busses are separate and electrically insulated and isolated from each other,,,,,,,,,,,,,,,Then insure the panels frame and the RV iron frame is bonded to the Equipment Ground Buss BUT NOT THE NEUTRAL...........Then insure there's no hot line shorts perhaps getting to the RV iron frame by a faulty electric hot water heater or other appliance  even though such a low enough resistance short should trip the breaker if all else is correct.

 I "preach" electrical safety on here time to time because that was a major part of my lifes career, even if some think in certain situations or NEC violations I've addressed in the past, the risk is so low or there's only a small chance of a problem they choose to ignore it   ITS YOUR LIFE AT RISK !!!!!!

 Sounds like some good advice above and you're already on the right track KEEP SAFE, CURE THAT HOT SKIN CONDITION.....

 PS a 50 amp tester which tests for BOTH hot 120 volt legs and Neutral at the source will be adequate UP TO THAT POINT although there can still be problems or reversals downstream in plugs or receptacles or adapters or panel etc !!!!   

 John T Longgggggggggg retired electrical power distribution design engineer and rusty so trust the NEC over me 

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9 hours ago, Big5er said:

For those times when you only have 30amp power at the pedestal, would this still work using a 30amp adapter? Or do you need TWO of these, one in 30amp and one in 50amp? 

Nothing stupid about that question at all. The answer is yes, as long as your 50a/30 adapter is properly wired. While mine was a Surge Guard product, I used it all of the time, even when using a 30a supply and now that we have downsized and travel in a 30a RV I use a 30a line protector and with 30a/50a adapter and they do work that way also. 

Quote

I currently have a cheap, plug in, meter that plugs into a wall outlet but I think finding out at the pedestal would be better.

2

I always use a line protection device but I also carry one of the outlet checking devices as well. After spending 40 years doing electrical repair work for a living, I prefer to be sure. The importance of the inside one is that while the line monitor protects you from issues caused outside of your RV, it does nothing for things which can happen inside. A ground connection coming loose in one outlet in a long string of them will take away the ground from all others. Using your small one will tell you if that happens and helps to trace the problem to its source. 

Edited by Kirk Wood
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Situation resolved without injury. 

And our winner is.... MrSeas - 

With honorable mentions to: J-T and John T Longggggggg - 

Confirmed the service outlet had reversed polarity and corrected. 

I had parked and plugged the trailer in to this 15 amp service to have lights and charge the batteries, test fans etc. I have been wearing rubber soled shoes and have a thick rubber mat on the ground at the entrance steps. 

I leaned a ladder on it's side up against the aluminum drop front of the trailer, while wearing rubber shoes and heard a "tick" as the ladder touched the bodywork and received a pretty good tingle shock to the hand... 

As Mr Longgggg said above - barefoot on the damp ground would not have been so minor.... 

Thanks for the help everyone. 

If someone with expertise wanted to post diagrams of the correct way to confirm polarity is correct at 15, 30, and 50 amp service plugs with a test meter - that might make a nice addition to the plug  devices shown above? 

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Congratulations, you callin me LONGGGGGGGGGGGGGGGGGGG lol I "resemble" that remark. As BOTH an Engineer and an Attorney its just in my DNA I cant help myself............................

Best wishes

PS this was already posted by a gentleman above, it shows polarity

http://www.myrv.us/electric/Pg/testing.htm

John T

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12 hours ago, noteven said:

If someone with expertise wanted to post diagrams of the correct way to confirm polarity is correct at 15, 30, and 50 amp service plugs with a test meter - that might make a nice addition to the plug  devices shown above? 

I don't know of an easy to use diagram but I do suggest this article from the No Shock Zone which explains things very well. 

20-30_Amp_120V-metered-300x223.jpg  50_Amp_240V-metered-300x226.jpg

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12 hours ago, oldjohnt said:

Congratulations, you callin me LONGGGGGGGGGGGGGGGGGGG lol I "resemble" that remark. As BOTH an Engineer and an Attorney its just in my DNA I cant help myself............................

Best wishes

PS this was already posted by a gentleman above, it shows polarity

http://www.myrv.us/electric/Pg/testing.htm

John T

No offence intended I was just fun in'  with how you wrote your name. 

Always enjoy your posts on "current affairs"

ok I'll quit now

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11 minutes ago, noteven said:

No offence intended I was just fun in'  with how you wrote your name. 

Always enjoy your posts on "current affairs"

None taken not even, I also enjoy teasing  and fun'in with all the fine gents on here. A great group of guys all willing to help and I try my best to do the same as often as I can.   Thanks for the kind words. That nickname "John T" was given to me yearssssssssssss ago and it just stuck 

Best wishes and God Bless

John T

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