| new plug ground-nuetral [message #95172] |
Mon, 09 August 2010 21:18  |
pzerkel
Messages: 212
Registered: September 2007
Location: Salisbury, IL
Karma: 0
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Senior Member |
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I just put a new plug on the coach (old one was missing ground pin) and tested the resistance between ground and neutral pins. I was getting about 40 megaohms resistance. That is a lot, but is not infinite.
So do I have a problem I need to find, or is the 40 megaohms close enough to infinite?
Test was done with all coach breakers Off.
Paul Zerkel
'78 Eleganza II
Salisbury IL (near Springfield)
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| Re: new plug ground-nuetral [message #95179 is a reply to message #95172] |
Mon, 09 August 2010 22:21  |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| pzerkel wrote on Mon, 09 August 2010 22:18 |
I just put a new plug on the coach (old one was missing ground pin) and tested the resistance between ground and neutral pins. I was getting about 40 megaohms resistance. That is a lot, but is not infinite.
So do I have a problem I need to find, or is the 40 megaohms close enough to infinite?
Test was done with all coach breakers Off.
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Paul,
I would wonder what you tested that with and how.
If you used any normal meter and you got fingers in there, this is about what you will get.
Meg-ohm meters use 500 or 1KvDC so that they can effectively read in the 1000Megohm+ range. At even 500V, you use the clips and don't touch anything.
If 40meg is what you have got, it will probably do. An inspector will want at least 100 before he sign off. But, at 120V, that will not be too bad.
Even with the breakers open, the status of the ground and neutral do not change.
If you want to trouble shot this, you will have to start digging around in the panel. Damp dust on the insulation block for the neutral buss can get you that low or lower pretty fast.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: new plug ground-nuetral [message #95182 is a reply to message #95172] |
Mon, 09 August 2010 22:33 |
pzerkel
Messages: 212
Registered: September 2007
Location: Salisbury, IL
Karma: 0
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Matt,
Thanks. I tested with Fluke 179 DMM. tThe test leads were just probes (not alligator clips) held to the plug pins.
I have a GM finished coach so plug is a NEMA 14-50.
As far as damp dust, at 90% relative humidity, pretty much anything I look at here right now is "damp".
I will take a closer look in the panel tomorrow evening.
Paul Zerkel
'78 Eleganza II
Salisbury IL (near Springfield)
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| Re: new plug ground-nuetral [message #95195 is a reply to message #95172] |
Tue, 10 August 2010 05:43 |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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NO, you do not have a problem. Recent article in the FMCA magazine states and quotes the NEC (national electricle code). The nuetral and the ground are NOT bonded in the panel of your GMC. Only in the panel feeding the plug your GMC plugs into.,,,,,,,,, Paul{electrician for 32yrs}Leavitt
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| Re: new plug ground-nuetral [message #95203 is a reply to message #95195] |
Tue, 10 August 2010 07:41 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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| g.winger wrote on Tue, 10 August 2010 06:43 |
NO, you do not have a problem. Recent article in the FMCA magazine states and quotes the NEC (national electrical code). The neutral and the ground are NOT bonded in the panel of your GMC. Only in the panel feeding the plug your GMC plugs into.,,,,,,,,, Paul{electrician for 32yrs}Leavitt
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Paul,
You are correct, but this Paul is asking the question from the other side. He is seeing some grounding of the neutral (admittedly 40meg), and was concerned that it was too much.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: new plug ground-nuetral [message #95218 is a reply to message #95203] |
Tue, 10 August 2010 11:42 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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Senior Member |
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| mcolie wrote on Tue, 10 August 2010 05:41 |
He is seeing some grounding of the neutral (admittedly 40meg), and was concerned that it was too much.
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Or too little... depending on your point of view.
He was looking for higher resistance and lower conductivity between ground and neutral.
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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