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04-20-2012, 09:01 PM
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#1
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Rivet Master
2005 25' Safari
Salem
, Oregon
Join Date: Mar 2006
Posts: 8,369
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Polarity testers disagree.
Hi, today I pulled my trailer forward in my driveway to get a few things done. First thing that I wanted to do was try out my new Orange 30 Amp RV adapter. It seems to make sense that by plugging into the 20 Amp duplex receptacle on my generator and having one 30 Amp type RV receptacle would give the best contact for my shore power cord. [for all practical purposes, I know that I'm not getting 30 Amps] Next was to check for proper polarity. I have two polarity testers and I believe that one of them is wrong. The first one showed a red light and a center amber light; This indicates no ground and reverse polarity. The second polarity tester showed one center amber light; This indicates, no ground. I believe that the second tester is correct; What does your tester read when using a portable generator? And finally, when both of the testers are plugged into a house outlet, they both read correctly. What is your opinion of this?
__________________
Bob 2005 Safari 25-B
"Le Petit Chateau Argent" Small Silver Castle
2000 Navigator / 2014 F-150 Eco-Boost / Equal-i-zer / P-3
YAMAHA 2400 / AIR #12144
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04-20-2012, 10:27 PM
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#2
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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I had one of the yellow ones. It started reading goofy after about a year. I would get inconsistent readings in the trailer, which I know was incorrect. Checked the same circuits with another tester, everything was OK.
Took it in the house, since the wiring is only 12 years old. When I plugged it in to a standard outlet it read goofy again. Plugged it in to a GFI outlet and it tripped the breaker.
I threw it out and bought a replacement.
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04-21-2012, 12:09 AM
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#3
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Wise Elder
2010 30' Classic
Vintage Kin Owner
South of the river
, Minnesota
Join Date: Dec 2009
Posts: 4,169
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Bob
It is not unusual for the red light to glow at low intensity when there is an open ground or open neutral. Sometimes the amber lights will glow as well. Treat the lower intensity illumination as "off" for determining the situation. Some better quality testers don't do this but most of them do.
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04-21-2012, 02:11 AM
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#4
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Rivet Master
2005 19' Safari
GLENDALE
, AZ
Join Date: Aug 2004
Posts: 2,453
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System ground in Honda Generators
Not sure about the Yamaha, but in the owners manual for the Hondas there is a note about a ground fault error when using polarity testers. This is normal and safe condition (for Hondas). See quote from owners manual, below:
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GROUND SYSTEM
Connections for standby power to a building electrical system must be made by a qualified electrician. The connection must isolate the generator power from utility power, and must comply with all applicable laws and electrical codes.
Honda portable generators have a system ground that connects generator frame components to the ground terminals in the AC output receptacles. The system ground is not connected to the AC neutral wire. If the generator is tested by a receptacle tester, it will not show the same ground circuit condition as for a home receptacle.
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04-21-2012, 07:04 AM
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#5
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Rivet Master
1978 Argosy Minuet 6.0 Metre
Currently Looking...
Wauwatosa
, Wisconsin
Join Date: Oct 2010
Posts: 810
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I prefer to use a volt meter. Checking between all three slots in the receptical you should get a voltage reading two of the three combinations.For a 120v 15amp or 20amp outlet,
A correctly wired outlet:
Between the short (hot) slot and the long (neutral) slot should read voltage. Between the hot and ground (round hole) you should get the same voltage. Between the neutral and ground you should not get anything.
A non grounded outlet:
Between hot and neutral you should get voltage.
Between the hot and ground you should get nothing.
Between neutral and ground you should get nothing.
A reverse polarity outlet:
Between hot and neutral you should get voltage.
Between hot and ground nothing.
Between neutral and ground you should get voltage.
For a 120v 30amp outlet the hot and neutral prongs are on the same side as the 15 or 20amp. As your facing the outlet, with the ground on the bottom, the hot is to the right and the neutral is to the left.
__________________
Judging a person does not define who they are, it defines who YOU are.
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04-21-2012, 07:23 AM
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#6
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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I always use a meter when I have doubts about what the tester is telling me. I also check to make sure there is a good earth ground on the skin of the trailer. You can do that by checking between the hot side and the skin with a meter. You should read 120 VAC +/-
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04-21-2012, 07:27 AM
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#7
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Rivet Master
1981 31' Excella II
New Market
, Alabama
Join Date: Sep 2011
Posts: 6,145
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Did you try the plug in circuit tester directly in the wall instead of through the watt meter?
Perry
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04-21-2012, 08:50 AM
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#8
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Rivet Master
2006 25' Safari FB SE
Spokane
, Washington
Join Date: Sep 2009
Posts: 1,848
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Robert,
Phoenix answered your question. I can't speak about your two testers but both of them are telling you that the generator is not grounded.
Last year my cousin set up his dish on a tripod and ran the cable to the Airstream. It was raining outside and we were watching a ball game. My cousin was getting a static shock whenever he touched anything in the trailer. The strange thing was that I was not getting shocked. I checked the circuit and noticed the no ground. I got my VM meter and noticed a phantom charge of just a volt or two between the ground and the neutral slots in the coach outlets. I was convinced that something was amiss.
After reading the Honda manual, talking to the tech at the shop and reading on line I found that this is normal. Last week I met up with my cousin again and we did the same thing except this time the dish was mounted to this camper and was not touching the ground. No static shock anywhere.
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04-21-2012, 09:07 AM
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#9
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 20,000
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Quote:
Originally Posted by Phoenix
Not sure about the Yamaha, but in the owners manual for the Hondas there is a note about a ground fault error when using polarity testers. This is normal and safe condition (for Hondas). See quote from owners manual, below:
==========
GROUND SYSTEM
Connections for standby power to a building electrical system must be made by a qualified electrician. The connection must isolate the generator power from utility power, and must comply with all applicable laws and electrical codes.
Honda portable generators have a system ground that connects generator frame components to the ground terminals in the AC output receptacles. The system ground is not connected to the AC neutral wire. If the generator is tested by a receptacle tester, it will not show the same ground circuit condition as for a home receptacle.
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Bob
I got a spare 30a pigtail and re-wired gnd to neutral so the meters read correctly when on the genset.
Bob
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
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04-21-2012, 09:38 AM
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#10
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Rivet Master
1977 Argosy 24
Currently Looking...
Milltown
, Wisconsin
Join Date: Mar 2006
Posts: 1,087
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I had the ground and neutral on the same buss bar in my Avion. Every time I plugged into a ground fault breaker at a campground it would trip. I separated the ground and neutral in the breaker box in the Avion and now I can plug into a ground fault at a campground with no problem. The outlet tester read OK in the trailer wired both ways.
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04-21-2012, 09:51 AM
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#11
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Rivet Master
1975 29' Ambassador
Reno
, Nevada
Join Date: May 2003
Posts: 1,351
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Portable gensets under 5 kw with plugs are not required by code to have the chassis ground and neutral bonded together like they are for grid power. That confuses folks with the power checkers sometimes.
i.e. a power checker that shows only one light and an 'open' ground is OK for a plug in genset.
This is related to why your RV circuit box does not bond neutral and chassis ground together. The RV is a sub-panel and the bonding is not done because it would create multiple ground paths which is a safety hazard. Again, see the electrical code.
If you have a permanently installed genset with a transfer switch, that switch will usually take care of proper chassis ground bonding when doing its thing.
Sometimes folks will tie one of the power leads to chassis ground to 'fix' this problem. The lead they bond to chassis then becomes the neutral. That is really not necessary and may even be a bit of an increased safety risk.
That 5kw power level is about 'leakage'. With some testers, you may see a 'ghost' voltage between a hot lead and ground. This is because of induced current and is nothing to worry about until you get to very high power levels.
Notes: 'bond' means electrically connected together. Grounds come in many flavors so I try to use chassis ground to avoid confusion. Earth ground is an entirely different thing and has its own interesting issues. The modern (since the 60's or so) electrical plug ground lug is a chassis ground that connects to an earth ground at one and only one place in a grid powered facility unless very special precautions are taken. That place is also the only point where the power neutral is connected to the chassis ground in grid tied systems.
re: " It was raining outside and we were watching a ball game. My cousin was getting a static shock whenever he touched anything in the trailer." -- watch out and be careful about jumping to conclusions! A static shock is an entirely different thing than the shock you can get from improper wiring. It is one of the things that chassis grounding covers but not neutral to chassis ground bonding. Static shocks can be just due to shoe sole and walking surface differences or it can be because the chassis ground is not connected between the antenna and the rig. Be careful messing with the power leads connections to things unless you really really know what you are doing.
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04-21-2012, 09:52 AM
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#12
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Rivet Master
1973 23' Safari
1977 23' Safari
2018 25' Flying Cloud
Palmer Lake
, Colorado
Join Date: Oct 2005
Posts: 4,092
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Quote:
Originally Posted by ventport
I had the ground and neutral on the same buss bar in my Avion. Every time I plugged into a ground fault breaker at a campground it would trip. I separated the ground and neutral in the breaker box in the Avion and now I can plug into a ground fault at a campground with no problem. The outlet tester read OK in the trailer wired both ways.
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You have to have the ground and neutral tied together on the hot side (upstream side) of the GFI for it work correctly. When you plug into shore power [at your house, for example] your camper looks like an extension of any other house circuits. If the neutral and ground is tied together downstream, then the GFI sees current in both of them and trips. You only want current in the neutral leg.
But since a genset it the upstream (hot) end of the circuit, why don't they tie the frame ground to neutral. Is it so that a generator can be tied into a breaker box and not duplicate the neutral-to-ground tie?
Zep
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04-21-2012, 11:05 AM
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#13
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Rivet Master
1977 Argosy 24
Currently Looking...
Milltown
, Wisconsin
Join Date: Mar 2006
Posts: 1,087
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Quote:
Originally Posted by Zeppelinium
You have to have the ground and neutral tied together on the hot side (upstream side) of the GFI for it work correctly. When you plug into shore power [at your house, for example] your camper looks like an extension of any other house circuits. If the neutral and ground is tied together downstream, then the GFI sees current in both of them and trips. You only want current in the neutral leg.
But since a genset it the upstream (hot) end of the circuit, why don't they tie the frame ground to neutral. Is it so that a generator can be tied into a breaker box and not duplicate the neutral-to-ground tie?
Zep
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Now that finally makes sense to me thanks, Brian.
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04-21-2012, 11:26 AM
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#14
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Ready-to-Travel
2012 30' International
Walkerton
, Virginia
Join Date: Dec 2003
Posts: 3,166
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What do you think of running a ground wire to earth from the generator grounding screw? Is the absence of that ever an issue?
Pat
__________________
--------------------------------------
Somebody, please, point me to the road.
AIR 3987
TAC VA-2
WBCCI 4596
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04-21-2012, 11:50 AM
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#15
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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Most he sets sit on vibration isolation pads, usually some kind of rubber or plastic. Unless you drive a ground rod or have another means of actually tying it to earth ground, it seems like it really doesn't have a ground.
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04-21-2012, 12:40 PM
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#16
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Rivet Master
1973 23' Safari
1977 23' Safari
2018 25' Flying Cloud
Palmer Lake
, Colorado
Join Date: Oct 2005
Posts: 4,092
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Quote:
Originally Posted by pmclemore
What do you think of running a ground wire to earth from the generator grounding screw? Is the absence of that ever an issue?
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Pat, if it was you'd think the generator people would put that in their manuals. There is one time when you can get bitten--it's when your power cord is wired backwards and you have one of those reverse polarity lights on the Airstream. That bulb will put hot onto the shell and if the generator ground is not tied to earth, then the shell will zap you when you step off the step onto wet ground.
Take the idiot bulb out! Now the only way to get hot onto the shell is if the ground wire is wired to hot, which usually doesn't happen. The mistake people make is to reverse the hot and neutral.
Zep
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04-21-2012, 01:21 PM
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#17
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Rivet Master
1981 31' Excella II
New Market
, Alabama
Join Date: Sep 2011
Posts: 6,145
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It is not a bad idea to ground the trailer and generator with a grounding stake. This way if you end up with the hot touching the skin of the trailer it will trip a breaker instead of curling your hair. When you are hooked up to ground power you are grounded through the pig tail. In most states, trailers that are permanantly installed have to have a grounding stake. Trailers need to be well grounded so that if you get a lightening strike it will travel through the skin to ground.
Perry
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04-21-2012, 01:29 PM
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#18
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"Cloudsplitter"
2003 25' Classic
Houstatlantavegas
, Malebolgia
Join Date: Jun 2007
Posts: 20,000
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Quote:
Originally Posted by pmclemore
What do you think of running a ground wire to earth from the generator grounding screw? Is the absence of that ever an issue?
Pat
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Pat,
I do just that, you can see the two copper straps, washer and spike in the photo.
Don't know if it does much as the spike is only 12" long, but it makes me feel better and the terminal's there, might as well use it.
Bob
__________________
I’m done with ‘adulting’…Let’s go find Bigfoot.
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04-21-2012, 03:11 PM
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#19
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Master of Universe
2008 25' Safari FB SE
Grand Junction
, Colorado
Join Date: Sep 2007
Posts: 12,702
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I used to know how far to drive a copper rod into the ground for a house, but have not been able to access that memory. So I will guess 4 or 5'. The wetter the ground, the better the ground. Bring a rod, a really big hammer and something to pull it out.
I used to know this because I noticed after we bought this house there was a grounding cable to the copper pipe in the basement. This is often used to ground the electrical system since the pipes are buried in the ground before they enter the house. There was one problem—the water came into the house in PVC. The service entrance was grounded to a small rod outside, and I suppose that was good enough, but I bought a bigger, longer rod and tied it to the wire coming from the service entrance and pounded the rod in about 6'. I also put it farther from the house where the ground would be more damp.
Bob, why not check the polarity and ground with a multimeter or voltage meter to see which of your test lights is telling the truth?
Gene
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04-21-2012, 04:40 PM
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#20
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Rivet Master
1974 Argosy 26
Morrill
, Nebraska
Join Date: Nov 2009
Posts: 6,014
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Ground rods are 8' long. It would take an awful lot to pull one out that has been buried for any time.
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