Since I know only enough about electricity to get the you-know-what shocked out of me, I thought I'd ask the experts. Today, while exercising the generator, I was bored and got out my circuit tester. It's that yellow one with the four lights on the end.
Well, much to my surprise, it indicated reverse polarity on every outlet in the motorhome.
The odd thing was that the two electric heaters that I plugged into those outlets worked fine.
Bad tester? Or am I missing someting...because I thought reverse polarity would pretty much destroy those electric heaters!
Although many things work fine with reversed polarity, I wouldn't agree that it "doesn't make a hoot of difference." If the polarity is reversed, a fault between hot (now the neutral or white wire) & ground will not trip a breaker since the breaker is not protecting the neutral. Another problem - a few electronic devices built during the 50's & 60's had the chassis tied to the neutral. Although the manufacturers went to a great deal of trouble to insulate the chassis from the outside world, consumers did a good job of defeating the insulation. End results - shocks to ground from the knobs & switches of appliances. Probably not too much of a problem now since most of those devices have come & gone, but of some concern. One last point - modern devices are often designed so that the parts that a consumer is most likely to touch are connected to the neutral (grounded) side. Example - a lamp socket. The shell is connected to the neutral & the button at the bottom is the hot. Reversing the polarity makes the shell hot to ground, increasing the chance of a shock if the consumer replaces a lamp with the device plugged in.
By the way, the older receptacles had narrow, not wide blades. The wide blade is the grounded conductor or neutral.
As to the circuit tester indicating a problem - it only works properly with systems that have the neutral tied to ground (usually at the service entrance). If an RV generator only produces 120V, there is no requirement that the neutral be connected to ground. Some manufacturers do tie the white wire to ground, others don't. If it is tied to ground, it must be untied when connected to shore power since the only place it is legal to tie the identified conductor or neutral to ground is at the campground's service entrance.
My honda does not have polarity, it is a floating voltage. AC coming from the power company has the netural at ground potential. I have never checked the Inverter. The generator has a warning label the Inverter does not.
I tested electrical systems in homes for 10 years with one of those circuit testers. If you were running off your generator and not off shore power this is your problem. It is not a reversed polarity. It is an open ground. Is your generator grounded? Is it built into your coach? If so, then the tires are preventing you from grounding. Take a wire, tie it to your grounding lug on the generator, stick the other end into the ground outside. It should read correctly. Hook to shore power to make sure your coach wiring is correct.Those testers lie when you have an "open" ground.
To the other poster about reverse polarity... yes it does make a huge difference. If it is reversed, you are essentially running power through you neutral circuit... this is backwards. If the panel is bonded (neutral and ground tied together) in the converter, you are essentially running current through the frame of the rig. This can cause a serious electrocution hazard.
04 Lariat Supercrew 4x4,5.4,3.73, Edge tuner, flowmaster duals
06 Trail Bay 31BH, nicely optioned
Equal-i-zer
Prodigy
Follow vehicle, 05 KIA Sorento EX for the golden retrievers.
Normal house wires have 3 wires.. HOT, Neutral and Ground
Now, there is a reason you need a ground.. I will try to explain it
Power comes into the house, there is a safety ground at the service entrance, There is also a ground "elsewhere" on the secondary side (Primary is the high tension wires, secondary is the drops to your house, and the neighbor's and the.. Well you get it.)
Now let's assume that something happened. You are using, oh, say an electric drill, and there is a hot-wire to case short..IF you have not tampered with the round pin on the plug, then the case is connected to ground, the fuse (or breaker) goes and ... Well, it may take you a while but you figure it out, toss the drill and buy a new one that works.
Now let's run that same drill WITHOUT the safety ground
now we get the hot-to-case short... There being no other path to ground... It grounds via you... Been nice knowing you. Pardon if I'm not at your funeral but my travel funds are limited just now.
Hence the safety ground.. The "Three Light Tester" has a light from HOT to Neutral, From HOT to Ground and from Neutral to Ground. Proper the H-N and H-G lights light
When you run on the Generator though things are different (normally) there is no safety ground. So in the case of the shorted drill mentioned above.. THE CURRENT CAN NOT RETURN THROUGH YOUR BODY as there is no ground path back to the generator. (Unless. of course they bond neutral to ground) thus. The "REVERSE" light will come on... So should the "Proper" light, You should see all three lights on a generator
Nothin adds excitment like something that is none of your business
Kenwood TS-2000 housed in a 2005 Damon Intruder 377
I believe that lack of green ground is why the Honda inverter generators built for the CA market can't be paralleled. Apparently US codes allow it for small generators but CA codes don't.
So on shore power using the three light tester, I get "correct" two yellow lights on the shore power outlet and at all outlets in the trailer.
Eliminator 400w inverter clamped to the battery lugs I get all three lights at the inverter AC outlets, which is not a choice on the tester's diagram, so it must be impossible
Honda 3000 says it has a floating neutral. The tester shows only one yellow light in the middle indicating an "open ground". When shore power cable is plugged into the gen, all trailer outlets also indicate this same condition of Open Ground.
There is a grounding method for the Honda using its frame but I don't bother with that. I work it from the bed of the truck (on tires) to the trailer (on tires) and so far we are still alive.
IMO if the OP has a red light indicating reverse polarity in his rig's outlets this is bad news, and the problem should be corrected.
(1)Does the outlet tester read correctly when plugged into shore power? and (2) Is this a built-in or portable generator.
If the reading is ok on shore power and it's a built-in generator, I believe the only answer is that the generator is wired incorrectly to the RV. The electrical devices usually don't care at all if the polarity is reversed. It's a personal safety issue.
Wayne Dohnal wrote: It would be helpful to know two more things:
(1)Does the outlet tester read correctly when plugged into shore power? and (2) Is this a built-in or portable generator.
If the reading is ok on shore power and it's a built-in generator, I believe the only answer is that the generator is wired incorrectly to the RV. The electrical devices usually don't care at all if the polarity is reversed. It's a personal safety issue.
Offline
 (133 x 100).jpg)
