120 Volt outlet ground/hot reversed?

[kennethjhouse]

We are having a problem when our 2008 13B when it is at home and attached to shore power by an extension cord. Sometimes there is no 120 v power to the outlets. I plug in a circuit tester in the outlet and it shows the ground/hot leads are reversed when this occurs. When I put a voltage tester in the plug slots there is no reading. When I put one lead in a slot and one in ground hole, I get 120 V, so it probably is truly reversed. I have checked the house outlets and the extension cord. They are supplying 120 V correctly. Something is happening either with the converter we have to attach the extension cord to the 30 Amp original equipment black power line or within the trailer wiring itself. Sometimes when I unplug and plug the extension cord back in, the problem is fixed, but it sometimes reoccurs without changing anything. I notice this has not happened in a campground. So I am suspecting the converter since we hook the 30A line directly to the campground outlet. The converter came with the trailer when we bought it used. It looks good, but might be shorting. I need to check the power coming out of the converter it occurs to me as I write this. Duh!
Any suggestions are welcome. My next move is to buy a new converter and hope the problem goes away.
Thanks so much!!

[Centex]

Just curious, does your 2008 have the "EMS" (Electrical Management System) option? That would be in the path between the 30A cord and the Power Center / AC distribution panel.

(No, I don't know if it was even offered in 2008?)

I'm having trouble imagining what the "converter" per se (the component in the Power Center that converts AC to DC) has do do with the AC distribution in the trailer?

Wiring in the AC distribution side of the Power Center (including neutral and ground bus/terminal bars), now that's another matter perhaps?

[Ron in BC]

Originally Posted by kennethjhouse

When I put a voltage tester in the plug slots there is no reading. When I put one lead in a slot and one in ground hole, I get 120 V, so it probably is truly reversed.

You don't need a new converter.

You have a basic wiring problem. When you don't get power between the two flat blades that means the ground is probably not connected. When you get power from using one of the blade sockets and the ground pin that confirms that you don't have a functioning ground or neutral wire.

Check you extension cord again. It's a very basic main panel. Check voltage between the black and white wires, it should be 110 without using the ground terminal.

Ron

[sameo416]

Does the circuit tester indicate if you have a live ground? Some do and some don’t.

If you have hot and neutral reversed a multimeter should still show voltage slot to slot. Narrow slot to ground should show 120 V, so that's not proof of a reversal.

The EMS is a system that can take power on and off. What you're describing sounds like you may have an intermittent neutral or hot connection. I would step through the system from power connector to internal outlets to check voltage at each point NH NG HG. Output of the convertor important too.

[davescape]

About 95% of the time electrical problems are caused by faulty extension cords or other flexible wiring. Unless the cord has been cut, the problem is also most likely within 6" of end of the cord. Flexing the cord at this point will typically induce an on/off experience. Also check the male ends of the plugs, if they are black it indicates arcing. This arcing will damage both the male end of the plug as well as anything that it has been plugged into (ie. the female end). A proper repair replaces both connection points otherwise the damage will be repeated.

[padlin]

Kenneth, what are you considering a "converter"?

[Jim Bennett]

Originally Posted by padlin

Kenneth, what are you considering a "converter"?

I think he is referring ering to the 15A to 30A adapter.

While most plug testers do show a fault and usually what that fault is, I like to check with a multimeter if a problem is shown.

With leads connected properly to the multimeter, red to hot (small slot) and black to neutral (large slot) or ground should give you a positive 120V. Anything else shows a fault.

Neutral to ground should show no voltage, but should show continuity when reading the resistance.

I personally like to check the house outlet first, and if it is fine then the female end of the extension cord plugged in next. Both should give correct readings, but if the house is correct and the cord not it shows a fault with the cord, something as noted that is not uncommon, especially with cheaper cords.

While not entirely impossible, I too would bet the adapter is just fine.

[padlin]

Originally Posted by Jim Bennett

I think he is revering to the 15A to 30A adapter.

While not entirely impossible, I too would bet the adapter is just fine.

That's what I was thinking.

[sameo416]

Originally Posted by sameo416

Does the circuit tester indicate if you have a live ground? Some do and some don’t.

If you have hot and neutral reversed a multimeter should still show voltage slot to slot. Narrow slot to ground should show 120 V, so that's not proof of a reversal.

The EMS is a system that can take power on and off. What you're describing sounds like you may have an intermittent neutral or hot connection. I would step through the system from power connector to internal outlets to check voltage at each point NH NG HG. Output of the convertor important too.

If you're still having problems I would ditch the outlet tester and use a multimeter to check voltage at each step between the outlet in the house you're using to an outlet in the trailer. Anywhere you can access the connection until you isolate the issue. Don’t assume the house outlet is good, test at each connection.

What you should see is this when plugged into the house outlet:
HN (short slot to long slot) 110/120 V hot-neutral
HG (short slot to pin) 110/120 V hot-ground
NG (long slot to pin) 0 V neutral-ground

If HN is not 110/120, you have a hot or neutral broken
If HG is not 110/120 you have a hot or ground broken
If NG is not 0, you likely have a H-N reversed

If HG is 110/120 but HN is 0, broken neutral
If HN is 110/120 but HG is 0, broken ground

You likely don’t have a HN short or a HG short as either should trip the house breaker quickly.

If its intermittent I would start by swapping out the extension cord. If not the extension it could be a 2 person job, one to watch the meter and the other to shake wires to look for an intermittent connection.

This is a reasonable resource:

What Does a Hot Ground Reverse Receptacle Test Reading Mean? https://www.doityourself.com/stry/wh...e-reading-mean

[Ron in BC]

Many of us have basically said the same thing but you've said and laid it out in a nice easy to understand manner.

I've no doubt at all it's a pretty simple problem and step-by-step trouble shooting will pinpoint the problem.

A couple of weeks ago I had to track down why my trailer power wasn't on. Turned out to be the extension cord hot wire was loose on the terminal and making intermittent contact. But these things happen.

Ron