Lost the neutral in my travel trailer..... i think

I have a 2007 Fleetwood Mallard 28ft. When I plugged in the power this weekend, there was a loud quick buzzing noise and then it stopped. The a/c would come on for about a second and stop. I tried you use the microwave but the interior light got REAL bright and it stopped working. We also test plugged a box fan up and it like to have took off from going so fast lol.  Anyone experienced this?

If the Mallard has 50A shore power and was plugged to a 50A outlet, loss of neutral could do that. Not for a 30A RV, though, or even a 50A RV plugged to a 30A outlet.

If its a 30A RV, or plugged to a 30A outlet, it could be that the outlet is actually 220/240vv rather than 120. That shouldn't happen at an RV park, but maybe in some other place? A 220v, 3-prong outlet as used for some equipment (e.g. a welder ) is unfortunately identical to an RV 30A/120v outlet.

First step is to determine if the problem is in the RV or the outlet. Can you try it on a different outlet (preferably on a different power pedestal) and see what works and what does not?  Even if the other outlet is only 15/20A?

I have used it a few times with a 15amp adapter plugged into my generator with no issues.  I tried hooking it to an outdoor heavy duty extension cord and it melted the adapter

Gary RV_Wizard said:

If the Mallard has 50A shore power and was plugged to a 50A outlet, loss of neutral could do that. Not for a 30A RV, though, or even a 50A RV plugged to a 30A outlet.

If its a 30A RV, or plugged to a 30A outlet, it could be that the outlet is actually 220/240vv rather than 120. That shouldn't happen at an RV park, but maybe in some other place? A 220v, 3-prong outlet as used for some equipment (e.g. a welder ) is unfortunately identical to an RV 30A/120v outlet.

First step is to determine if the problem is in the RV or the outlet. Can you try it on a different outlet (preferably on a different power pedestal) and see what works and what does not?  Even if the other outlet is only 15/20A?

Click to expand...

The 30 amp outlet may well come off 1/2 of a transformer that provides 220 volts.  If the neutral line is open or has a bad connection, the neutral reference will "float" and, depending upon the earth ground configuration, cause the voltage to go very high, as much as 220 volts, even.

ac doing the same thing when I plugged up to 115 20A at the house. Extension cord getting hot too. No power to lights with battery unhooked either

I realize this is closing the barn door after the horse ran off, but install a Progressive EMS.  When you plug into it, the Progressive will tell you if the power is ok or what the problem is.  It will fix nothing in the camper that is already toast, but it will prevent it from happening again.  May help troubleshoot the problem now, if it is a supply issue that persists.

I think that you plugged into a 220v outlet.


You shouldn't have power to the lights when the battery is disconnected.

The 30 amp outlet may well come off 1/2 of a transformer that provides 220 volts.  If the neutral line is open or has a bad connection, the neutral reference will "float" and, depending upon the earth ground configuration, cause the voltage to go very high, as much as 220 volts, even.

Click to expand...

Nearly all 30A/120v outlets are fed from a 240v split phase or a 230v three phase source, so yes the outlet can have improper voltage if its neutral source is bad. Nothing can be done about that in the RV, though, except to move to a different and properly powered outlet.

ac doing the same thing when I plugged up to 115 20A at the house. Extension cord getting hot too. No power to lights with battery unhooked either

Click to expand...

martind's subsequent message pretty much isolates the problem to the RV. Voltage measurements are the first thing needed. At the outlet, at the load center in the RV, at the a/c, at the converter input & output, etc.

Gary RV_Wizard said:

Nearly all 30A/120v outlets are fed from a 240v split phase or a 230v three phase source, so yes the outlet can have improper voltage if its neutral source is bad. Nothing can be done about that in the RV, though, except to move to a different and properly powered outlet.
martind's subsequent message pretty much isolates the problem to the RV. Voltage measurements are the first thing needed. At the outlet, at the load center in the RV, at the a/c, at the converter input & output, etc.

Click to expand...

You will probably never see a 230 volt three phase system, which is known as a Three Phase, Four Wire Delta.  I suspect what you are referring to is a Three Phase, Four Wire Wye system, which is quite common, although I would be very surprised to see one in a modern day RV setting, as the phase to phase voltage is 208 volts.  They are more commonly found in commercial applications where they are used to supply 120 volts (phase to neutral) for receptacles and lighting.  Each phase...A, B, and C when paired with the neutral wire provides  a 120 VAC circuit.  It can also be used to provide three phase power to smaller three phase motors

The single phase or split phase is by far, the most common setup and this of course is what is found in all of your residential settings

Thank you all VERY MUCH for your thoughts . Im going to work on it this weekend and check the voltage reading and will check back with the group. Yesterday it was plugged in to the neighbors power and has the same results.

although I would be very surprised to see one in a modern day RV setting, as the phase to phase voltage is 208 volts.  They are more commonly found in commercial applications where they are used to supply 120 volts (phase to neutral) for receptacles and lighting.

Click to expand...

True enough, but RV parks, or at least RV hook-ups, are sometimes associated with "commercial applications" of all sorts. Both 230v and 208v may be encountered from time to time. I worked two summers in one park that was all 3-phase because it was part of a water theme park that ran numerous industrial grade pumps on 3-phase. Have also encountered it at RV repair facilities.

This is well off-topic and not helping MartinD at all, so let's focus on his issue.

I'm a retired power company electrician, so I feel your pain.....a missing neutral can definitely cause what you are seeing.  A missing neutral will cause one side of the service to go high and the other side to go low, depending on load.  I hate to smile, but you saying you kept "testing" things by turning them on and (waiting for smoke) is really funny.  Nothing that I'm aware of on an RV uses 240V so everything uses 120V line to neutral.  Definitely DO NOT turn anything else on until you find the problem.  A meter is really the only sure way to test a power source.  The comments about 3 phase, 120/240 vs. 120/208 is interesting but not likely your problem (240 4W Delta will show 208 on the "high" leg to neutral) so reading any 208 may not help you know what you have.  If you're not comfortable working with "hot" wiring, get some help.  These kinds of problems can become VERY expensive in a hurry.  Let us know what you find.  You said you plugged into your neighbor's power with the same result.  Was it just a regular 120V extension cord or was it a 240/120 source?  If you use a standard 120V cord and you have a neutral problem, only half of the things in your RV will work or nothing will work.  The ones with a missing neutral won't.  No smoke.  Definitely sounds like a wiring problem in your RV.

MartinD has not yet confirmed whether his RV has a 30A/120v power system (3 pront plug) or a 50A/240v system (4-prong plug). If he has a 30A system, then he cannot have a floating neutral within his RV unless the external source itself is bad (floating). A bad neutral in a 30A system is simple - there is no power. On a 50A system, more possibilities exist.