Electrical help needed

I have a 2003 Providence motorhome. There is a drop in voltage when I turn anything on. We use two electric heaters in the winter season and when we do the volts drop from 120 to 100. When I turn on the following the drops are,
Convection oven, 7 volts
Hair drier 3 volts
Electric heater 10 volts
Toaster 3 volts

Since we bought this unit we have had to;
Replace the circuit board in fridge twice
Replace two surround sound systems
Replace two direct TV receivers
Replace the thermostat for air conditioner three times
Replace switch for water heater which dealer says they don’t carry because they never go bad
We had a fire in junction box under bed
We had a fire in rear air conditioner

Can someone tell me how big a problem voltage loss is and what might be the cause is.

Electrical help needed

(Can someone tell me how big a problem voltage loss is and what might be the cause is.) The majority of the items that have gone bad have been a result of "LOW VOLTAGE". The main thing to remember is that voltage and current are inversive of each other. Voltage goes down -- current draw goes up.
Now you say you had a fire in junction box under bed fire and in rear air conditioner.
This indicates that you have some major electrical problems that need to be taken care of by a Qualified Electrician.

My best advice is for you to get a Qualified Electrician to go through the entire electrical system. Now when I say a QUALIFIED ELECTRICAN, I mean one that also knows and understands RV's.
Electrical help needed

Those voltage drops can be and are usually caused by insufficient shore power cord size or insufficient wire size leading up to the receptacle you are plugged into.

If you in an old park the circuit you are plugged into was probably installed long ago when electricity demands on the average RV were pretty minimal.

This is an EXTREMELY HAZARDOUS SITUATION. Get a licensed electrician to review the situation before you burn the RV up with you in it.

C Nash

Senior Member
Electrical help needed

Hi Mike and welcome to the forum. Have you checked the voltage drop with the generator running


New Member
Electrical help needed

I don't know if motorhomes come with a buck/boost transformer installed in them but I would surley get one if it doesn't have one; This maintains a constant voltage coming in.Also a loose connection on a hot wire could be the problem,but I would bet it is likley a loose connection on the netural or ground somewhere in the system..I don't know why all TT's,motorhomes.and etc. don't come with the above item,unless it's to hold down cost or sell as a option.You can get them from most camping centers..
Electrical help needed

You need to look at your amperage into the rig. If you have a 30 amp system running two electric heaters will almost use all of your incoming power. Electric heaters draw about 12 amps each. If you have any other 120 volt appliances on you have just about tapped out on your power.
With low amperage reaching your convertor you may not be getting a full 12 volts at any given time. This will cause damage to your printed circuit boards. If you have a 50 amp service (outside plug had 3 flats and a round) and a 50 amp box to plug into, you may want to check and see if you really have 50 amps to the box. Also if you are in a park and everyone is using electric heat you may have low voltage all over the park. I recomend using only one electric heater (oil filled seem to work the best) and get an amp meter to monitor your draw.
Electrical help needed

As mentioned above low voltage is dangerous to you and your equipment.
You didn't say if you were in a RV pak or at home but I'm assuming your in a park.
Get a volt meter and be careful. When you suspect a voltage drop, check at the power post where you plug in.
I once had a low voltage problem that turned out being dirty contacts on the coach's transfer switch.
In this case, voltage measured good until current draw was increased. With the high resistance of the dirty contacts the voltage dropped (which equated to loss) accross the contacts will rise as more current is drawn.
You'll want to check at the power pos at the same time.
Good luck.


Senior Member
Electrical help needed


First, I made my living working with electricity for more than 40 years so I do have some background knowledge.

What happens when that supply voltage to an electrical device falls depends upon what kind of load it is and if the power is AC or DC. In the case of DC it isn't serious as quickly, but if it falls far enough it will cause a problem. With AC power the load type makes a big difference. Only with inductive loads does the current increase when the voltage falls. That means things like AC motors and a few other items. But low voltage is never good. Appliances are designed for a particular voltage with a +/- range. For AC loads that range is +/- 10% or in other words, 12V. Anything outside of that will cause harm and what is worst depends upon the type of load. But, it is safe to say that the voltage should not drop significantly when a load is applied.

Just what the problem is must be determined by several measurements that you can take. The first question is, where are you measuring the decreased voltage? If it is at an outlet inside the RV, have you checked to see what the voltage is doing at the power pedestal outside? If the voltage is still the same at the pedestal, or close to the same, but significantly lower inside the RV, the problem is in the wiring of the RV.

Your statement that you had a fire in a junction box is an indication that there is a very serious problem with the RV's wiring. That probably means that there is something causing a heat build-up of some kind. Heat is normally caused by a high resistance, usually a bad connection. If the wire used in the RV is too small, that could also cause the problems.

Are you the original owner of this RV? If you are not, it may be that someone replaced the original circuit breakers with larger ones. That could also cause this problem. A voltage drop such as you have probably means that you have a dangerous wire problem in the RV. I suggest that you discontinue the use of any electric heaters until you know what the cause of this is. I would be most happy to assist you in trouble shooting this if you send me a request. But this is a very serious fire danger!


Senior Member
Electrical help needed

Another question? In my old Winnebago Chieftain, I keep a power gauge plugged into one of my outlets and monitor it when using the MH. It normally reads around 120 under normal use but will drop off about 5 to 8 volts (below the green area on the gauge) when I use the A/C or the microwave oven. Everything seems to work just fine, so is this a problem I ought to be looking at?????? :question:
Electrical help needed


Most everything 120 volts AC in your rig is good down to 105 volts AC without doing it any damage. Its been engineered that way. A drop of 5-8 volts with an older (1980-1995) air-conditioner on a 30 amp system is normal on start up. It should come back up a little after the compressor kicks in to just a few volts below normal. It may be more pronounced on start up when using your Gen-set just because it takes longer to catchup with the load.