Reduced voltage at particular receptacles

[mikaho]

My wife and I are new to full time RVing and recently bought a preowned Fleetwood Southwind 37U. We are working through identifying and corrected the inevitable maintenance issues. The day we picked it up I discovered that items plugged into one of three outlets in the entertainment cabinets right behind the passenger seat would not power on. It took a couple of weeks because issues with the water heater took first priority. So yesterday I started tackling tracking down that issue. I discovered two data points: The outlets in question are live but are only showing 80Vac. And they are on a seperate circuit from other outlets in the RV as I had previously determined which beaker the rest of the outlets are on and had that breaker off but still had voltage at the target outlets. I removed some interior panels in the cabinet to trace the wiring and located the incoming wire from the harness. I disconnected all outlets and measured the voltage across the hot and neutral wires directly and it is only 80Vac.

Any ideas would be much apreaciated!

[Kirk W]

Since this is a 2002 model, it is possible that a former owner has modified some of the wiring so some thoughts go to what is usually done at the factory and some go to what may have been done.

 

The fact that the circuit in question has only 80V with the other outlets at 120V tells me that it has to come from a different source. Bad connections can cause a voltage loss between outlets but that only happens when current if flowing and would not show any change when the circuit is open. You need to understand that voltage is the driving pressure of electricity while amperage is the measure of the amount of electricity, much like gallons/minute would be if we were to discuss water through a hose.

 

Since you can open the circuit breaker to your 120V outlets and the 80V is still there, this points me to look somewhere else. I would leave that circuit breaker open while you continue to trouble shoot. The next place that I would look is to see if you have an inverter which takes 12V-dc power from your batteries and supplies the outlets you are looking at. The outlets for the TV and VCR/DVR are by far the most common ones to be supplied by an inverter. Usually the inverter is designed such that it gets 120V into it also and will pass that to the TV receptical when available but will turn on and change 12V-dc into 120V-ac for those devices to allow you to watch TV when you do not have shore power. If you have an inverter, it is very likely the source of that 80V. Once we know for sure where that power is coming from, we can then address the reason for it being only 80V.

[mikaho]

Thanks, Kirk.

 

I did not think about the inverter as a power source but that seems like a likely culprit. now I just have to find where it is...

[Kirk W]

It is probably close to the batteries because it requires much larger cables on the 12V side. You may have a combination converter/inverter which does both jobs, supplying 12V when one shore power and 120V when without shore power. That is where I would look first.

[mikaho]

OK, some have some clarified information but still not sure why i'm not getting 110v.

 

I do not appear to have an inverter at all. At least I can't find it.

 

The CONverter is under the fridge and is not a combo converter/inverter.

 

I'm now know the outlets in question are running off the 120v breaker box. The breaker in question is protecting the outlets in the entertainment cabinet and the outlets in the cabinets above the dash board. All of those outlets are showing 100v tonight. When I put a meter on just the wire leads yesterday they read 80v. Those readings are with no loads running. I'm not sure how to put a load on the circuit since nothing I plug into the outlets powers up.

 

Any additional ideas would be appreciated.

[Kirk W]

I am wondering how you are measuring. Did you measure between the hot and neutral or hot to ground? You should measure not to neutral, but with the problem you have I suggest you measure between hot and ground also and then measure between the neutral and the ground. Take as accurate readings as you possibly can an let us know what you find.

 

If you have not done so, open the appropriate circuit breaker and then go back to the same point and do all three measurements again and record those. They should all be 0V, but................

 

Is your Southwind one with a 30A power cord or does it have 50A shore power? Are all of your measurements while on shore power? Are you taking the readings by sticking the probes into the slots of the outlets, or did you pull the outlets out of the box and measure to the screw connections? If you have not pulled it out to use the screws, do so now.

[mikaho]

Kirk,

 

My coach is 30A. I have been measuring between hot and neutral. I'll do the other measurements tonight.

[mikaho]

Just an update. Measuring between hot and ground returned 110v at all outlets on the chain thereby confirming the issue was a neutral wire connection somewhere in the chain. After killing all breakers except the one in question and working through all outlets in the coach, I found that there was one outlet in the bedroom apparently intended for a bedroom tv that was actually the first outlet in that circuit and that outlet read 110v across the board. After disconnecting and reconnecting that receptacle, I had 110v restored to the entire chain. The receptacles in this RV are obviously cheap and the connections are accomplished by pressing the wires into v slots and closing a back cover that ostensibly holds everything in place. For now everything works but I plan to replace all outlets with better ones featuring screw terminals in the near future.

 

Thanks for the help.

[Kirk W]

I think that you are now on the right track. The type of outlet that you have are some of poor design that I don't believe you even find today. My suggestion is that you should plan to spend about $2/3 each to get really good quality outlets. I only use the type that connect with screws and never buy the least costly ones. Better quality outlets have better electrical connections and they will last much longer without creating a poor connection to the blades of power plugs. You can save a little by getting them in boxes of 10 or so if you have that many.