Voltage in Travel Trailer

Don't fix something that is not broke. Your numbers, while certainly not ideal, are perfectly normal and safe for many campgrounds.

To find out where the problem is check the voltage at the pedestal under those varying loads. Most likely the drop is coming from that long run of wire to the main panel of the park that is undersized, and the voltage at the pedestal will be lower under load. Nothing you can do about that. If the voltage is stable at the pedestal then start to check your trailer and it's connection to the pedestal as that sounds like too much drop for the trailer itself.

Old-Biscuit wrote:
120V to 117V because a 12V DC furnace is running.............:H

Seems obvious to me - if the OP's battery isn't fully charged the converter, rather than idling in float mode will be in charge mode, creating it's own voltage drop on the incoming 120 vac source. Regardless, this is all speculation anyway as the OP hasn't provided sufficient detail indicating total load on the system, length of cable run, cable gauge, etc, so this is all a rather pointless discussion, not unlike saying "My truck is broken, what's wrong with it?" Good grief, who knows?!! :S

A lot of campgrounds are wired with wire that is inadequately sized. Voltage drop is normal with the amount being determined by the size of the feeder wires. Usually your TT cord is of the proper size. However, as others have said, poor/dirty plugs or receptacles can exacerbate the problem.

120V to 117V because a 12V DC furnace is running.............:H

I would be checking terminals/lugs for tightness on MAIN AC panel and on CONVERTER battery cable connections.

I would be checking converter DC Voltage output and battery state of charge.

DC Furnace draws 8A 12V DC........ 0.8A 120V

Don't know about your numbers, but voltage drop is perfectly normal with increasing loads.

Some drop is normal. You can tighten lugs on both leads in the panel, especially the neutrals. Check that leads on the plug are clean. A quick, ocassional wipe with a fine sandpaper works wonders.

Voltage drop may be normal. Whenever you have any concerns, check your cable connections for heating. If you have the twist-lock connection on the side of the trailer, heating there could lead to a disaster. My trailer had all loose wires in that connection. Whenever I plug in, I connect and disconnect at least three times, before turning on the breaker, to wipe the contacts.

I have one of these RV PLUG-IN AC VOLTMETERS that I can glance at and it tells me where the SAFE ZONE is when using the campground pedestal setup... The 120V LEVEL starting down at most campgrounds when more and more folks start showing up and plugging in...



If the 120VAC is on the bottom of the SAFE ZONE scale i will not use it for high wattage items...

Roy Ken

scrubjaysnest wrote:
This isn't likely to be normal.

Of course voltage drop is "normal" and the degree to which an unloaded nominal voltage source of 120 vac will drop once a load is placed on the circuit will vary depending on a number of a factors which include total load, cable length, cable gauge, and therefore cable resistance. One can easily estimate just what the voltage drop will be by plugging a series of numbers into a Voltage Drop Calculator. Trailers designed for 30 amp main service are wired with 10 gauge cable ... this screenshot illustrates voltage drop for a 30 amp load over 25' of 10 gauge main service cable so one could even extrapolate from this just what the drop would be for other values without even using the calculator. For example, if the load was just 15 amps over the same length of 10 gauge cable the voltage drop would also be half - i.e. 0.75 volts instead of 1.50 volts.