Buzzing Noise from Transfer Box

[porchdog2]

There is a humming/ buzzing sound coming from the transfer switch.The unit is prepped for a generator, but one is not installed.It has been making this noise for at least a couple of months.I have pulled the cover on the switch box and everything "looks" ok. The box is not hot to the touch and no smells like wiring is getting too hot.This is on a winnebago 5th wheel using 50 amp service.Everything electrical works fine on the trailer.The sound can't be heard inside the unit, only when accessing the basement area.
I thought I would run this by the folks on here before calling the dealer tomorrow.

[Spk64]

With power removed I would check all the wire connections. They can work loose and humming will increase.
I had a loose neutral and the humming was much better after tightening.
Also depending on which type of coils (AC vs DC) are in the relays will impact the amount of noise.


Steve

[Old Scout]

Lots of info on this subject on the forum--basically, its a design issue. For most x-fer boxes, the default is genset, even if one is not installed, so the box has to switch to shorepower when plugged in. Many boxes are also designed to use AC current to actuate the contactors, vs DC current--thus more hum from the "alternating" current. Finally, as these boxes wear--they tend to hum more.
PS--good maintenance item is to, on a routine basis, loosen and retighten the lugs inside the box [with the power off, of course]

[Happy Prospector]

It could be stating to fail because of bad coils, now might be a good time to buy a replacement to have on hand.

How is your fire insurance? Electrical problems don't have a history of getting better with age.

You know the old saying: Pay me now, or pay me more latter.

[porchdog2]

Originally Posted by Spk64

With power removed I would check all the wire connections. They can work loose and humming will increase.
I had a loose neutral and the humming was much better after tightening.
Also depending on which type of coils (AC vs DC) are in the relays will impact the amount of noise.


Steve

I will disconnect from power tomorrow and check connections. This trailer is less than a year old and I suspect the connectors worked loose, or were not tight to begin with.

Thanks

[MikeAndPeggy]

Originally Posted by porchdog2

I will disconnect from power tomorrow and check connections. This trailer is less than a year old and I suspect the connectors worked loose, or were not tight to begin with.

Thanks

This has been a problem that occurs in most RVs that have one of the less expensive AC transfer switches. I've had a few of them and have even had some replaced but to no avail. For some (stupid) reason, the transfer switches I've had were all installed either directly under the bed, or in the basement under the bed. The DW had problems sleeping because of the noise.

I finally took matters into my own hands and, since I didn't have a generator installed, I bypassed the transfer switch. For those who do not have a generator installed - you may want to do the same is I did. After disconnecting power from the RV, I opened up the transfer switch, loosened all the screws holding the input cable and the output cable and with wingnuts (wire connectors), joined the input wires to the output wires. One of my RVs had 30 amp service and so there were only 3 input and 3 output wires to join together. For the 50amp RV, there were 4 wires. On my RVs the input wires and output wires were all colored the same - red to red, black to black, etc. I filled the wingnuts with silicone to insure no moisture would invade the connections and secured the wires so they wouldn't just hang loose. No more sound and the DW now sleeps more soundly.

[twinboat]

Are you sure it's the transfer switch and not the converter ?

Many are built in the same enclosure.

Just throwing it out there.

[MikeAndPeggy]

Originally Posted by twinboat

Are you sure it's the transfer switch and not the converter ?

Many are built in the same enclosure.

Just throwing it out there.

I'm positive. We're on our 10th RV now and I've done minor and major work on all of them. Only one of our RVs had a humming converter - fortunately it hummed only slightly and only when some of the 12v lights were on. The lights were turned off at bedtime so no humming at night.

[porchdog2]

Originally Posted by twinboat

Are you sure it's the transfer switch and not the converter ?

Many are built in the same enclosure.

Just throwing it out there.

Yes........transfer switch.

[porchdog2]

checked all lugs, nothing loose. The currant draw vibration seems to be the main deal,when I fiddle with the cover to the TS box the hum will change.It is not something i cant live with, just wanted to know what was causing it.I fret alot