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Lit · 11-09-2012, 09:10 PM

I have an electrical hum coming from my 50 amp Power System Transfer Box while I’m connected to shore power. Does anyone have any idea of what causes this, and how do I silence it?

Skip426 · 11-09-2012, 09:18 PM

Living with the same issue, I'm tagging along to see what answers you get .

Hopefully not $$$$$$

Dan DeBruin · 11-10-2012, 04:27 AM

I had the same hum in my old coach. Never got rid of it until I traded in the motor home and got a different one. Not sure if it was the kind of transfer switch but the new coach is silent, both in switching from house to shore power and while connected. Sorry, don't know the answer to your question either, I actually got to trust the hum to know it was connected. Since I store it in my back yard, a couple of times I realized there was a shore power issue by walking by the coach and not hearing the hum

had blown the GFI's and shut down shore power.

GRIFF53 · 11-10-2012, 07:40 AM

We had the same Humm coming from the electric box area in the bedroom while plugged into shore line. Took the motorhome in and had to have the transfer switch replaced. The part had to be ordered so we had to leave the coach a few days. The part was about $700 but we had a warranty to cover it so only cost us $100 deductible. It fixed it because now there is no noise when we plug in. We never heard the noise when running off the generator so we figured it was something to do with the transfer to electricity.

Oscar Mike · 11-10-2012, 07:52 AM

I have the exact same issue with my Fleetwood Bounder. I am taking it in to the dealer on Monday for them to finish the PDI corrections, I just added the transfer switch to my list.

Qwert66 · 11-10-2012, 08:16 AM

Generally speaking 50 amp transfer switches contain 2 heavy duty relays and a control board. The hum can be a common normal result of the relays coils being AC activated vs DC activated. Sometimes the relay contacts can get pitted/dirty by having to switch under hi loads. Recommendations are to minimize loads prior to "switching" to help the longevity of the contacts. Mounting isolation of the switch box can help or replacing with a DC coiled relay system can help as well.

TLGPE · 11-10-2012, 10:04 AM

Not sure if it's the same problem, but my MAGNETEK convertor always hums during use. It's just a fancy battery charger wit a big transformer to reduce the power down to the 12 volt level. The transformer is big and it hums. The newer convertors are solid-state and don't have the big transformer; they're lighter and quieter.

Tom

Genset · 11-10-2012, 01:43 PM

The hum noise from the transfer switch is the result of either dust or rust between the two mechanical poles when the coil pulls in the contacts, the dust/rust prevents a clean mating of the two poles and the result is humming.
This can be eliminated by either purchasing new unit or taking apart the old and cleaning the pole shoes, Not the contacts, just the moveable poles.
BTDT for 40 yrs
Dave

micki49 · 11-10-2012, 07:37 PM

You do know that there is a recall on the IOTA ITS-50R 50AMP transfer switch. That could be your problem.

Lit · 11-11-2012, 08:13 AM

I just looked at my unit, I have a ES50M-65N unit so I don't have the one that's on recall. Most likely I'll take the unit apart and clean the moving parts as suggested, when I get a chance.
Thanks for all the comments and suggestions, this is what makes this site great.