loud noisy humm in transfer switch

[MarkieBob]

My transfer switch has had a loud humm to it since new--in fact was replaced under warranty once to no avail. Unfortunately it sits near our bed, so it's bothersome at night.

my RV tech says I could try a couple other brands (I think mine is a PD 52) but could have the same problem.

Is there any danger to continued use of this one? I'm trying insulation between the switch and wall & insulation behind the cupboards now to help, and it might, but is there anything else I could try? I've tighened all wire ends, etc.

[sailor_lou]

dougrainer wrote:

Mandalay Parr wrote:
Think I would go with a different brand. BTW, the transfer switch relay should only be energized when on generator.

Maybe it's wired wrong. Mine is quiet.

Some transfer switches engage when on either source. BUT, the hum can be caused by dirty 120 input current that is not steady at 60 Hz cycles. The tell on the OP is he had it replaced and had the same hum. That points to an external cause. Doug

As Doug stated, some transfer switches are energized on either source. However, 120 is the voltage not current and although you may see some frequency drift with your onboard the generator, you will NEVER see it on the grid.

What you are hearing is the 60 cycle hum cause by the magnetic field making the enclosure and/or coils vibrate. If the vibration is within the core of the coil you may not be able to do much except to ensure it is mounted securely. If it is the enclosure, try tightening all mounting screws including the cover or installing a shock mount (ie: rubber) between the enclosure and the mounting surface.


Lou
05 Travel Supreme Envoy

[MarkieBob]

I stuffed the whole bed mat behind the pull-out cupboard and insulated it pretty well. The "hum" won't cause any lasting problems if left alone?

[Cbones]

It is common with some brands. After replacing a few under warranty, Fleetwood finally wrapped my unit with Dynamat, and now no more audible hum in the bedroom.

[dougrainer]

Mandalay Parr wrote:
Think I would go with a different brand. BTW, the transfer switch relay should only be energized when on generator.

Maybe it's wired wrong. Mine is quiet.

Some transfer switches engage when on either source. BUT, the hum can be caused by dirty 120 input current that is not steady at 60 Hz cycles. The tell on the OP is he had it replaced and had the same hum. That points to an external cause. Doug

[TechWriter]

MarkieBob wrote:
My transfer switch has had a loud humm to it since new--in fact was replaced under warranty once to no avail. Unfortunately it sits near our bed, so it's bothersome at night.

That's AC relay hum. I replaced my transfer switch with one that uses DC relays (no hum).

[univmd]

We also have a PD transfer switch under our bed. It is sometimes loud. But this year it got really annoying. So we opened cover of switch up, and discovered that we can decrease the loud hum, by stuffing a small wedge inside between the casing & actual switch block inside. This wedge tightens the entire switch block inside, thus eliminating noisy hum. We stuffed the wedge at different points while it was humming, until we found the exact point & pressure, on ours, it was the shore power side of switch inside, that hummed.

[Mandalay_Parr]

Think I would go with a different brand. BTW, the transfer switch relay should only be energized when on generator.

Maybe it's wired wrong. Mine is quiet.

[MarkieBob]

It's mounted to plastic. I put a piece of camping pad (half inch thick ) behind it--didn't see/hear a difference.

Yeah, I "hit" it too, but it only got mad at me (got louder)

[midnightsadie]

CHECK AND SEE HOW ITS MOUNTED, IF MOUNTED TO A STEEL PLATE? TAKE IT OFF AND PUT SOME RUBBER WASHERS BEHIND THE MOUNTING BOLTS. OR CAN IT BE MOVED , SOME PLACE OUT OF THE YOUR HEARING RANGE.

[GENECOP]

Not uncommon, but also not normal, ours has had a humming INTERMITANTLY since new, 4 years now, sometimes a good tap makes it go away....No danger as far as I can tell.....