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Topic: 30 amp transfer switch HUMMING! (Read 703 times) previous topic - next topic

30 amp transfer switch HUMMING!

Hello all,
We had both transfer switches replaced in June while we were in Baytown Texas. Was wondering if we have a defective unit on the inverter 30 amp unit. It has a pretty consistent low grade humming sound coming from the foot of our bed. One of the new inverters actually had a disclaimer that warned of noise and stated it wasn't indicative of a problem with the switch. Want to be able to assure my D W that all is well! Anyone with knowledge of or first hand experience with such racket?
                          Thanks in advance!
Tom
1998 U320 40'

Re: 30 amp transfer switch HUMMING!

Reply #1 –
Tom,

I feel your pain.  That "HUMMMMMMMMMmmmmm........" from under the bed drove us crazy, especially at night when we were trying to sleep.

You are not alone.  Google "transfer switch humming" to read about all the complaints.  For instance:

Automatic transfer switch loud buzzing keeps us awake! - iRV2 Forums

One solution - replace your ATS with a DC contactor model.  Several 50A models available...not sure if they make a 30A.  One example:

Automatic Surge Protected Transfer Switch

OR, you could try my solution: replace the ATS with a manual switch.  See this thread for details:

Transfer switch questions
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 30 amp transfer switch HUMMING!

Reply #2 –
Sounds like the coach isn't in any immediate danger. Definitely want to look into manual unit in the future although this seems to be coming from the lower inverter side switch. I think the main has to pass through this box somehow on its way to the panel.
Tom
1998 U320 40'

Re: 30 amp transfer switch HUMMING!

Reply #3 –
Since you suspect the 30A (inverter) transfer switch is making the noise, not sure if my "manual switch" solution would work.  It was our main ATS (that switches between shore and generator power) that was driving us crazy.  It made the humming noise when we were on shore power (which is most of the time), so I assume it was "energized" in that position.  It may possibly have been totally silent in the generator position, but with the generator running who could tell?

When you hear the humming, are you running on inverter, or plugged into shore power?  I would think the inverter transfer switch would only be "energized" when running on inverter, but I may be wrong.  I'm not super sharp on electrical stuff...
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 30 amp transfer switch HUMMING!

Reply #4 –
We're plugged in currently. Full tin as we build our barnominium. Sounds like replacing our xantrex inverter to state of the art Magnum could do away with smaller transfer switch all together!
Tom
1998 U320 40'

Re: 30 amp transfer switch HUMMING!

Reply #5 –
Quote from: TAS69 –
Sounds like replacing our xantrex inverter to state of the art Magnum could do away with smaller transfer switch all together!
Yes, that is correct.  That is exactly what we did, which did eliminate the 2nd transfer switch.  Now we have none...total silence.  ^.^d
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 30 amp transfer switch HUMMING!

Reply #6 –
Are we "safe" for time being?
Tom
1998 U320 40'

Re: 30 amp transfer switch HUMMING!

Reply #7 –
Quote from: TAS69 –
Are we "safe" for time being?
Way too many variables in life for anyone to answer that question...

BUT,

for what it's worth, I have never read anywhere of any "serious" danger from the failure of ATS.  It usually just stops working.  When opened up, there may be blackened contacts and components, but I have never heard of smoke or fire.  Other more experienced members - please correct me if I am wrong.

Your "humming" ATS may keep on making noise and working fine for a long time, or it may fail tomorrow.  Since your ATS is practically brand new, I doubt there is any problem with dirt or dust inside the case.  The usual advice here is to check (with ALL power sources disconnected) for loose wiring connections inside the box.  If everything is tight, and there is no bad "electrical" smell, and nothing looks black or melted, then the ATS is probably fine.  You'll just have to live with the noise until you do something different.  This is all just my (totally unqualified) opinion, so take it for what it is worth!  8)

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: 30 amp transfer switch HUMMING!

Reply #8 –
Quote from: Chuck & Jeannie –
  and there is no bad "electrical" smell, and nothing looks black or melted, then the ATS is probably fine. 

Yup, we took a "hit" while on SP last year, never did find out what caused it; external/internal, but it sure fried the ATS and our shore power cords and coach connection. As Chuck says, "That Smell" is the tip-off that this could be serious. We had no fire, but it was months before the coach smelled normal. We now have a Progressive PT-50C EMS on the SP pedestal and I'm thinking of having a EMS installed on the gen-set circuit, as well.  ^.^d
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
Previous: 1983 Airstream 310 turbo diesel, 1979 Airstream 280 turbo diesel
                                      Build # 4297
                                      PNW natives
                      Home base:  'Cactus Hug' (Ajo, Arizona)
                        DW Judy & Chet the wonder dog
                        Full-Timers 'Sailing the asphalt sea'

Re: 30 amp transfer switch HUMMING!

Reply #9 –
Thanks Guys
Tom
1998 U320 40'