Progressive EMS Hum
Installed an EMS-HW50C surge and electrical protector a couple of years ago. It's between the transfer switch and the main breaker box so it protects for both shore power and generator power. It always had a 60 hz hum that was fairly loud and it's in the compartment at the foot of the bed. Sent the company an email about that, got a reply "what's your address". Gave them my home address and then got a couple of email invoices with zero charge. Thought they were sending me a replacement unit. When I got home and went through the mail, I had 2 identical packages each with a relay inside. No instructions, I suppose they thought I would know how to replace the old one; I did. Much less hum now, but still a tiny bit. I had to disconnect the main wiring and remove the unit in order to do it. There were several wires with push on connectors from the PC board to the relay coil that I carefully marked and took pictures of to make sure I put them back correctly. I can not see any difference between the old relay and the new relays. The coil is operated by 120vac, so with the relay not installed you can apply 120vac to the coil terminals and listen for hum and watch it close. I emailed and asked if they wanted the extra relay back and got a reply "no worries". Lifetime do it yourself warranty.
Topic: Progressive EMS Hum