Originally Posted by MDR
It is the automatic transfer switch that’s humming . I took your advice and pulled the plywood up. Is it safe to use for a couple of months as we are on the road
The humming isn't a safety concern, more of an annoyance. It could become louder or even quieter at different times, locations, and different power loads so if you hear a change in the humming, that is not a concern either (unless it is super loud perhaps). Some RV'rs have replaced theirs and I have read where some newer ones are quieter, but I don't have a recommendation for one in particular.
One tip for the transfer switch (unrelated to the humming) is to have everything that uses 120v turned off that you can (more for the higher power consumption items) when switching for shore power to gen power and when connecting\disconnecting from shore power as that will allow the transfer switch to last longer (the contacts in the switch in particular). ~CA