Hi all, I was just doing some maintenance on my boat (nothing electrical) when I heard a loud electrical noise coming from my inverter. It will make the noise for 20 - 30 seconds then stop. The inverter was not on, and I turned shore power off, but the noise continued. 

The only thing I can think of is the inverter is dying, a Prosine 1800. I will disconnect it to avoid the risk of burning the boat down.