[Playfair]

"A Reef Scene", Yes it has been called for service on a few occassions. I mentioned in here somewhere that my original backup know belongs to another guy in our club. I needed more capacity so I ended up getting a commercial unit.

Music Maker, you could probably add the heater once the pump starts with no problems, but turning on both together could be trouble. I don't have a heater running off my backup in order to maximize the time it can run for (heaters gobble up the battery fast, you'd be looking at 3 hours instead of 10)

Grochmal, there's a reddish connector at the right of the box which gets AC in and supplies AC out either from the line or the inverter. I remotely located the backup in my basement and ran a double corded line up to the tank. AC in was provided off my tanks GFI, and AC out ran to a plug that the main return pump is powered from. The fuse is at the other end not shown in that picture, and is located on the output.

As far as the "arcing", what I think happens is this: The relay contacts weld from an instantaneous high current draw produced from a motor, resulting damage to the inverter when line power comes on. I was running a mag18 when this happened (twice), and I didn't have the resources to persue the perfect solution.

However, with a replacement inverter I tested a mag9 MANY times and ended up selling the unit to someone who uses one. It's worked several times flawlessly for him.

I don't know what the computer backups use to switch or if they solve this problem. It's possible that a large inductive load would do similar damage to them.