I want to do something the instruction manual for my inverter says not to. I want to hook it up to a transfer switch to power some circuits so I don't have to use extension cords when I need to run off batteries when the utility power is down.
I have a Samlex SSW-1000-12A inverter whose manual says: "WARNING: Do not connect directly to AC distribution wiring. This inverter is NOT grid interactive." That's not a surprise, I know better than to try a plug it into a live circuit, thus the transfer switch.
It also says: "Do not connect the power inverter to any AC load circuit in which the Neutral conductor is connected to Ground (Earth) or to the Negative DC (battery) source." That's more of a problem since my house wiring bonds neutral and ground, of course.
I'm guessing this is a fairly common problem. Is there a common solution other than "don't do that"?
Hooking my inverter to a transfer switch isn't as odd as it may sound. The transfer switch is an APC UTS6H, an automatic transfer switch with connections for both generator and battery backed UPS. This model is a varient for Honda that accepts a L5-30 120V connection for a Honda EU generator, I have an EU 3000is. The UPS connection is probably intended for a standard APC UPS, but I figure my inverter with 380AH of battery behind it will give me a lot more time before I need to run the generator and recharge the batteries.
I first hooked the switch to a standard 750VA UPS, which worked just fine. I then tried plugging it into my inverter. I immediately heard a pop and no power from the inverter. The GFCI outlet on the inverter tripped. The GFCI tripped even when hooked up through a switched off power switch since the neutral and ground weren't switched off. I finally used a two prong extension cord without a ground wire to connect the inverter to the switch. That works without the inverter complaining. It works, but is it a good way to handle the problem?
Other than the problem with the GFCI on the inverter I'm pleased with the setup. If power fails the switch automatically transfers the load from up to 5 circuits to the inverter. When I get out the generator and fire it up the loads are transferred to it and I can recharge the batteries. I can now run my gas furnace when the generator is on, though that's too much for the inverter. The switch is configured to only run the furnace circuit off the generator. Depending on how long I want the batteries to last I can configure the switch to just run the fridge circuit from the inverter or to include the TV room, computer room, and bedroom.
I'm just worried I've violated some important safety rule by hooking my inverter to the switch without a ground wire. I also haven't gotten around to making a proper ground for the battery system. Possibly once I do that I'll have the same problem since the ground on the inverter will then be connected to the same ground as the house wiring. Do I need to remove the GFCI outlets from the inverter or defeat it in some way?