making power inverter work 2 ways.

Peter that's what I said though I was switching through the ground side. I still don't think you should leave any inverter permanently switched on. too much juice required to feed the inverter before even any loads are applied.

Ooops - my bad for repeating. Sorry! I agree with not leaving inverters on (as opposed to having its on-switch permanently on because it is controlled via a relay) - many inverters draw several Watts even with no load. But that is no different to any non-alarmed manual-only switch (viz. my audio, and - until I fitted the buzzer last week - my car's lighting). And electricd7 seems to have no problems remembering to turn it off. (Just as I do with my audio and lights - until I don't!) But if electricd7 did, then maybe a spare battery (as I have) else a low-voltage cutout. In electricd7's case, I'd use a $20 MW728 to drive the relay using 2 push-buttons instead of the SPST on-off switch, ie, a push-button to turn the inverter on until the 2nd push-button is pressed OR the low-voltage sensor (MW728) switches off (and doesn't come back on until the ON push-button is pressed). Then if electricd7 does forget to turn the inverter off, who cares?