I have a through-the-wall a/c in my kitchen, it works well enough but the on/off knob is no good, so to turn it on and off you have to plug and unplug it. More and more this has been causing sparks. I recently replaced the plug head and the outlet receptacle due to damage from this sparking. I looked for an outlet with a power switch but couldn't find one any higher than 125 volts. I'd like to put an in-line cord switch on the power line but again, I can only find them for 125 volts. Is there any other way to put some kind of external power switch on the line?