Where can I find a replacement for my reverse polarity test switch? This is the switch in the electrical panel used to test the polarity alarm. It is a Single Pole Double Throw (SPDT) On - Momentary On switch with a three blade terminal. I’m finding many “close but no cigar” replacements; the On – Momentary On function is very hard to find. In my particular instance, the switch was bleeding power causing the shore side GFI on 110 Volt hook ups to trigger.