My afci breaker did trip so I figured the wiring was wrong. We as electrians know these breakers are sensitive. I brought up the subject to a couple of my colleagues thinking I wired it wrong. Normally there is already a plug wired in. I've only wired one other because I have been a industrial and commercial electrian for 25 yrs. I know it is not an excuse but when I saw the black and white wires coming off the terminals I though they were the transformer wires. I told them I was getting a direct short reading but that could be the meter reading through the windings of the transformer. they suggested testing it on a normal circuit. The circuit didn't trip, the thermopile just glowed and made a fizzing noise,then the puff of smoke. I found the wiring diagram after the fact but I still don't see were to hook up the 120v.