I have installed two LED pots in parallel, controlled by SPST switch. The lights are from Amazon (China?), the 14/2 wire and 200a Siemens panel are from Home Depot. The 15a breaker came with the panel.
I wired the lights by pushing the 14/2 wires into the supplied "auto-crimp" connectors.
I wired the switch(es) by adding 6" leads to all four poles. Both grounds were connected to the box and I used a marette to connect the ground from the switch.
Neutral / white was connected with a marette between switch, panel-wire and load-wire.
The panel-hot wire was connected to the bottom pole with a marette, and the load-hot wire was connected to the top pole with a marette.
If I turn the breaker on while the switch is OFF, the breaker immediately trips. If I turn the breaker on while the switch is ON, the lights turn on and everything looks good. As soon as I turn the switch off, the breaker trips. I changed out the switch, and the behaviour is consistent.
I have never seen this sort of behaviour. Where should I start looking?