If you connect switch wiring to the I-PAC, nothing should happen at all, because unless the switches are pressed, the wires don't actually go anywhere, they are just open-circuits at the end.
So this would suggest that there is some problem with the wiring and it is not in fact open circuit but shorted or some other problem.
The self-test LED on the I-PAC can instantly show such problems.
I can assist if you drop me an email: andy@ultimarc.com.