Elvis, I have operated door locks on as small as 10 amp circuit breakers. Then as you know, if they hang up for any reason the breaker will trip before the module / relays inside burns up. That has been my experience. Don't run them on 20,30,or 40 amps. You will be asking for trouble. John Hervey << The solenoids aren'd worn out or something similar. They simply are burned inside ! the coating / insulation of the wire is melted away and now the current makes it like JZD said - it cuts corners..also called short circuit ! Why ? because a relay was stuck and toasted the wire. If one is bad, the other one isn't much better because the are connected to the same relay. That's a common problem, do your homework and you'll find the problem and solution. >>