Last week we installed some low voltage linear lighting in some display cases in a library. We removed some old fluorescent strips which were existing and used the original circuit and 2 switches that controlled the lights.

The new lights, which were supplied by the building manager, is a 24 volt system. It now consists of 2 600 watt transformers with built in circuit breakers feeding approx. 10' of lighting per transformer.

Everything fired up fine, then I get a call the lights are out. It turns out the breaker has tripped. I check the load on the circuit and each transformer is drawing about 3.5 amps, total circuit 7 amps. So I decide to change the older SqD QO bolt on breaker.

After changing the breaker I'm discovering that the circuit still trips especially when I rapidly turn the switches on and off and not 1 particular switch. Either switch being turned on and off rapidly will cause this to trip.

I need to return tomorrow morning before the library opens to dig a little deeper. I'm wondering if a problem on the neutral might be the problem however there does not seem to be a logical explanation. The wiring is BX in very good shape (the building is about 30 years old).

Any suggestions would be appreciated.

Thanks