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).
Lee You need to provide more info. 1 Are the transformers 120/24 volts? Are they on the same circuit? 2 "It now consists of 2 600 watt transformers with built in circuit breakers feeding approx. 10' of lighting per transformer" Is this the breaker that tripped or the line circuit breaker? 3 What size is the circuit breaker? 4 Is the amperage measured on the 120 volt side?
These types of transformer can draw large inrush currents. Sometimes 40 x FLA. If you have a good voltmeter you can measure the max current and see.
I'm with Bob and Tom here.... You probhably notice a "ping", or "pong" when you flip the switch? How many watts are you running on each transformer?
Are you using a decent "lighting" Transformer, or one of those buck and boost T's with a few modifcations of adding CB's from a "Manufacturer". Some of the cheaper ones will just modify a buck and boost. That will give them a very high in-rush. (As they were designed for power, not lighting...) You can try the breaker suggested, or if possible use a dimmer to ramp up the switching current, or switch seperate.
Mark Heller "Well - I oughta....." -Jackie Gleason