I am trying to control my walkway lights with motion sensor.
I am using 3 walkway lights (each 12V / 18 W, bulb model # 1141) powered by Malibu 100 Watt Power Pack (from HomeDepot -

http://www.homedepot.com/h_d1/N-5yc1vZ1xnu/R-202025778/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053) controlled by motion sensor from Lowes Hardware (http://www.homedepot.com/h_d1/N-5yc1vZ1xnu/R-100654980/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053).

Motion detector controls 120VAC feeding the transformer.
System works for few days, sometimes weeks, before either transformer burns out or motion detector dies.


Something is mismatched. I suspect that load on the motion detector is not big enough and this causes internal triac (or whatever semiconductor is controlling the output – it is not a relay) to die.

I tried to control instead a 120V AC relay with the motion sensor but load is definitely too small and it never triggers.
Any ideas other than add more lights to the output of the transformer or use bulbs with more wattage?

I am thinking that if I could find a motion detector with relay output then I could either control the primary or secondary part of the transformer without worrying about load being too small.
I have no problem using different parts if this is going to fix the problem permanently.

Any suggestions will be appreciated.

Thanks.

<Added URL tag and line breaks for readability - KISS>

Add a 10W resistor around 2K to either circuit. In parallel with your relay coil or in parallel with the transformer.

Use a 2000 (2K) to 2500 ohm >=10W chassis mount or lead resistor from DigiKey Corp. | Electronic Components Distributor | United States Home Page (http://www.digikey.com) will work. I can't directly post the search terms.

The relay method will be the safest.

If you want to use a solid state approach, a zero turn on SSR with the resistor on the input side and POSSIBLY the output side should work. Digikey p/n EZ240A12-ND

Your transformer burns out? I think you are on the right track to switch the secondary, not the primary. Have you considered X10 technology? They have wireless motion sensors which switch X10 devices using a relay.