PD-5NE-BL-C - failed at installation

I hired an electrician to replace two switches with two Lutron caseta wireless dimmers (PD-5NE-BL-C - ELV).One circuit consisted of 7 x 12V 50W MR 16s, and other consisted of 4 x 12v 50W MR 16s but it was configured as a 3-way. They replaced the other switch with a mounted pico remote.They installed the two and the 3-way worked fine, the lights dimmed, they didn't buzz.The other dimmer did not work, the lights flashed briefly.The installer attempted to troubleshoot, and moved the working dimmer to the non-working circuit.That dimmer then failed, and when put pack on to its original circuit, did not work either.Lutron was phoned, and an RMA issued, but I would like to understand how two dimmers could fail?What would I have to measure in the circuit to determine if something in the lights or the transformers could be feeding back to the dimmer to cause it to fail.The electrician is not sure what type of transformer the pot lights used - they came with the house, and were installed circa 2003, so he speculated they might be MLV vs. ELV.

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Originally Posted by csl1965

I hired an electrician to replace two switches with two Lutron caseta wireless dimmers (PD-5NE-BL-C - ELV).One circuit consisted of 7 x 12V 50W MR 16s, and other consisted of 4 x 12v 50W MR 16s but it was configured as a 3-way. They replaced the other switch with a mounted pico remote.They installed the two and the 3-way worked fine, the lights dimmed, they didn't buzz.The other dimmer did not work, the lights flashed briefly.The installer attempted to troubleshoot, and moved the working dimmer to the non-working circuit.That dimmer then failed, and when put pack on to its original circuit, did not work either.Lutron was phoned, and an RMA issued, but I would like to understand how two dimmers could fail?What would I have to measure in the circuit to determine if something in the lights or the transformers could be feeding back to the dimmer to cause it to fail.The electrician is not sure what type of transformer the pot lights used - they came with the house, and were installed circa 2003, so he speculated they might be MLV vs. ELV.

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Just a guess here... using a digital electrical meter, measure voltage between the 2 wires that were attached to the dimmer and the white/neutral. You should get ~120v on one, ~0v on the other. If you get 120v on both they could be on different phases so you put 240v on the dimmer.

I've also seen the ground wire connected to the blue terminal which causes excessive current.

The first test is to put the mechanical switch back in and make sure it works.