Connecting a PhilipsHue led output to a relay
simulate this circuit &ndash; Schematic created using CircuitLab

From the information you have provided a Zener diode would suffice. It won't conduct until the voltage exceeds the breakdown voltage. I'm suggesting a 15 V type to give a bit of margin since you have plenty of "headroom".

Power dissipation will be \$ V_Z \times I_{IN} \$ so do your calcultations!