This device operates internally at 12VDC. It can run on D-Cell batteries. It uses a transformer-based power pack to convert A/C to DC for the unit. What possible benefit do you see in converting this (if you even could) to a 3-wire grounded system? There most likely is already a fuse incorporated into the PCB internal to the power pack. You cannot wire A/C directly to the device as it is not internally capable of using the voltage. Any ground that you placed on the device would only be effective to the power pack and would not continue on to the device itself. It seems like a waster of time and effort.