We now have a board design to take to prototype stage, - https://adultblogz.co.uk/buttshock-arduino-shield/
If you have a look at the board you will see a number of intrinsic safety features
- Galvanic Isolation
- SELV throughout
- Current sense on Drive side.
- Equipotential bonding of digital, drive, and EMC grounds
I will be putting an order in for 10 prototype boards, and other the next few months will be shocking myself in the name of science