XJ12-300 Electrical Safety

[Arthur-UK]

I have been making a few changes on my recently acquired Mill.
It is the latest version with an IGBT Inverter driven Brushless motor and Belt Drive.

I discovered that the earth wire from the mains lead is only connected to the Aluminium Heatsink, and this is with a self tapper into the plastic case.
The Heatsink is floating, it is not connected to the Mills metalwork, so there is no earth connection to the Mill.
You can check if yours is the same simply by connecting an ohmeter or buzzer from the mains plug earth pin to the metal body.

As if that was not bad enough, the cartridge fuse in the control box is connected to the incoming Mains Neutral, so if it blows it leaves the whole of the wiring still live.
Of course it carries the CE mark, but clearly has never been tested.

The picture shows the green earth wire, trapped under a washer that touches the heatsink. The box is plastic.

 

[markba633csi]

Certainly needs an additional ground wire (or two) and a fuse rewire

 

[mksj]

Typically there would be a ground to the motor connected to the VFD, the motor would be grounded to the machine. In either case, good practice is to have a star or common buss ground at the entry into the enclosure and all grounds including the VFD are attached with the appropriately sized gauge wire. CE, ISO standard, etc. are pretty meaningless these days on many of these cheap/generic machines. They hold little to no liability for their products in most cases.