Connecting circuit ground to mains ground

[The Master]

Hi, Im making a circuit that runs from a PCB transformer. Is it possible to connect the circuit ground after being rectified to the mains earth wire? The circuits use RS485 and im hoping to save on wiring

[timmers]

I take it you are trying to save a ground wire in the rs485 link and intend to use mains earth as the common reference...

Personally I would leave the "secondary side" floating to prevent any earth current loops. I would however use a Screened cable or an additional 0v reference line to complete the 3 wire link required by RS485.


Tim.

[The Master]

I see, Im going to use twisted pair for A and B but not screened. Ill keep the 0V reference wire though.

Thanks for your help