I need some help on deciding whether the following situation is legal and safe, and EMC compliant.
I have just joined a company and am concerned about the grounding/earthing of 2 products, one products is mains operated, the other is mains/battery.
The product is housed in a plastic case.
The inside is sprayed with a conductive metal coating.
There is a metal ON/Off button (which pins go to a micro, not power), where the metal housing of the button is connected to the sprayed conductive coating.
The PCB 0volts is bonded by several wires to the sprayed metal coating.
There is an external switch mode power supply supplying 0volts and +19Volts, so the product is Low Voltage .
The power brick is a commercial well known brand (XP), and so will be compliant with the necessary EMC and safety regs.
The power brick has a 2 pin mini DIN connector plug with 0V and +19V pins, and a outer metal housing which is electrically connected through its shield to Earth on a 3 pin 240Vac L-N-E supply. the 2 power pins are not connected to the Earth shielding.
The mini DIN socket on the product has the two pins 0V and +19V wired into the electronics as you would expect. As mentioned, the 0V is connected to the "chassis" of the product.
My problem is that the mini DIN terminals for the outer metal housing ( thus earthed via the power brick) IS NOT CONNECTED TO ANYTHING.
thus the whole thing is floating.
There are USB sockets, so the product can be connected to desktop/laptop PC's. The outer metal of the USB is connected to this "0V chassis", and so if USB is plugged in a connection is made to "Earth" via the desktop PC.
The product has passed all EU EMC emission and susceptibility and ESD zapping tests.
I would have expected to see the mini DIN outer metal housing (EARTH) to be connected to the sprayed metal coating, the 0V not be connected directly to the chassis, but through a 10nf/1KV capacitor.
any thoughts ?