This question has a bit of application background so please bear with me:

I'm working on a LED lighting system. The controller (MCU, led drivers and led supply) will be powered by a single DC switching power supply. The luminaries are the typical aluminum with leds in series PCB attached to a large heatsink and optics. The luminaries will be mounted on cable trays.

The problem is that the DC ground of the led PCBs is intentionally connected to the heatsinks by mounting screws (not my decision not anything I can do about it). In turn, the heatsink is part of the luminary chassis itself and will be in touch with any other metal supporting it, in this case the cable tray. For security reasons, the tray is connected to Protective Earth (as the luminary chassis should be..)

This, once mounted, will make an unintended connection of DC Ground to PE.

So, I'd need any advice in the following:

1) Is this installation viable? I mean, suppose a leak that goes to PE, that could affect DC grounding or even destroy the electronics, am I right?

2) Will this connection create AC noise on the DC Ground?

3) Since this connection will be made unintentionally at the "chassis" of the appliances (heatsinks, trays), should I intentionally make a lowest impedance possible connection of PE to DC Ground at the controller PCB?

This all sounds like a very bad idea, but I'm not 100% sure nor have strong arguments to argue with my boss about this, so any expert advice will be highly appreciated.

  • \$\begingroup\$ What part of the world are you in? I.e. what electrical code applies? \$\endgroup\$ – Bob Jacobsen Jun 6 '18 at 0:52
  • \$\begingroup\$ I'm in Argentina. Mains is 220 V with PE on each outlet and differential circuit breaker mandatory. Electrical code equivalent to IEC 60364-4-41. These luminaries (approved by the local authorities) have DC ground at chassis. To clarify, I'm not interested on security issues, but on the kind of effects discussed on the link below applied to the incidental PE/DC ground connections outside the controller pcb. electronics.stackexchange.com/questions/19561/… \$\endgroup\$ – conejoroy Jun 6 '18 at 4:56

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