I'm building an LED curtain, and trying to make it as safe as I can in limited time.

We're using WS2812B strips driven off 3 Fadecandy boards.

I've got 3x Mean Well RSP-150-5 AC-DC PSUs (Datasheet: http://www.farnell.com/datasheets/2547987.pdf ) going in the box, on the plate as shown. The box will be fed with a fused, filtered, switched, panel mount IEC inlet. The box is plastic, any metal in it will be bonded to the plate in the picture.

I'm planning on connecting earth from that inlet directly to the mounting plate.

The power supplies are screwed directly to the plate.

Is this right?

Should I connect the earth screw terminal of each power supply to the same bond point used to connect the earth from the IEC inlet?

Should I connect all -V rails on the PSUs together? They'll be connected in the USB hub/host anyways, should I give them a beefier connection in common elsewhere?

Should I connect all -V rails to the protective earth?


multiple AC-DC PSUs in one box

  • \$\begingroup\$ I recommend that you capitalise brand names and part numbers properly for legibility and clarity. If you add a link to the datasheet for the PSUs we'll be more inclined to read it and maybe find some relevant information. \$\endgroup\$
    – Transistor
    Apr 23, 2018 at 23:15
  • \$\begingroup\$ If I was being as pedantic re safety as you seem to be (not a bad idea in most cases) then I'd connect the supplied power supply case grounds to the system ground (IEC inlet ground probably). || In general situations there is a risk of earth loops due to dual ground paths from case and V- to system ground, but this should be handled by the psu manufacturer as per Micah's answer, and in this application earth loops would be unlikely (but not certain) to cause a problem. \$\endgroup\$
    – Russell McMahon
    Apr 24, 2018 at 1:08
  • \$\begingroup\$ @Russell McMahon, yep, sounds like she knows. I'm a fan of building things so they'd have as good a chance as possible of passing a compliance test, even if they'll never see one. I once built a mains powered box with lasers in it that made it through compliance testing, but I had a friendly guy at the test house helping me out with all the EMC and Safety stuff. This way is much more fun, and now it's on t'internet for everyone to read! \$\endgroup\$
    – robot-army
    Apr 24, 2018 at 8:53

1 Answer 1


You'll want the protective earth connected to all the other protective earth terminals (on your power supply units) as well as to all exposed metalwork. The power supply should have its case bonded to protective earth already, but an extra connection point directly to your metal plate would be advisable.

As for DC ground, you don't need to connect that to earth ground, and it's probably best not to connect them yourself, as the PSU should have an appropriate circuit to connect the two grounds loosely while suppressing EMI. Connect all the DC grounds together, separately from the earth grounds.


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