In California, in a metal gang box with the line ground attached to the box with a ground screw, I understand that I don't need to attach a ground wire to a switch (screwed tight, captive washers removed).

But I do need to ground the load conductor directly to the box? Is it acceptable to attach the load ground to the switch ground screw?

Or must I attach it more directly to the box (such as with a clip, nut, etc)

  • 1
    I'm not sure if it would be against code, but why not just wire nut it to the incoming ground wire, and pigtail that to the box? – Nate S. Apr 11 '19 at 22:28
  • Because if I can attach the load ground to the switch them no wire nuts are required for the ground at all. – Matthew Apr 12 '19 at 1:58

At switches

Grounds at switches must be pigtailed to the box, then all the grounds from all the cables joined to the box with a wire nut.

If you don't want to use wire nuts, you could a) use box clips on the edge of the box, b) drill and tap any #10-32 holes in the back of the box for each ground wire and land it on the screw.

You cannot land one wire on the box and one wire on the switch. This defeats the entire purpose of pigtailing grounds; ground paths should remain continuous even if you remove a device.

At luminaires

It depends on how the luminaire is built, and you have to make a case-by-case judgment call.

For instance some luminaires have two ground wires -- one for the ceiling rose, and another one for the lamp proper which is on the end of a chain or cable. Chains are not valid grounding paths! In that case, you can ground the rose via the metal box, but must wire the ground that runs down the chain.

If the luminaire has some plastic and some metal parts, that problem may recur.

  • I'm actually just concerned with the box where the switch is. – Matthew Apr 12 '19 at 1:57
  • +1 thanks! Is there some relevant code section you can cite? – Matthew Apr 12 '19 at 20:57
  • NEC 250.148B... this – Harper - Reinstate Monica Apr 12 '19 at 21:16

No... A loads ground needs to be secured to the loads structure then directly bonded to the grounding bus within the service panel... The grounding screw is for bonding the switch... Which use of a jumper is then a popular method of tying into the grounding circuit, hence keeping the circuit bonded...

  • Can you cite anything in the NEC that prohibits what the OP describes? – ThreePhaseEel May 21 '19 at 0:04

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