Household electrical questions

[Carmudgeon]

Getting ready to install new smart switch so that playing pin-the-tail-on-the-donkey game with the key, in the dark, will be a thing of the past.

It's going into a 3-gang switch box, which currently has two toggles and a rotary dimmer, all 2-pole connections via screw terminals. Smart one will replace one of the toggles, and the rotary dimmer will be replaced by a more modern toggle dimmer.

New smart switch, while blessedly not needing a neutral wire like most, does have a ground lead among its pigtails, and is not self-grounding. Box is metal and connected to corrugated metal conduit.

Will have to add a ground lead, either attached by clip, or screw. And is there a way to test that the box is grounded? There are no outlets or other metal fixtures nearby.

Pulled the wall plate off, and can't tell by peeking in whether there are existing hole provisions to add a ground wire, untill I cut power and pull the switches. The box itself actually looks like it was assembled from three modular sections screwed together, but being 50 years old, I'm not sure whether it has the pre-drilled hole like many are said to.

That being the case, are those ground clips ok, or should I just plan to make use of an existing hole, if present, or create one myself? I have a 10-32 tap in the tool drawer.

Also, is there some obscure code whereby re-ordering the switch positions is prohibited? They don't make a 3-gang wall plate with the deco in the middle, so the new switch will have to be moved to the outboard position.

Lastly, I have nothing for or against wire nuts, and can use the ones provided. But I did spot the Wagos while at Home Despot, and those do seem enticing. I've seen it argued both ways.

I've also been progressively going through and replacing worn outlets, and other than them being of the backstab variety, haven't come across any obvious signs of other shortcuts in the house wiring.

 

[GMFan]

So if I understand correctly you have a metal switch box and corrugated metal electrical wiring (which I assume is BX type electrical wiring) which does not have a ground wire. Google a picture of BX electrical wiring.

If this is what you have then theoretically, the metal armour of the cable acts as your ground (assuming the BX wire is continuous and proper fittings are used between this device box and your electrical panel). The sheet of the BX cable should be connected to all metal boxes with metal fittings making an electrically continuous path which serves as your ground.

If there is no ground wire at the box you would therefore use a green grounding screw to connect the metal box to your light switch.

 

[Hall]

But I did spot the Wagos while at Home Despot, and those do seem enticing. I've seen it argued both ways.

They are UL listed (approved) along with with other international approvals so anyone that says anything about them being "unsafe", etc doesn't know what they're talking about.

 

[Blackstack]

They are UL listed (approved) along with with other international approvals so anyone that says anything about them being "unsafe", etc doesn't know what they're talking about.

Amen. I use both wire nuts and Wagos. Wagos are very nice for overhead work when you need a third arm. Attach one side of the Wago to the fixture and then the other side of the Wago to the power when you have it held up in place. I also use the lever style Wagos instead of alligator clips when testing or making temporary circuits prior to soldering or crimping everything on a trailer for example.

 

[supton]

I’ll gladly take the minor power loss at full current (which is not often) for the ease of use. I realize many will say they have used wire nuts for decades—well, I haven’t. So it would be easy for me to not get right.

 

[dlundblad]

3 cut in boxes should have a threaded hole for a ground screw. Any unused wire straps in the box you can just steal the screw from?

Is the box grounded? If not, you’re not grounding anything.

How many wires are in the Romex from the panel? 2 or 3?

 

[Donald]

The exterior of BX cable should be grounded. I would use a clip to shove down the edge of the box to add a ground.

 

[Carmudgeon]

Thanks all for the input.

The house (built in 1970) does have BX wiring throughout, not Romex, and I'm assuming (and will test) that the cabling is bonded to ground. I've seen the "worms" peek out in certain areas, and the castellated-style lock nuts inside the boxes.

I haven't gotten a full look at the box insides yet, and don't know if it has a pre-drilled hole for a ground screw, or I will need to add one. I believe clips are code compliant, and was also considering that option, but wanted to get some opinions. My inclination is to use/add a screwed in ground lead, since I lean more toward "full-measures."

The switch manufacturer does actually say that the ground can be ignored and be code compliant, provided a non-conductive wallplate and screws are used, but the latter are a rare thing and not worth the hassle to order. In practice, some seem to ignore the book, and ground, anyway.

I'll give the Wagos a try, partly for curiousity, partly to ensure idiot-proofing. It's a three-fixture light circuit that will probably see only 100W max anyway as configured, if that, so it's not a demanding situation.

But I did come to realize one situation that does need to be rectified -- the rotary dimmer in the same box actually controls a receptacle, which is verboten. It's not used as a dimmer anyway, only as a switch, so that function won't be missed.