I want to create a steampunk-themed chandelier, including a steampunk-look switch on the wall. Is there a fundamental difference between the standard light switches sold for home lighting and a similarly-specced bat handled light switch that is sometimes used on lamps and electrical equipment? The attached switch is rated 20amps at 125vac so I would think it was appropriate for my purpose. The only thing it doesn't have is a ground screw which might be the stopper unless there's a way to add a grounding wire to the metal part of the switch. Would someone with ACTUAL electrical knowledge (not just someone without an imagination ;) ) weigh in on this one? I asked somewhere else and the person said it would work fine but in another forum people said no (but I don't believe they are electricians since it was on Amazon and they didn't give any reason it wouldn't work). It seems like an artificial disqualification to say this wouldn't work just because the handle looks different than a normal light switch. Are the guts exactly the same? Switches are pretty simple mechanisms so seems like they would be.
The ONLY way this would be code complaint (legal) and safe is if the switch were solidly mounted to a metal plate, which would in turn be mounted to a grounded metal box. If you have plastic boxes there will be no way to ground the plate through the box.
NO! Soldering is NOT an option as this is expressly forbidden in the code. You MUST have a solid mechanical connection even before soldering. Having said this there is no means or provision for any sort of mechanical connection to that switch or to a switch plate, unless of course you nut and bolt the ground wire to the plate, but this adds a visible screw head to the finish side of the plate.
Almost certainly you'd need to get a stainless steel blank plate and drill your own hole.
Not all UL labels are made equal!
Using such a device in a wall application may appear fine if grounding and bonding concerns are handled (through the cover plate and box, or the 1/2" ID ring terminal ArchonOSX suggested, or better yet, something like an APEM U187, which is basically a dedicated grounding ring terminal with a quick-connect tab for the actual ground connection); however, there's a very subtle Code compliance "gotcha" at play here.
Switches like what you describe are UL component recognized, which means that UL has inspected the manufacturer and says they're OK when used within their stated ratings when used within a larger UL-listed product, such as an appliance. This saves the appliance manufacturer and UL a bunch of work because then the UL listing process for the appliance doesn't have to worry as much about "what if the switch does something weird?" However, even though it is technically a UL stamp of approval, it is not equivalent to the full UL listing required for a product to be used stand-alone with house mains wiring as per the NEC, and this may cause your AHJ some heartburn, as most electrical inspectors aren't set up to figure out if a gizmo is safe, but instead rely on UL listing for that.
While this doesn't answer your question directly, it offers a safe alternative.
In the field we sometimes come across situations that require non standard ways to turn off and on lamps. For example, using a magnetic contactor to trigger a closet light, or similar.
This is usually accomplished by using a 120/12V relay. The 12V can safely be ran on existing wires to power almost any type of switch.
Even better to simplify the process some genius came up with the idea of a self contained relay with a built-in step down transformer, and to top it off its UL approved.
The area that you should be concerned with is will the added weight of the object cause any part of the switch to fail due to increased stresses. Depending on the switch material (solid metal or hollow plastic?) and how the object is attached (drill an opening through the switch for a fastener or gluing) should be considered. I don't recall any articles in the NEC stating you can't use a bat in place of a toggle switch, but than again the NEC book I refer to is copyrighted 1999.
If you really want to go steam punk, use a Bakelite throw switch. Of course, you would have to have it trigger a low voltage relay.
No, you can't. Unless you can ground any metal part that is designed to come in contact with a person, you run the risk of that part becoming energized and creating a hazard.
If the metal part of that SPST toggle were to become energized, the switch would just sit there in the wall energized, waiting for you to become a path to ground. That's not .. safe :)
Fortunately, there are options; use a non-conductive switch that's properly rated (15A @ 120V), or a metal one that has a grounding connection.
The main NEC guidance to watch out for here is all wiring devices (switches, receptacles, etc) must be listed and approved for the purpose you're intending. So, check the UL rating, and make sure that the switch can be grounded if any parts that can touch the user are conductive.
You could also use a contactor (normally open) that closes when 12V DC is applied to it, and use whatever switch you want to control the contactor. Basically, the contactor becomes the 120 V switch, and you turn that on by applying low voltage to it. But that's probably a bit too ambitious for simply changing the decor of a switch :)
answering the concerns in @Linnea Mueller's comments
Regarding code compliance - @Tim Post is right. In a nutshell - local codes require NEC compliance, NEC specifies that the switch has to be listed (by UL or other listing company). The switch isn't listed for the purpose so it's illegal. Maybe you're a maverick and don't care! But a lot of electrical mavericks have burned down their house or died of electrocution.
So what is this switch good for? The switch is suitable for use with low voltages, there wouldn't be any worry about grounding. It may be suitable for use with higher voltages in an industrial setting, or as a component of an appliance or something. In those uses, the grounding could be fine if the switch body is bonded to the metal frame of the equipment, which is in turn grounded by the device's wiring, (which is in turn powered by a NEC compliant power distribution system...)
Note that if you use this switch with a metal cover plate, you'll be bonding the switch body to the cover, so if there is a wiring fault, the whole plate could be hot.
What if you used a metal plate and grounded the plate inside the box? It will never be listed or code compliant, but is it safe? The body of the switch is bonded to the plate, and the plate is bonded to ground. Can you now rest easy that it's safe?
Are you sure the switch is rated for the temperatures that will be generated inside the box? A lot of fires have started because some component couldn't take the heat.
Are you sure the switch body and retaining collar are of compatible metals that won't corrode over time and lose that bond?
Are you sure that your jinky attachment of the ground wire to the plate won't break lose while you're putting the cover on? If not, will it hold up over time?
When you follow the code, you're assuring that all these concerns have been addressed, and maybe a lot of others you haven't even thought about.