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I've just bought a few of these (photo below) rocker switches (rated 16A/250VAC) with the intent of embedding them directly in a plywood desk. They'll be soldered inline between the wall socket and a 6 way extension cable to allow me to physically turn on/off the connected equipment without having to scramble around under the desk to turn them off at the wall.

rocker switch

I was going to 3d print an enclosure to keep all of the live wires tucked away, but a friend mentioned that I might need to be careful as the bare contacts (though I could heat shrink them) would be very close to the wood and the 3d printed plastic, which might pose a fire risk.

That sounds like a reasonable concern, though the actual switching mechanism is enclosed within the plastic body of the switch, so any momentary arcing should be already contained.

I don't really want a full face plate (to embed the switch in) on the top of my desk (especially as I will have 3 of these), as I'd like it as minimal as possible, so I was thinking I could route in a junction box (something like this) and cut a hole in it so the bottom of the switch pokes through; just so it's all contained properly.

I'd just like some input on whether people think it's a good idea to embed a backbox/junction box in the underside of the desk, whether it's nothing to be concerned about and I can just 3d print an enclosure and have the live contacts near the wood, or whether anyone can thing of a better option altogether?

Thanks.

OdinX
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2 Answers2

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If anything is getting hot enough to pose a fire risk just by being near wood or 3d-printed plastic, you've got big problems, and a fire risk even in a proper enclosure. Arcing isn't the concern; you won't ignite any of these materials with even a big spark.

That's not to say there's nothing to worry about. A poor connection carrying high current can start fires so you need to make sure you don't end up doing that. I'd use a proper project box, which you could rout in from the back. Project boxes / plastic enclosures from the like of RS are easier to work with than those moulded terminal boxes, and tidier. The downside is they don't usually have any strain relief built in so you need to add that.

I would either use heatshrink over soldered joins, or insulated crimps (pull-tested to make sure they're secure), and I would definitely cable tie the wires together as close as possible to the connections, such that if one came loose it couldn't get anywhere.

Further notes:

  • In some jurisdictions such DIY electrical work has insurance implications, even if it never causes a problem
  • If your desk is anything like mine, anything set into the top should be considered in the light of spill hazards. I'd mount switches in the side personally, because I'd want any in the top to be waterproof (plus I'd bury them under paper, tools etc.). What I've actually done is rigged an extension lead with a solid state relay to turn it off when I power down the PC.
  • Have you considered using a 3/4/6-gang light switch with a suitable back box? That could be all metal and earthed, or all plastic an not earthed.
Chris H
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A 3D printed box may be conductive and the box libked is not rated, and again may not be suitable.

I would go with smart switches to control the appliances. And you can either control them with your phone, PC, Alexa, Siri or build a box of low voltage switches.

Rohit Gupta
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