Clear Junction Box Cover
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Kind of a tangential question.
The controller for the backup heat for my Chiltrix heat pump is in a regular 4×4 junction box, I’ve attached a picture. Picture upload isn’t working right now, I’ll attach one when I can. On the controller is a LED to indicate that it’s on. With a cover on the junction box you can’t see the LED. I’d like to be able to see it, well, just because.
I haven’t been able to find a clear or translucent junction box cover. I thought maybe a cover with a knockout in the center would work, the hole would be in the right spot, but I haven’t been able to find a clear or transparent knockout plug. I even thought of looking for a clear plastic plug that was threaded for 1/2″ NPT pipe and using that with a locknut, but I can’t find that either.
I can’t replace the junction box, the controller is actually assembled around it with a heat sink on the outside.
Any ideas?
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Replies
If you don't care about code, just screw some plexiglass to the front. Is it a plastic 4x4? You might find an outdoor box that has a clear lid that your could rig up.
> If you don't care about code, just screw some plexiglass to the front.
Gonna have to second this. Hand draw a little UL logo on it to make it official. :-)
I'm not aware of any covers like that for regular boxes. Usually what is done for industrial controls with indicators is to use a box with a clear window, but those boxes aren't cheap:
https://www.grainger.com/category/electrical/electrical-boxes-enclosures/enclosures-and-accessories/enclosures/electrical-enclosures?attrs=Solid+%2F+Clear+Cover%7CClear~ATTRS&filters=attrs%2CwebParentSkuKey&searchQuery=clear+junction+box&webParentSkuKey=WP8338059&sst=4&gwwRemoveElement=true
Those boxes are probably cheaper from an electrical supply house than they are from Grainger though.
Your best option is probably to get a piece of 1/8" clear polycarbonate sheet, trace a 4" blank cover for your junction box, then cut out your own clear cover from that piece of polycarbonate sheet. You can get small pieces of this material here:
https://www.amazon.com/Falken-Design-Polycarbonate-Lexan-Sheet/dp/B07NRDVGZM/ref=sr_1_4?crid=225V3G0VRGHB9&keywords=1%2F8%2Bpolycarbonate&qid=1696879807&sprefix=1%2F8%2Bpolycarbonate%2Caps%2C97&sr=8-4&th=1
You'd probably be OK with 1/8" or 3/32" polycarbonate, but I'd use the 1/8" myself. This stuff is relatively easy to work with, you can cut it with regular jigsaw blades, drill it with regular drill bits, etc. It's also fairly inexpensive. Technically making your own cover like this violates UL, but polycarbonate is a UL recognized material for this kind of application so you shouldn't have any problems in practice.
BTW, do NOT use "plexiglas", which is Rohm and Haas' trademark for "acrylic". The reason for this is that acrylic is much more brittle than polycarbonate, and because of this is a poor choice for this application.
Bill
DC,
https://www.jwwinco.com/en-us/products/3.5-Controlling-venting-sealing-of-liquids-and-gases/Oil-sight-glasses/EN-546.1-Technopolymer-Plastic-Dome-Shaped-Plastic-Fluid-Level-Sight-Glasses-with-Marking-Ring
https://www.jwwinco.com/en-us/products/3.5-Controlling-venting-sealing-of-liquids-and-gases/Oil-sight-glasses/EN-546.6-ATEX-Explosion-Protective-Plastic-Dome-Shaped-Fluid-Level-Sight-Glasses
That's perfect. Thanks. I knew someone here would know.
There is one on my Makita compressor.
I very much approve of this project. These are the kinds of things that make (obsessive) builders happy!
Of course it's not UL-listed for that purpose. I'll have to keep a listed cap handy in case an inspector is nearby.
DC,
Any decent inspector would appreciate the ingenuity.
It's actually unusual for inspectors to look for UL (and similar) test agency marks. Usually they just look for things to "look right", and if things don't "look right", the inspectors will sometimes dig deeper. That little inspection cap mounted in a correct size hole in a blank cover, with the obvious purpose of allowing a status light inside to be visible, is very unlikely to even get a second look. I wouldn't worry about it. I also don't see how that inspection cap could possibly be a safety issue. That cap would probably be able to pass UL testing, if it was submitted for testing ($$ and $$$).
Bill
A standard 4x4 box should accept a clear weatherproof cover, here's one for less than $10. Avoid the "in use" covers, which will be a few inches deep to allow a cord to be plugged in while the cover is closed.
https://www.amazon.com/MM1410C-Configurations-Vertical-Weatherproof-Plastic/dp/B005GOGCW0