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I am making a project that will fit into a 3D printed enclosure. I want to keep the project neat so I will have just one extension cord running from the wall (120VAC) into the enclosure to power all of my electronics. One of my devices requires 12VDC so in order to save space inside my constrained enclosure, I thought that I could solder wires directly to the AC input prongs of the power supply and heat shrink & electrical tape over that. The reason for not directly plugging it into the female end of the single extension cord entering the enclosure is that I need two additional items to be plugged into the cord that I was going to use wire nuts for. This 12VDC adapter will be powering 1A for only a few minutes at a time, maybe once per day.

Is it safe to solder the wires to the AC input prongs of the 12VDC supply?

Solder connection

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  • \$\begingroup\$ One would think that if you are using an AC powered 12V power supply that the AC prongs would plug into a wall socket and the 12V output would enter your enclosure. Please explain why you need to solder directly to the AC prongs. \$\endgroup\$ – Barry Jul 30 '17 at 21:51
  • \$\begingroup\$ I think that the supply provides 12VAC... But it is not clear at all. \$\endgroup\$ – Vladimir Cravero Jul 30 '17 at 22:04
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    \$\begingroup\$ You have a power supply. It has input and output power. Please edit your question to include the voltage and whether it is AC or DC for both input and output power. Then clarify whether the prongs you are planning to solder and tape over are input or output power prongs. A picture of the supply would also help a lot. \$\endgroup\$ – mkeith Jul 30 '17 at 22:23
  • \$\begingroup\$ If you project is commercial, you are creating a legal nightmare for yourself by doing this \$\endgroup\$ – Dirk Bruere Aug 1 '17 at 9:00
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Use a supply intended to be wired to

As you can tell, "wall warts" are not intended to have chassis wiring hooked up to their inputs. An easier and safer approach, provided you have the small amount of additional chassis space (3" by 2" by 1.1" for the Mean Well linked below vs. 2.8" by 1.9" by 1.25" or so for a wall wart) and the ability to bring a ground conductor (3 prong cord) into what you're building, would be to use a chassis mount enclosed supply, such as the Mean Well RM-15-12 (which is under $8 in onesies via Mouser). These supplies have screw terminal inputs that are intended to be chassis wired to and screw holes for mounting screws so they can be attached solidly to the case instead of flapping around in the breeze like your wall-wart would.

representative image of chassis mount supply

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  • \$\begingroup\$ Great suggestion, I cannot believe this didn't cross my mind! The only probably issue I see is -- do I have to connect the Earth connection on the AC input side of the supply? For design reasons, I don't have a cord with an Earth connection coming into my enclosure, just a two wire cable. The only reason I ask is that I've already 3D printed my enclosure with the two wire cable in mind. It would be more time in CAD and many more hours of printing... :( \$\endgroup\$ – Owen Aug 1 '17 at 3:46
  • \$\begingroup\$ @Owen -- keep your eyes peeled -- there are some Class II (double insulated) chassis mount supplies out there, but they're often medical grade, which means they're a bit costlier \$\endgroup\$ – ThreePhaseEel Aug 1 '17 at 11:40

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