top of page

Power Supply Switch

Updated: Jun 2, 2020

I have been meaning to do this for some time. I had the power supply and the switch but never seemed to get the time to put it all together. Plus the fact, it meant playing with hard-hitting electricity. It put me off because I am no electrician!

But then I started to build the Piper 3D printer and I thought I would make this project just for that. I was trying to make this printer the “most perfect” printer that I had. I have built four printers from “kits” and after doing that many of them you start to get an idea of what the perfect kit might be. The Piper comes close to that because all the design has been done for you. All you have to do is print and assemble it in the best way possible. So that brings me nicely to this little post. Whilst it isn’t about the Piper 3D printer it is about a way to slap a switch to one of those power supplies that you tend to use in order to get 3D printers working.

First, the warning if you want to follow this guide you should understand that you will be working with potentially lethal electric current. I implore you to be careful and only work within your own knowledge boundaries. If you don’t know what you are doing please please please get someone else to do the work for you. I asked someone the correct way based on the fact they knew what they were doing. Please do the same. Don’t take this guide as gospel either, do your own checking if you feel the need too.

With that out of the way let’s get on with this switch. As you may or may not know I live in England. You know the place where it always rains we constantly moan about the weather and Brexit is tearing us apart. The reason I mention this is because of colour (No not the fact that we spell the word correctly) but the colour of the wires that we use here. In England, our household electrical wires are coloured as follows.

  1. Brown is Live

  2. Blue is Neutral

  3. Green is Earth

In the US as a comparison it’s

  1. Black is Live

  2. White is Neutral

  3. Green (or bare) is Earth

Europe has the same colour for wiring as the British. I think they were trying to get a standard across the board. You need to check these facts are true before following this guide. I don’t want any mishaps while you are following my post. OK, I’ll get on with it now.

As I said, I had the parts I needed. A 3D printed housing some time and a friend just to verify what I was doing wasn’t going to hurt me.


You will need some wire to go along with this little project. I stripped off some wire from an old PC power lead that I had laying around. I thought if that’s good enough to power a PC then it’s going to do me too. I got the switch from somewhere else, but one like it can be found Here

I then soldered some female spade connectors to each end so they would fit on nice and tight.


I then wrapped a piece of shrink tube near the ends to give it a little strength. I’ll show you the wiring layout of the switch in the pictures below.

As you can see you need to loop the wires from the live input side to the switch side. as seen below. As you look at the picture the wires on the right are coming from the power cord. the Brown (live) and blue (neutral) then go off to one end of the rocker switch. The green (earth) wire goes from that terminal to the earth post of the 3D printer power supply/brick.

The other two terminals of the switch will have corresponding coloured wires going from the switch to the other posts on the 3D printer power supply. The picture below is how it looks with all wires attached before being wired up to the power supply.

Once more just so you understand…

The top wires (the looped ones) bring power from the power cord to the top two terminals of the switch. So when the switch is off it doesn’t allow power to flow to the bottom set of brown and blue wires. This is off!

Then, when you move the switch you allow electricity to flow to those bottom wires thus allowing the power brick to power up.

Only when you are 100% happy that you have wired it up correctly can you start putting it all together to test.

I realised that I had not cut out an access hole for the other wires that would be coming out to power the RAMPS board. I had to cut these out with a sharp knife, lucky for me the printed part wasn’t too thick (unlike me) I also had to trim up the switch hole as this was a little too tight.

When that was done I popped the switch through the case that I had printed and made sure it was sitting nice and tight in the hole. I will put some hot glue around the switch when I finally test it.


I then soldered some proper connectors to the power leads that would power up the RAMPS board. The idea being that once this was all bolted in place I see no reason with needing to go in there again. I had some crimp spade ends, so I cut away the plastic covers to solder wire to them on for extra secure connections back to the power brick.


Now it was time to connect all the wires from the switch to the corresponding connections of the power brick and the RAMPS wire and feed that out of the access hole I had cut earlier. Below you can see where the wires fix to each post of the power brick.

Here it is all bolted together. As you can see there is plenty of room in the part that I printed (found it on Thingiverse Here) although I did have to change it slightly because of the size of the maker’s original switch he was using.

Now it’s time to test it. If all goes well I should see 24 volt on the multi meter.


Well, that was fun and I can now just turn off the power without having to rush to find the plug when something goes wrong. Thanks for reading.

Share this:

  1. Tweet

  2. More

  1. WhatsApp

  2. Email

#3dprinting #Learnabout3Dprinting #3DCADDesign #3dprinter #3dprinters

7 views0 comments

Recent Posts

See All
bottom of page