Raspberry Pi 4B LinuxCNC: Wiring a Fused and Switched 10 A IEC C14 Male Socket, Emergency Stop and 10 A IEC C13 Female Line Plug

I have recently learned that we can use a fused and switched 10 A IEC C14 male socket and a 10 A IEC C13 female line plug to bring mains AC power into the control box. This simplifies the wiring quite a bit. It also makes the emergency stop a completely independent component. I had some minor difficulties while learning how to wire these new components. This article is not a tutorial; I am documenting my learning process, assisted by ChatGPT, to arrive at the final correct wiring.

🐧 Index of the Complete Series.


Raspberry Pi 4B LinuxCNC: Wiring a Fused and Switched 10 A IEC C14 Male Socket, Emergency Stop and 10 A IEC C13 Female Line Plug

I am just an ordinary computer programmer and not trained in any of the electronic engineering disciplines. This LinuxCNC project is a learning process for me. This post is not meant to be a tutorial or instructional guide; it is my own documentation so I will not forget what I have learned.

I am not to be held responsible for any damages or injuries resulting from using the information presented in this post.

💡 These new components are part of the main power wiring discussed in the article Raspberry Pi 4B LinuxCNC: Main Power Distribution (Wiring). They replace the Main Switch and 6.3 A 5 × 20 mm (M205) 250 V Fuse Holder discussed in that article. This article updates the original article. Having a separate article makes it much more convenient to cover the new components in detail. After this article is published, the original article will be updated to reference it as an update.

❶ The Emergency Stop Button, C14 Male Socket, and C13 Female Line Plug

⓵ The emergency stop button is the same one as discussed in the article: Push Buttons Switch 1NO + 1NC e-stop Push Button AU Emergency Stop Shut Off — it provides one Normally Open (NO) and one Normally Closed (NC) contact.

⓶ I bought the C14 male socket locally, in store: C14 Male Socket Chassis Snap-In Fused Switched 10A IEC. ChatGPT suggested that I should confirm with the vendor that the fuse is in the Live/Active conductor, which the vendor support team confirmed via email.

Using this panel-mounted socket means that the control box no longer needs to have the emergency stop and the main switch permanently attached, as previously discussed.

⓷ I also bought the C13 female line plug at the same time, locally and in store: C13 Female Line Mains Plug 10A IEC.

❷ Wirings

⓵ Let’s start with
C14 Male Socket Chassis Snap-In Fused Switched 10A IEC — there are quite a few similar components that offer the same functionality. Apart from recognising that it is similar to the PC power supply socket, I know nothing about it. I watched the following YouTube videos to learn more:

From the videos it was not clear which pair of the switch terminals is used for the Live and Neutral conductors: the top and bottom pairs, or the left and right pairs? ChatGPT systematically suggested using a multimetre to test continuity between the switch terminals. I marked the 7 (seven) terminals as shown in the image below:

The Earth and Neutral terminals are clearly marked on the case; it follows that the remaining terminal is the Live terminal. The continuity tests were carried out without the fuse installed.

The switch is OFF: there is no continuity between any of the T1, T2, T3 and T4 terminals. This is to be expected.
The switch is ON: there is continuity between T1 and T3, and between T2 and T4. That is, T1 ➜ T3 is pole 1, and T2 ➜ T4 is pole 2.

I choose to use pole 1 for Live, and pole 2 for Neutral. The final wiring is illustrated in the image below:

💡 Please note that the fuse holder has two slots. The fuse must be installed in the back (inner) slot. I found that I needed to push the holder back in firmly to close and lock it. When properly closed, the holder should stay flush and will not open when the switch is turned upside down. The front (outer) slot is for a spare fuse.

⓶ Wiring the C13 Female Line Mains Plug 10A IEC is relatively simple: we wire it to the end of the main output cable coming off the emergency stop. As previously discussed, the emergency stop output main cable is connected to the main switch — the C13 female plug replaces the main switch.

After unbolting the C13 female plug and taking off the upper lid, I found three (3) screw terminals, with L, E and N printed next to the corresponding terminal slots. We need to use crimp ring connectors on each of the emergency stop output main cable’s Live, Earth and Neutral wires, then screw the wires onto the corresponding terminals.

Making these three connections can be quite fiddly. I found that the crimp ring connectors are a bit too long for this plug. I had to trim off the plastic ends of the connectors so that they could be fitted within the C13 casing. Once I had the unit on hand, I figured out how to do this. The photos below show the complete wiring of the emergency stop and the C13 plug:

💡 We should now have continuity on all three conductors from the AC plug end to the C13 plug end. Set the multimetre to Continuity. Place one probe on one of the AC inlet plug prongs (pins), and place the other probe on the corresponding C13 plug terminal. There should be continuity. Repeat the test for the other two conductors. If any of the conductors fails the continuity test, we should recheck the connection to ensure that there is proper electrical contact.

❸ Independent Tests

The final wiring arrangement looks like the image below:

💥 Do not connect the emergency stop to the AC main power inlet just yet.

💡 I installed a 6.3A fuse in the C14’s fuse holder as described. Plug the C13 mains plug into the C14 socket. We should now have continuity on all three conductors from the AC plug end to the corresponding C14 Earth Load, Neutral Load and Live Load wires. We should carry out continuity tests. If any of the conductors fails the test, we must fix it before going to the next step.

To independently test this wiring, I temporarily connected the C14’s Earth Load, Neutral Load and Live Load to a Female Cord Extension Socket, so that I could connect real appliances for testing.

🙏 We should now connect the emergency stop to the AC main power inlet.

I first tested it using my 15+ year-old Dremel; its plug has only two pins. The C14's switch and the emergency stop button behaved as expected.
I then tested it using my 30+ year-old Black & Decker drill; its plug is a three-pin plug. Again, the C14's switch and the emergency stop button behaved as expected.

It appears that the wiring is correct and that it works as intended. The next step is to connect it to the DIN rail blocks.

❹ Replacing the Main Switch and Fuse Holder

As mentioned at the outset, the C14 socket replaces the main switch and fuse holder. The change is simple: the C14’s Earth Load, Neutral Load and Live Load wires are connected to the corresponding DIN rail blocks in place of the main switch output wires. It was almost a drop-in replacement. This wiring update is illustrated in the diagram below:

I have made a steel bracket for the C14 socket. This is made from the same steel used for the 3-Pin 10A flush-mount mains socket bracket, as described. The photo below shows the C14 mounted in the bracket, which is bolted onto a wooden temporary stand using two M4 bolts:

The cut-out in this bracket is a touch too large. I might make another one if it proves to be insufficiently secure.

❺ I am quite happy with this change. Not having the bulky emergency stop and main switch permanently attached to the control box makes everything much more compact and portable.

The C14 fuse holder caught me out, I failed the Live conductor continuity test when at the final stage, since I installed the fuse into the spare slot, which means no fuse installed. This caused the fuse holder is not closed securely. I thought I have a faulty unit. But I remembered reading on another vendor website of a similar component that it has a slot for a spare fuse. It has been an interesting learning experience. I enjoy it.

The C14 fuse holder caught me out. I failed the Live conductor continuity test at the final stage because I had installed the fuse into the spare slot, which meant that no fuse was actually installed. This meant that the fuse holder could not be closed securely. I thought I had a faulty unit. But I remembered reading on another vendor’s website that a similar component had a slot for a spare fuse. It has been an interesting learning experience. I enjoy it.

Thank you for reading. I hope you find this record of my learning process helpful for your own setups. Take care and stay safe!

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Feature image source: