My very own flexible 25M extension cable, single socket with an IP66 protection rating
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Safety Disclaimer: This article isn’t intended as a DIY guide, I recommend using professional services or purchasing products directly always rather than making yourself. I take no responsibility for any injuries that occur. I write this article merely to document the things I do for money saving, or for ideas. All devices that I use electrically will be protected by a plug in circuit breaker for extra protection
Why create one and not buy one?
Well, obviously theres no fun in just buying something, and this website is about DIY and money saving. Learning a skill means you have that skill for life. There are plenty of people who don’t even know how to wire plugs.
Making my own cables, allow me to customise them. The problem with purchasing a pre-made kit, other than it being expensive, is that it doesn’t have the exact requirements I wanted. I can find a long extension which is either 50m – 4 gang, or something like 25m – 2 gang.
I simply wanted a 1 gang extension. I also wanted something loose rather than on a wind up reel, as I find it easier to loop them quickly when needed. I purchased a 50 Metre reel of Electrical cable. I could make a variety of extension cables with the relevant socket housings just by cutting the able to length. I only wanted long cables for working on my car from the shed. So chopped the reel in half for two long cables to use.
I “generally” have no need for using extension cables, however for the times when I want to run a cable to my car. Or having a long cable, I don’t want to be joining them together or unravelling a long reel. I’d rather have something that I can quickly grab when I need it.
Does it work?
Yes, obviously. First thing I did was to plug it in and hook up a fan to make sure there was no problems.
Technical Considerations when making your own extension
This isn’t really a section I’m knowlegeable about. However I understand most of the technicalities surrounding them. All cables have resistance in them, and generally if a cable is wound it has more resistance (this is why you are meant to unwind reels), otherwise it messes up their resistance and affects power carrying capacity (resistance in wire = heat). The more heat it carries the less it performs. I’m using my extension cable in a “free air” style setup, so there’s plenty of room for heat to escape.
Amp rating and Voltage drop were the main factors that I had to consider when making my Electrical cable
A flex cable that is 1.5mm2 in diameter across the conductors can carry a varying amount of power based on it’s fixings and the temperature of the cable. Generally speaking though, a cable this size is rated for 10A of ampacity, based on UK power that means I could power something up to 2300w in power which is fine for me. In terms of voltage drop the length of the cables I’m making (around 25m) have a voltage drop of around 30mV per meter. So I’d be losing around 7.5v in power supply over the full distance of the cable.
So the realistic power is now 10A x 222.5v (2250w) which isn’t worth worrying about. As I mainly intend to use things like a Drill, Henry Hoover, and Pressure Washer (all around 1300w) at most I’m going to be using 6-7A of power which is fine for the cable exntesion that I need and it is sufficiently sized for my requirements.
What are the standard wiring colours on modern cable?
There are 3 colours on Electrical cable of modern cables. In terms of wiring, there’s a simple method to remember for wiring sockets:
- Live – The Live wire is brown in colour – The second letter of the Brown wire is R, this goes to the right
- Earth – The Earth wire is Green/Yellow in colour – The spare wire is Earth and goes above
- Neutral – The Neutral wire is Blue in colour – The second letter of the Blue wire is L, this goes to the left
What items do you need for making your own cables?
I purchased all the things I needed from Toolstation in the UK, I paid the following for the items
- 2 x 13A Plugs £1.05 each (code 74540)
- 2 x IP66 Housing £9.99 each (code 36199)
- Doncaster Cables 1.5mm2 cable 50M reel £40.00 (code 13309)
The total cost was £62.08 which breaks down to (£31.04 per 25m cable)
How I made my IP66 13A Single Socket extension
First I needed a couple of 13A plugs for each individual extension cable that I will be making
My bundle of cable. I purchased a 50M reel so that I could chop it in half and make 2 x 25 Metre extension reels. This was the 1.5mm cables, this cable is rated up to 10A (in a worst case scenario)
I unravelled the entire reel then chopped it in half so that I could make a couple of cables, over time after use this should get more flexible so I can loop it better. It’s been coiled up, so at the moment looks like crap.
I found the end of the cable (eventually), onwards with removing the insulation jacket exposing the 3 cores
I stripped the ends of the cable, after removing the outer sheath. The plugs come with instructions so you know how much to remove off them
After stripping the wires on the cable, they need securing into the housing. This wasn’t my best effort with wiring a plug. It’s been a while since I did one myself, and forgot the techniques I used. When I did the second plug it was much nicer. Seperate the plug by undoing the screws on the rear. Then I put the cable under the plastic clamp to secure it. Making the connections I then simply pushed each connector up for better access, I stripped the wires and screwed them in. Then reassembled the faceplate of the 13A plug.
I pushed out the plug covering the cable gland socket to feed the cable through
The cable was fed through the hole that I made. I used a grommet just for now, but eventually I’ll remove the wires from the back panel, and replace this with a strain relief gland, or a water proof plug on the cable for strain relief and protection from the elements. The IP66 box I have isn’t meant to be used in this manner, as it’s meant for mounting somewhere, so there’s actually a bit of weight to it. As such I wanted to create a bit of strain relief, maybe I’ll loop the cable and ziptie it so that there is a bit of protection when picking it up loosely as to not damage the internal connections.
Repeating the process on the other end of the cable for the IP66 single socket, I stripped the cables
The IP66 housings from British General. These are actually nicely well made, they have silical gel in them when shipped to keep out moisture. A firm locking and release mechanism, easy to disassemble, and accessible points for all the glands with multiple options for removal. Very well pleased with them
After stripping the other end of the cable, and the ends of the other side. I loosened the screws on the back of the switch plate, and then hooked them up. Making sure connections were firm and passed the tug test. I didn’t actually picture this, when you remove the top cover of the box to access the underneath. You can actually dismantle the front panel entirely by loosing 4 screws on silver metallic clamps, giving you even more access.
I also decided to wire up the extra Earth terminal on the back of the housing to the casing itself. This isn’t really needed unless you’re using metal conduit, but I was in the back and it adds an extra Earth point for safety so no issue.
After I wired up the panel, and positioned it how I wanted it. I replaced the cover then turned the locking connectors to secure the front in place and retain the IP66 rating. The cover is removable when it’s first received, and has an O-ring behind the housing to help keep water and dust out.
The housing assembled with the cable installed
Testing the switch after assembly to verify it has been assembled and working correctly. I plugged in a fan to verify it was working. The power light came on and no fuses blew, so no bad wiring on the switch and nothing wired up incorrectly
What other things do you need to consider?
One of the points I considered when making my extension cables, was the positioning of the entry for the cable. I didn’t like the idea of cable entry on the same side of the IP66 box as the cable coming out of it. I just thought it would be bulky and in the way. I preferred the idea of the cable going into the top section, and the cable that’s plugged into comes out the other side. That way it’s symmetrical and doesn’t iunterfere with anything.
The benefit of the box is that you can customise the entry points with the removable glands however you want, so it’s really down to preference and rotate as you see fit. Although obviously the cable still needs to be able to come out the bottom, so it’s better to position your entry cable, than repositioning the switch.
Resources you may find useful
Some of these sites may prove useful for research and giving you the information you need. Again this article is simply for my own projects, I just like to document them and always recommend using a professional. You don’t want a cable at its limit, it’s better to have a thicker cable when running to more power limits, as it reduces it’s rating when the cable is hotter and more chance of accidents.
As a safe limit, I’d recommend going to the next cable size up if you are going to be using more than 50% of the maximum cable rating
- Southwire Voltage drop calculator – Useful for working out maximum distance of wire for what power you need
- MM2 to AWG Amp Ratings – A quick visible table for maximum amps
- AWG to MM2 Wire size converter – Most voltage drops give you the details based on AWG wire sizes rather than MM2
- As a note on 3 of the more common sizes as there isn’t an exact AWG size for UK wires
- 0.75mm2 is around AWG19 ~ 6A maximum
- 1.0mm2 is around AWG17 ~9A maximum
- 1.5mm2 is around AWG15 ~13A maximum
- As a note on 3 of the more common sizes as there isn’t an exact AWG size for UK wires
Thanks for reading.
