For times when an off-the-shelf patch lead isn’t long enough, knowing how to terminate
network cables with an RJ45 plug is a useful skill to have.
So, to start making your own ethernet cables you will need...
from snapping
An RJ45 crimping tool
A pair of snips
And one of these mini wire stripper and punch down tools is useful to own and will also
be useful if you want to wire up any wall sockets as well
Finally, a Cable tester - this is essential to verify the cable and all 8 connections
are correct and working before you go to use it in your network setup.
I’ve left affiliate links in the video description for all these items.
So, take your wire cutters and cut however much cable you need for the cable run you’re
working on - being sure to leave a generous amount of excess, partly because a few centimetres
will get chopped from either end, and because it’s always better to have a little bit
of excess rather than realise the cable’s too short! Some crimping tools also include
a cutter and a stripper, although I tend to use my own separate wire cutters and strippers
- but it’s up to you.
If you’re going to be putting strain relief boots on, slide one on now before you proceed
to start putting the end on.
Network cable consists of 4 twisted pairs, so 8 wires in total. Cat6 cable usually also
has a loose plastic core running down the centre, to reduce crosstalk between those
4 twisted pairs. Each pair is colour-coded, with one of the pair being a solid colour
and the other is a tribute act to an American rock duo from Detroit.
Strip off about a 3cm length of the outer jacket, being careful not to damage the conductors
inside.
Snip off the plastic crosstalk separator and the ripcord thread that both run along inside
the cable. Then untwist all 4 pairs of wires, and pinch each wire tightly between your thumb
and forefinger and run along like this to straighten them all out as best you can.
You can use the bit of jacket that you’ve just stripped off to help untwist the pairs
if you like, by sliding it down between them like this. Many people prefer doing it this
way, as it’s a bit easier on your fingers!
Next, it’s time to arrange the 8 wires in the correct order so that we can feed them
into the plug. I keep this little printout in my tub of connectors, or you can just Google
“RJ45 wiring diagram”. There are 2 main standards, T-568A and T-568B - the only difference
is the greens and the oranges trade places. The key importance is that the wiring is the
same on both ends of the cable, so if you’re just making a length of cable for yourself
at home and terminating both ends with an RJ45 plug then it really doesn’t make any
difference - as long as you use the same both end. I tend to use T-568B because it’s the
most widely used. So that’s orange and white, solid orange, green and white, solid blue,
blue and white, solid green, brown and white, solid brown.
If you’re adding cabling to an existing setup, or replacing a faulty end, then make
sure you use whatever standard is already in use at the location, to make things easier
for yourself and any other engineers who might do work there after you.
So, arrange them in the right order and again, run your fingers along to help straighten
them out even more so that they sit right and in the correct position. I find it helpful
at this point to take my wire cutters and gently grip the cables - but don’t snip
them just yet - and to bunch the ends right up to each other and double check the colours
are still in the correct order.
Then, take an RJ45 plug and hold it up against the end of your cable, and line the end of
the outer jacket up with the point that it’ll end up at inside the plug. The key here is
that we want all 8 wires inside the plug to be long enough to reach right to the very
end, but not so long that the outer jacket isn’t gripped securely when we crimp it
in a moment.
Then slide your snips down the wires, keeping them bunched together and in the right order,
and come to rest in line with the very tip of the RJ45 plug. Put the plug down for a
moment and hold the wires really tightly between your thumb and forefinger as you snip the
excess off, so they stay bunched together and in the right order. Then, being careful
not to let them come loose, slide them up and into the plug with the clip end facing
away from you. Make sure you push it all the way to the pins at the end and so that the
outer jacket is fully inside ready to be gripped when you crimp.
Visually inspect the colours to make sure they’re still in the right order, and then
use the crimping tool to finish the job. This does two things: it splices all 8 wires into
the copper pins at the end there and it bends the gripper to hold the entire cable securely
inside the plug.
You can then slide the strain relief boot up and over the clip and that’s the first
end done! Repeat exactly the same process with the same wiring order for the other end,
and then be sure to test the cable with a cable tester like this.
This checks all 8 wires individually - it will tell you that the 8 connections are good
on both ends and also that it’s wired up correctly on both ends in the right order
- or at least the same order both ends. It does this by sending a pulse down each wire
in turn, from the Master to the Remote. You should see the sequence going from 1 to 8
on both ends, and when it does you know that the cable is working perfectly. If you get
a sequence like this then you know you’ve made a mistake somewhere. If it’s
a long cable run - and both Cat5e and Cat6 cable are good for 100m - then you can separate
the Master and Remote parts of the cable tester and put one at each end of the cable run to
test it.
Sometimes, rather than an RJ45 plug you’ll want to terminate the network cable to a keystone
jack in a wall socket, like this one. Click the video on-screen now to learn how to do
that.