Wires in BT supplied ethernet cable

[Keith_Charlton]

Want to hard wire youview box. Means drilling through wall. Want small hole so just transmits cable so cut off adapter. Surprised to find only five shielded wires, not eight. Does anyone know the order these need to be cropped back into the ethernet plug?

[Keith_Beddoe]

@Keith_Charlton 

Welcome to this user forum for BT Retail phone and broadband customers.

What you have is the standard cable which BT supply, and is basically two pairs suitable for 100mbs. The other wire might be an unused ground connection.

There should be two distinct twisted pairs of a specific colour, so the easiest way would be to look at the plug at the other end of the cable, and wire it the same. Can you not look at the plug you cut off?

When I cut an Ethernet cable, I always leave a short cable on the cut end, and then simply re-join the two ends of the wire together, its a lot easier than trying to put a new plug on the end.

[Keith_Charlton]

Thankyou but my vision isn't great and even with a magnifying glass I can't makeout the colour order in the cut off plug. Also the wires are very fine and I wonder about feeding them back into a standard ethernet plug for crimping.

[Keith_Charlton]

They are blue, blue and white, orange, orange and white, and a naked copper wire.

[Keith_Beddoe]

So you cut off the plug without leaving any wires connected?

That makes it difficult.

The blue and the associated white will be one pair, and the orange and its white would be the other pair.

It does not actually matter if you cross the pairs, as most Ethernet port are auto detect.

I think its probably the standard 10 metre cable that is supplied, and I have a spare one in the loft comms area, so I will take a look, and then see if I can post a photo of the plug.

[Keith_Beddoe]

Unfortunately its not the same, as its a CAT5E cable with four pairs.

Maybe if another forum member has the same BT supplied one, they can look at the colours at the plug end?

[Keith_Beddoe]

I have found this picture on the BT Website. You can see the colours, but they do not seem to match what you have described, so you must have a different one.

[Keith_Charlton]

Thankyou for all your care. Those pictures are, however, more blurred than my vision. I think the order in my cable is orange/white,orange,blue/white,blank,blank,blue,blank,blank. There maybe a naked copper wire there but I can't see it.

[WSH · Accepted solution]

The older boxes are just a 100Mb/s interface and the supplied cable conformed to the old four wire 100Base-TX standard, (in my case, at least).

As Keith said, one of them is probably just an earth drain for the shielding.  That’s usually a bare wire.  The others will be pins 1, 2, 3 and 6.  That is numbered left to right with the pins in the plug facing you and the wires pointing downward.  It is wired ‘straight through’, i.e. 1 to 1, 2 to 2 etc. but also, as Keith said, that doesn’t usually matter today as the ports autosense whether it is straight through or crossover.

The colour of the plastic is largely irrelevant, (as the signal is colourblind).  A set order is only to make life easier for the next tech to work on it.  Unusual for it to be the orange and blue pairs.  It was usually the orange and green pairs.  So I would suggest orange/white, orange, blue/white, blue as pins 1, 2, 3 and 6 resp.  That complies as close as possible to the old standard.

Incidentally, a new 8 wire cat 5e cable will do fine as the other wires will just be ignored.

[Keith_Charlton]

That is exactly what I wanted to know. Thankyou so much.