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Master Socket 5C MK4 wiring

Rooster295
Investigator
Investigator

‎04-05-2025 04:29 PM

Hello,

I have recently ently moved into a small property and have passed the EE activation date for my property. I am FTTC. 

 

However, I have been having issues with set up and two engineer visits to the cabinet and to make sure I set things up right have not solved anything. Personally, I believe there is a problem with the Master Socket Wiring. 

Everywhere I see talking about Master cable wires talks about blue, white orange etc. I have Red, Blue, Green and Brown. I have looked at the back and it is currently set up for Blue in A and Red in B, is this correct?

0 Helpful
20 REPLIES 20
Profile closed
Not applicable

‎05-05-2025 03:54 PM

You may find this site useful:

https://telephonesuk.org.uk/wiring-info/

I'm not a telecoms engineer, (just an IT tech) but, as has been said, my understanding is that modern equipment isn’t polarity sensitive, so the A & B could be either way round.  (Very old equipment is, mind you).  My incoming line is clearly CW1406 with the orange and white pair connected, in a house built in 1990.

Couple of things:  1) FTTC will work, (but badly), on one wire.  If your speeds are through the floor, it could be a bad connection on one of the wires.  2) The most likely culprit for problems is that Mk4 filter.  (Their reputation wasn’t terribly good).  Plugging straight into the test socket behind it should eliminate any problems if that’s the case.