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Modernizing old house network wiring - Part 3 - CAT5 Analysis

It's another day, and now it's time to analyze the CAT5 wiring.

Last time I disconnected all the house wiring from the telephone company.  I removed all the old telephone-style RJ11 jacks.  And then I crimped new RJ45 connectors onto the cables using the 568B standard.

The Plan

Now I plan to identify and test each cable.  Which cable in the basement is connected to which specific wall jack?  Does that cable look healthy, with all 8 conductors properly working?  All of this requires a simple tester and running around the building.

Getting the right Ethernet cable tester.

A tester is important because it makes it really easy to check the basic health of a cable.  I have a very cheap tester, so it only does the most basic continuity test of a traditional cable with traditional "RJ" connectors.  My tester can't identify what exactly is wrong... it's basically "looks OK" or "something's not right", and it leaves it to me to figure out exactly what's not right.

But it was inexpensive.  Like under $10 inexpensive.  So I don't feel too bad because it does the job and I hope not to find too much bad stuff.  Ha.  Maybe in the future I'll buy a slightly better tester.

Outlet Identification and Testing Process

Now that I have an RJ45 connector exposed at each jack, and a RJ45 connector for each cable at the "telecom center" in my basement, it should be easy to test.

I will plug in the "small unit" of the tester into a cable in the basement, and then I'll run around the building to each outlet and plug in the "big end" of the tester.  Once any lights appear on the tester, I'll know which basement cable connects to that outlet.   If less than all of the 8 little lights glow, I'll know that there is something weird going on with that cable.

Hopefully, using this process I'll be able to quickly identify which cable in the basement goes to which jack, and I'll be able to assess the health of each cable.

Marking the cables

This is the easy part.  I'll use my trusty Brother label maker to put an identifier on each of the cables in the basement, such as "Living Rm East" or "Kitchen" or whatever.  I'll make a note if any of the cables show if fewer than 8 conductors are connected.

Cable Testing

OK, I did it all.   I plugged the small test unit into one of the cables in the basement and started to run around to all the jacks in the house.  The first jack, in the finished part of the basement, had all 8 lights glowing.  Success!   I labelled the cable "Basement East".  Then I repeated the testing process for each cable and jack.

Well, not all was perfect.  Here's what I found:

  1. Basement East = good
  2. Den South = good
  3. Living Room = good
  4. Den North = good
  5. Kitchen = conductor 8 seems bad
  6. Bedroom 1, Bedroom 2, Master Bed = only conductor 5 works???

OK, clearly some is good!  Yay!  That's far better than nothing.  But the kitchen is a little broken, and the upstairs bedrooms are very weird.  Time to dig into that!

Analysis of the Broken & Miswired

Kitchen - conductor 8 is not working.

My tester, despite its weaknesses, shows that the 8th conductor is not working.  That could be due one of the connectors, or a break inside the cable itself.   I visually inspected the connectors and they look great to me, and so I'll need to look at this cable a little more closely.

But there is good news, the first being is that if this cable is bad, it'll be very easy to replace.  The kitchen is almost immediately above the telecom panel in the basement.  Ripping out and replacing this single cable would be very easy.

But there is even better news.  I have no plans to plug a device into the kitchen.  Furthermore, plain old 100Mbit ethernet doesn't even use the number 8 conductor. 

So I just marked the cable with "Bad #8", so I won't forget, and move onto solving important problems.

Bedrooms - All bad

All the bedrooms seem to connect to a single cable in the basement.  Furthermore, my tester is showing that only conductor 5 is working.  This is completely weird, because at least two conductors are required to make a circuit.  But whatever: none of the bedroom cables are ready for Ethernet.

To me, it looks like a single Cat5 cable runs from the basement to the attic, and from there there are some splices to distribute the old telecom pairs to each of the rooms.

Next Time...

Next time, I hope to get into the attic and see if I can find any of this cabling and any junction boxes, and make it sane.

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