Confusing ethernet wiring problem

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casewindow

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#30059 27-Jan-2009 22:35

Our house is wired with Cat5 for phones.

Two of the ports have been converted to Ethernet jacks by an electrician.

This works fine - but now I want to expand on that with a third port. I know how to do this but I have found a problem with the original wiring (I think).

It was done like this:

Cat5 jack (T568B) -> cable run 1 -> individual clips -> cable run 2 -> Cat5 jack (T568B)

So what I did initiall was to replace the individual clips with two proper plugs & a simple pin-to-pin joiner from Dick Smith.
This works fine as it did before (real use + network LAN tester)

Cat5 jack (T568B) -> cable run 1 rj45 -> joiner - > rj45 cable run 2 -> Cat5 jack (T568B)

But when I try the network Lan tester on cable run 1 OR cable run 2 it says there is a short circuit??

How could the short circuits cancel each other out???

cyril7

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#192416 28-Jan-2009 07:53

Hi, no one short circuit will not cancel another. In the first circuit exactly what did you use to join them, (ie whats individual clips mean) can you give a reference/link of what was used or a picture, I suspect you will tell me scotch locs!.

And in the new run you are doing, exactly how have you done it, a picture purhaps.

Cyril

sbiddle

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#192418 28-Jan-2009 08:43

Just for the record you should be using T568A in New Zealand as it's AS/NZ standard for wiring.

If 568B has been used previously providing you stick with that and don't mix and match 568A and 568B it won't cause any issues but sticking with 568A for everything makes like simplier for anybody looking at the wiring in the future.

So your example 1 works OK with the connectors that you used? But 2 doesn't? When you crimped the RJ45's did you ensure you didn't wire these in reverse? Ie the colours do match up?

casewindow

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#192459 28-Jan-2009 12:23

I'll try post some pics when I get back

But the original work had each individual wire from the ends of each cable joined using a little plastic disc shaped thing (so eight of these in all).

This literally patched the two ends.

What I did was to cut these off, then take the wires (having checked the T568B wiring on the sockets) and created T658B plugs on each end.

Then I joined them with this: http://www.dse.co.nz/dse.shop/en/product/XH4232

So if I put the tester in the original sockets - then the signal shows as connected.

But if I take a plug that I've created out of the joiner and test just that side of the whole thing - I get a short - on either one.

I am starting to figure that maybe the length of the entire thing joined up means the short does not affect the tester?

So

tester->jack->cable 1->plug->joiner<-plug<-cable 2<-jack<-tester remote = works

tester->jack->cable 1->plug->tester remote=short
tester<-plug<-cable 2<-jack<-tester remote = short

I have wired up my own jack and plug and that equivalent of what fails above works. But if I plug this into either of above then I get a short. However I know the run for this second bit is shorter than either of the runs for the first two.

sbiddle

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#192464 28-Jan-2009 12:56

Based upon the two lines of your last post showing a short when you connect the jackpoint and RJ45 into the tester and get a short it would seem that either the RJ45 plug has been wired incorrectly.

What pairs do you get a short on? Does pair1 (pins 4/5 which are blue/blue white) and pair4 (pins 7/8 which are brown/brown white) have a short or do they pass OK?

casewindow

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#192507 28-Jan-2009 15:23

The tester I have does not seem to indicate where the short is - it simply has no lights lit up for the 8 wires but does have a red light against the SHORT indicator.

I have re-crimped the RJ45 plugs on each cable and still get the short.

I have also twice crimped the RJ45 plugs on the cable that does work and have never got a short.

there are three jacks and three plugs - three cat5 runs

One that I have wired both the jack and plug works with the tester

Both that had the jack wired previously and my wiring of the plug fails on each of the two runs individually

Connect both the bad ones together and they work

Connect the good one i did to either of the bad ones and it fails.

Infuriating and confusing.

cyril7

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#192509 28-Jan-2009 15:40

Where did you purchase the RJ45 plugs from, if DSE then they are for stranded cores not solid, and will cause both unreliable connections and sometimes shorts. Might I suggest you try something like this, you can purchase these from most electrical suppliers such as Corys, Mastetrade or Russels, although they may need to order them in for you, otherwise PM me and I can supply a couple.

Cyril

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Shop now on Samsung phones, tablets, TVs and more (affiliate link).

casewindow

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#192686 29-Jan-2009 10:40

Yes I did get the plugs from DSE....

I'll have a look into solid core ones and report back

casewindow

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#193025 31-Jan-2009 01:25

It still does not work unfortunately.

I didn't get the punch block joiner thing you pasted but did get some "solid core" RJ45 plugs from Corys. They seem to have different prongs in the ends when compared to the DSE ones.

None-the-less I still get the intermittent shorts on different wires.

The only thing that seems to work is the original two runs of Cat5 together, with either the DSE or Corys RJ45s and the DSE joiner.

What a PITA. I'm going to leave it for a while and then look again at a later date to do it with one of those blocks.