Wiring a Wall Type RJ45 Jack

Jim Thompson · May 20, 2009

Wiring a Wall Type RJ45 Jack...

http://www.analog-innovations.com/SED/WallType_RJ45.jpg

for a pass-through into another room.

I presume I should use the "A" terminals, though I have not a clue,
I've never done anything but plug CAT-5 cables together before ;-)

Which is correct?

Thanks!

...Jim Thompson
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"When the government fears the People, that is Liberty.
When the People fear the Government, that is Tyranny."
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restrain the people, it is an instrument for the people to
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interests." - Patrick Henry

DJ Delorie · May 20, 2009

Jim Thompson said:
I presume I should use the "A" terminals, though I have not a clue,
I've never done anything but plug CAT-5 cables together before ;-)

Which is correct?

They're two different standards, both "correct". I use the B
configuration, which AFAIK is more reliable for higher speed ethernet.
Check your existing cables and see which they use.

http://en.wikipedia.org/wiki/TIA/EIA-568-B
http://en.wikipedia.org/wiki/Category_6_cable

I had one long cable that didn't work with the A wiring (packet loss),
but did work with the B wiring. YMMV.

Jim Thompson · May 20, 2009

They're two different standards, both "correct". I use the B
configuration, which AFAIK is more reliable for higher speed ethernet.
Check your existing cables and see which they use.

http://en.wikipedia.org/wiki/TIA/EIA-568-B
http://en.wikipedia.org/wiki/Category_6_cable

I had one long cable that didn't work with the A wiring (packet loss),
but did work with the B wiring. YMMV.

FatBytestard · May 20, 2009

Wiring a Wall Type RJ45 Jack...

http://www.analog-innovations.com/SED/WallType_RJ45.jpg

for a pass-through into another room.

I presume I should use the "A" terminals, though I have not a clue,
I've never done anything but plug CAT-5 cables together before ;-)

Which is correct?

Thanks!

...Jim Thompson

Buy a wall plate that has a jack on both sides, and wire like you are
used to wiring.

Jasen Betts · May 20, 2009

Wiring a Wall Type RJ45 Jack...

http://www.analog-innovations.com/SED/WallType_RJ45.jpg

for a pass-through into another room.

I presume I should use the "A" terminals, though I have not a clue,
I've never done anything but plug CAT-5 cables together before ;-)

T568A is the standard, you shouild use that unless you have a good reason
not to.

(electrically it doesn't matter so long as you are consistant about it.)

PeterD · May 20, 2009

They're two different standards, both "correct". I use the B
configuration, which AFAIK is more reliable for higher speed ethernet.

AFAIK, both are exactly the same electrically, only the polarity of
the wires (vis-a-vis color codes) is different. Were you to wire B to
B or A to A it is straight through. Wire A to B then it is a
cross-over.

Check your existing cables and see which they use.

http://en.wikipedia.org/wiki/TIA/EIA-568-B
http://en.wikipedia.org/wiki/Category_6_cable

I had one long cable that didn't work with the A wiring (packet loss),
but did work with the B wiring. YMMV.

Interesting... Actually as I think about this it may be possible, but
I'd suspect that there was a hidden flaw in the cable that changing
the wiring coincidentially fixed? Might that be possible?

DJ Delorie · May 20, 2009

PeterD said:
AFAIK, both are exactly the same electrically, only the polarity of
the wires (vis-a-vis color codes) is different. Were you to wire B to
B or A to A it is straight through. Wire A to B then it is a
cross-over.

Actually, not at all. Swapping green and orange swap whole pairs, not
swap wires within each pair.

I think the difference is in the number of twists per foot in the
green and orange pairs (orange has more). If the TPF match the blue
or brown pairs, you get more crosstalk, so using the correct pairs may
result in less crosstalk.

PeterD · May 20, 2009

Actually, not at all. Swapping green and orange swap whole pairs, not
swap wires within each pair.

I think the difference is in the number of twists per foot in the
green and orange pairs (orange has more). If the TPF match the blue
or brown pairs, you get more crosstalk, so using the correct pairs may
result in less crosstalk.

No question we have to do a full analysis of all factors! <bg>

I'm going to be doing a 200+ ft run in a month or so to the new
garage, and will try both ways and see if one is more reliable than
the other (I've got four cables run, only need one of them...)

FatBytestard · May 21, 2009

Actually, not at all. Swapping green and orange swap whole pairs, not
swap wires within each pair.

I think the difference is in the number of twists per foot in the
green and orange pairs (orange has more).

Absolutely not. ALL pairs are ALL made EXACTLY the same.

If the TPF match the blue
or brown pairs, you get more crosstalk, so using the correct pairs may
result in less crosstalk.

No. Wiring it wrong gets you half duplex operation (sometimes) AND
un-terminated lines exhibiting the stray signals that end up getting
referred to as cross-talk.

http://www.networkclue.com/hardware/network/termination.aspx

Also how well the terminations are made matter too.

If you have more than say a half inch of untwisted wires exposed at the
ends when you terminate, it will fail GbE tests, and you will get 100
base T or less performance.

Terminations should also be of the metallic shielded variety, as
opposed to the old plastic plug and crimpers method.

DJ Delorie · May 21, 2009

FatBytestard said:
Absolutely not. ALL pairs are ALL made EXACTLY the same.

I figured someone would say that, so I grabbed an orange pair and a
green pair off my work table and compared them before I posted to make
sure. I just re-checked, green is about 3.5 half-twists per inch,
orange is about 4.5. It's pretty consistent along the 2.5-foot
lengths I happened to have handy.

So no, all the pairs are not all exactly the same.

No. Wiring it wrong gets you half duplex operation (sometimes) AND
un-terminated lines exhibiting the stray signals that end up getting
referred to as cross-talk.

Only if you wire one end wrong. If you wire both ends the same wrong
way, you don't get the same type of problems.

http://www.networkclue.com/hardware/network/termination.aspx

That page disagrees with you:

"One thing that I have noticed though is that in CAT5e, the orange
and green pairs are twisted tighter than the blue and brown
pairs. So do not expect to get the CAT5e quality on the network drop
using the split pairs (brown and blue)."

In my case, blue 3.8 htpi, brown 2.8 htpi.

Clifford Heath · May 21, 2009

DJ said:
"One thing that I have noticed though is that in CAT5e, the orange
and green pairs are twisted tighter than the blue and brown
pairs. So do not expect to get the CAT5e quality on the network drop
using the split pairs (brown and blue)."

I guess that's to reduce cross-talk between pairs, at the expense of
lower immunity to external interference.

Ecnerwal · May 21, 2009

As far as I recall, without sacrificing any long chunks of cable to
check, which pairs are twisted more depends where you are in the cable -
they use "variable twist rate" (in at least some cat5e). A two-foot
sample would not show this.

Happily getting 1000 baseT with no errors from "old fashioned plastic".

Ecnerwal · May 21, 2009

I'm going to be doing a 200+ ft run in a month or so to the new
garage

You might want to pick up a set of ethernet surge suppressors. In any
case make sure that the grounding between the two buildings is good.

FatBytestard · May 21, 2009

I figured someone would say that, so I grabbed an orange pair and a
green pair off my work table and compared them before I posted to make
sure. I just re-checked, green is about 3.5 half-twists per inch,
orange is about 4.5. It's pretty consistent along the 2.5-foot
lengths I happened to have handy.

Jeez, dude, just go look up the friggin cat5e spec... and shutup.

The Internet is pretty goddamned handy.

Jim Thompson · May 21, 2009

[snip]

I'm going to be doing a 200+ ft run in a month or so to the new
garage, and will try both ways and see if one is more reliable than
the other (I've got four cables run, only need one of them...)

I'll second the recommendations for surge protection. Also watch out
for voltage differences between building grounds. I did such a run
for GenRad Portable Products Division (nee Omnicomp) in the mid '80's,
and observed about 15VAC between the two building "grounds" :-(

Ended up devising my own transformer drive/receive scheme.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice

Martin Riddle · May 21, 2009

PeterD said:
No question we have to do a full analysis of all factors! <bg>

I'm going to be doing a 200+ ft run in a month or so to the new
garage, and will try both ways and see if one is more reliable than
the other (I've got four cables run, only need one of them...)

Here is a LCOM link that would help on lighting protection.
http://www.l-com.com/productfamily.aspx?id=6385

Cheers

Archimedes' Lever · May 22, 2009

Here is a LCOM link that would help on lighting protection.
http://www.l-com.com/productfamily.aspx?id=6385

Cheers

Lighting protection?

Surge devices are not for "Lightning Protection" as a lightning stroke
would indeed make it all the way into your product if it hit.

Surge protection devices are just that. Protection from surges, and
only then, up to a certain point.

Martin Riddle · May 22, 2009

Archimedes' Lever said:
Lighting protection?

Surge devices are not for "Lightning Protection" as a lightning
stroke
would indeed make it all the way into your product if it hit.

Surge protection devices are just that. Protection from surges, and
only then, up to a certain point.

OK show me a lighting arrestor for Cat6(5e).

Archimedes' Lever · May 22, 2009

OK show me a lighting arrestor for Cat6(5e).

That is what I said. I said that there is NO SUCH THING.

Do you have reading issues?

Martin Riddle · May 22, 2009

Archimedes' Lever said:
That is what I said. I said that there is NO SUCH THING.

Do you have reading issues?

No reading issues here, it's just that you never stated that there is
'NO SUCH THING'.

Cheers

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Wiring a Wall Type RJ45 Jack

Wiring a Wall Type RJ45 Jack

Jim Thompson

DJ Delorie

Jim Thompson

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PeterD

DJ Delorie

PeterD

FatBytestard

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Clifford Heath

Ecnerwal

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