Wiring help?

Mike McCarty Mike.McCarty at sbcglobal.net
Wed Apr 5 21:10:47 UTC 2006


Tim wrote:
> Tim:
> 
>>>I wonder if the way some cables are formed makes it easier to wire it
>>>one way or another?  Hand wrangling the wires into the right place to
> 
> 
> Mike McCarty:
> 
>>The differences between the two standards has nothing to do with
>>how the wires are connected, it has to do with which colors of
>>wires go into which holes. Electrically, they are identical.
> 
> I know that, but I was thinking of this situation:  If you've ever tried
> to wire up multi-pin connectors, a lot, you notice that some cables are
> formed with the wires spread so that they align with the pins.  You'll
> find it easy to put a plug on one end and a socket on another, because
> everything is already in the right place.  But try putting the plugs on
> the other ends, and you have to cross wires over each other.  Even
> three-core mains cables are like that, it's actually forbidden to put
> them on the wrong end, because you'll cross active over the (stupidly
> named) neutral, and if they chafe, they'll short together.

Oh, I see what you mean, now. I wasn't aware of the specific issue
of power wiring, not having done much of that. On many cables the
wires are color coded like resistors or capacitors, and nicely
made to fit the connector, yes. Some of them are molded so that
you cut one flat or the other in order to get the order you need
without having to add an additional twist to the pairs. But I've
only seen this with twisted pair ribbon cable, not CAT5.

No, the difference is historical, and related to the colors
specified for the pair numbers. I've figured it out, now.
It really makes no difference for the *cable*, but it's the
*jack* that is important. But it is also important (not
electrically) to maintain the same colors all the way through
so when someone comes along and wants to do test, he doesn't
get confused because Pair 1 is on the "wrong" colored wires,
and what he thinks is Pair 1 really has no connection at the
jack on the other end of the cable.

Mike
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