[CLUE-Tech] ethernet wiring

[Dave Anselmi]

Jeremiah Stanley wrote:

> Am I to believe that I can run two sets of ethernet (two plugs) off of the
> same cable (or is that a bad idea)? I suppose I could also run the phone
> line on the same cable as well...

Yes, you could.  You might get more crosstalk that way, but since the cable is
designed to handle duplex data, quadruplex shouldn't be significantly
different.  Especially if you use CAT 5E that can handle gigabit ethernet and
you only run it at 100Mbps.

This may not be as useful as it sounds.  Both jacks, at both ends, have to be
in the same place.  You will also wind up wiring two pairs (blue and brown,
normally unused) into different colors at the jack (orange and green) and you
will have to be consistent at both ends.  That introduces more chance of
error, and confusion at a later date when you've forgotten how you did it.
I've seen full time installers mess up a standard install, so you'll have to
be extra careful (which is hard if you're doing a lot of jacks).

Finally, the web page Tim mentioned covers this some.  It also notes that
normally the blue pair is used for telephones.  So if blue is unused in
ethernet, you won't accidentally get your NIC exposed to phone voltage (which
may be as high as 50v).  But as I recall, in a two line phone, the orange pair
is line 2, so you're out of luck in that case.

In the end, you can do it however you like.  But if you don't do something
'standard' you're best to document heavily.  And don't be pennywise and pound
foolish.  Adding a second jack to a single cable may save you $15-20 on a
100ft run.  But your first hour of troubleshooting when it doesn't work (or
extra hour of being careful on the install) will burn most of your savings.

Dave