How many conductors does Ethernet require.

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Nooooooo........ Never install Cat3 in a structured wiring system. If 'spose if you terminate the Cat3 on a RJ6 so it can only be used for phones then that would be OK, I guess, but not on a RJ45.
 
dbuckley said:
Nooooooo........ Never install Cat3 in a structured wiring system. If 'spose if you terminate the Cat3 on a RJ6 so it can only be used for phones then that would be OK, I guess, but not on a RJ45.
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POTS doesn't require more than CAT-3, even with DSL. Plus, almost all phone systems now use single pairs for multiple lines; the switching is done in the CPU.

I would never suggest mixing CAT ratings. I meant to use the CAT-3 for RJ-11 (not 6) jacks.

Few locations in networks require more than a single drop, and I'm not a fan of the run-everything-to-every-location way of doing things. Most installs have a plan.
 
LarryFine said:
Few locations in networks require more than a single drop, and I'm not a fan of the run-everything-to-every-location way of doing things. Most installs have a plan.
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I get the impression your thinking houses and dbuckley is thinking commercial.

Where I am at almost all locations will get 3 to 4 Cat-5e or whatever is popular now, one will be used for phone and the remainders for data. Now I have yet to see a need for each persons cubicle to get 3 data runs when only one half of one cable will end up used but work is work.

I have not seen Cat 3 used in commercial in this area for at least 10 years even though it would work fine for phones, I believe some here also like how it is easier to terminate.
 
iwire said:
I get the impression your thinking houses and dbuckley is thinking commercial.
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Well, both, really, having done both.

I have not seen Cat 3 used in commercial in this area for at least 10 years even though it would work fine for phones, I believe some here also like how it is easier to terminate.
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And not get mixed up with the CAT-5.
 
i wouldnt install any cat3 in commercial environments since everything is moving toward IP phones (not talking about vonage, i mean IP-PBX from avaya, nortel, cisco, and others)
 
danickstr said:
I will second the case against running POTS and TCP/IP on the same cable. Even though it can be done (if you rig it) it is a potential source of problems.

While only 2 pairs are used for TCP/IP, they are very sensitive to the fat voltage impedance from a ringing phone, which as most of us know, will make you jump if you are holding them leads and the phone rings:)

But you will not improve the speed of TCP/IP to my knowledge by connecting the unused pairs, although some may consider it good practice to do, in the event of future spec changes, or to use pair one (4-5) if they decide to change the cable to POTS. But hooking up 7-8 is almost always just extra work.
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Some wiring system warranties require certification of the premise wiring. This is usually referred to as an end-to-end warranty. You can't certify to Cat5, Cat5e, or Cat6 standards without 7&8 being terminated. I have also been told, though not been able to verify, that some network switch manufacturers will not support performance issues if the wiring is not certified.
 
iwire said:
OK I know Cat 5, Cat 5E, Cat 6 etc all contain 4 pairs (8 conductors) but how many can I make it work with?

I have a situation with a customer that is running a phone on one pair leaving 3 pairs for the PC. Now it appears one pair is open.

Can I make it work on just two pairs?

This is not subject to any testing or certification, all they care about is getting it to work. I suggested wireless but they do not want to go that way.
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Another option is to use a module by ONQ/Legrand to split the Data/Phone on a single CAT5E.
http://www.onqlegrand.com/products/CO1000
I've used these several times on an existing installation.
 
Something else to consider is that certain POE hardware, most notably Motorola Canopy systems, use all 4 pairs for the ethernet signal, power, grounding and sync signals.

Depending upon where the POE equipment is, and how the cable is ran, you may lose the extra pairs.
 
don_resqcapt19 said:
POE also uses the two spare pairs to provide power to network devices along with the Ethernet signal.
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Depends on which alternative of the PoE spec is in use. So-called "midspan" devices do in fact use the two spare pairs to supply <=48VDC

"Endspan" devices use phantom power over the data pairs to supply <=48VDC

The Power Sourcing Equipment determines whether Alternative A or Alternative B is used. All 802.3af-compliant Powered Devices must be able to accept power via either method.

This page has a nice diagram.

More recently they've introduced "High-Power" PoE which uses both methods simultaneously to double the current capacity.

Learned this the hard way when a Netgear PoE switch (endspan) was replaced with a Dell PoE switch (a rare model that implements midspan even though it's not) None of the attached Powered Devices would work. Turns out all the CAT5 runs were split to two jacks each (Jack 1 Or+Gr, Jack 2 Bl+Br) Had to add a second run to each location and terminate everything normally.

PowerDSine makes a cool little plug-in PoE tester that checks for the presence of either method.
 
Rick,
Thanks....I was not aware of putting the power on the data pairs. The few I have worked with used the spare pairs for the power.

PS: The company in the diagram you linked to has there main office in the town I live in.
 
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