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wire construction question
dboyles Dec-21-01 08:23 PM
I'm wiring my parents' new house. The electrician dropped CAT5 to the bedrooms and it all comes together in the basement. The wires are bare, meaning I have to connect the jacks and the RJ-45 terminators.

Here's my question. Since premade cables (at least the ones I have) use a T568B configuration, I'd assume that's what I need to use. However, I can't get a signal after attaching the jack on one end of the cable and the terminator on the other. I'm using T568B on both ends, is this correct? Are there any common mistakes that novices make that I should look out for? I can handle the networking side of things fine, it's the wiring that I'm having trouble with.

P.S. As an experiment I took a short (1') length of cable and attached a jack on one end and a terminator on the other (again, both with T568B). Then I tried to put my 1' "extention" cable between my NIC and the premade cable coming out of my router. It didn't work, which is leading me to believe that the wiring isn't correct.

P.P.S. The jacks actually have "CAT 5e" on them, whereas I'm using CAT 5 cable. I was fairly confident that there are no compatibility issues, but I'm not certain. Could this be the problem?

Thanks in advance for any help.


3. RE: wire construction question
lbyard Dec-21-01 09:26 PM
In response to message 0
The same color code is used at the ends of a straight-thu cable, which is what you are trying to make and the configuration used to connect a PC to a hub or switch. Details on wiring are at http://duxcw.com/digest/Howto/network/cable/cable1.htm and in our Networking FAQs. I am working on an article on jacks (where have I heard that before? I really am, just don’t have a lot of time). By “terminator” I assume you mean plug. Or, do you mean a punch-down block? I use 568A and it is the preferred standard, but it doesn’t make any difference in the functioning of the cable. If, desired, the cables that are run in the walls in house can be one standard and the patch cables can be the other one. The first two pairs of the 586A standard are white-green and green. The background color is specified first. The first pair in the B standard consists of the white-orange and orange wires and in that order. The orange wire may have a white stripe or be solid. Wire one is the first one on the left when looking at the plug with the clip away and the end up. The second pair of wires used with 568A standard is the pair with white-orange and orange wires. They do not go to pins 3 AND 4. They go to pins 3 AND 6, respectively. The other wires/blue and brown pairs (and pins 4,5,7, and 8) are not used (are wasted) by the 100BASE-TX and 10BASE-T Ethernets, but do go into the plug as indicated here (http://duxcw.com/digest/Howto/network/cable/cable6.htm). The second pair in the 586B standard consists of the white-green and green wires… The pairs must not be untwisted more than ˝”. The jacks are wired according to the color code on the back of the jack where the wires are inserted. The apparent sequence of the connections at the back the jack may not be the same the pins they connect to at the front. Some wires are usually rerouted from one sequence at the back to the other at the front inside of the jack. Wiring them according to the code on the jack will produce the correct wiring at the other end of the jack where the plug plugs-in. Both color codes should be color-coded on the jack so it can be wired for either. I have seen commercially made cables that were labeled 586A and wired 586B. The runs in the wall should be with solid core cable, not stranded, which should not be longer than 10 feet (I have seen longer ones work). The patch cables are specified as stranded core, but solid core will work fine and that is what I use when not using commercially made patch cables. There are different kinds of RJ-45 plugs. Be sure you have the right kind of plug for the kind of wire used, solid or stranded core. Cat 5 and 5e plugs and jacks I have seen can be used interchangeably with CAT 5 and CAT 5e cable for 100Base-TX wiring. The most common mistakes are: the wrong sequence of wires (that’s #1), not trimming the wires properly so they are squared-off at ends and not getting them all the way into the plug (especially on the sides—inspect them before crimping), using the wrong kind of plugs, an improper crimp, untwisting the wires more than ˝”, nicked or broken wires (use a stripper to put a score in the outer jacket and then twist it off with your hands), improper (or no) testing, and drinking too much the night before (joke). Larry

4. RE: wire construction question
dboyles Dec-21-01 09:48 PM
In response to message 3
lbyard:

Thanks very much for the quick and thorough reply. Here's an update: I cut a 1' selecton of cable from a different spool (one that I bought last night). I put a male RJ-45 plug on one end (that is indeed what I meant by "terminator") and the aforementioned CAT 5e female plug on the other, both of them wired to the T568B standard. I put it in between my NIC and the router, and voila, it worked. Of course that was just the test, the real job is to use the bare wire that's already in the walls and get a signal. I had already tried in one room with no luck. I tried another with the same results. I installed a jack on a third wire and I got something: three blinking LEDs on my Linksys 16-port workgroup switch. I'm currently trying to figure out what that means, and I'm fearful that it means there is some sort of interference.

So that's my main fear now. This is a brand new house that's about a week away from being occupied, and I think all the CAT 5 in the walls might be bad (or routed improperly, such as near power cables). The fault lies equally with my parents (who didn't tell the electrician *exactly* what to do) and the electrician (who apparently didn't question why they wanted CAT 5). As an example he put RJ-11 wallplates and phone jacks on the end of the CAT 5 (you'd think the extra 4 wires would tip him off).

I'll post again when I solve the problem. Thanks again.


5. RE: wire construction question
lbyard Dec-21-01 10:07 PM
In response to message 4
And I'll bet he stapled them to the studs. I have seen this over and over again. Not all electricians know how to run network cable. I would certainly do it myself or hire someone who does network wiring as a primary part of their business and eye-ball it before letting them install the sheet rock. If they are not stapled, the old cables may be useful for pulling new ones. Pull some string with cable so additional cables can be installed in the future. If the cables are punched into a block, that could be where the problem is located. Larry

6. RE: wire construction question
dboyles Dec-22-01 01:28 AM
In response to message 5
And I'll bet he stapled them to the studs.

You guessed it. I believe the electrician has to do some more (unrelated) work at the house, hopefully I'll be here to instruct him in the ways of Ethernet. Since the wires are stapled to the studs, they may or may not be salvagable. If he can run new wire we'll do that, otherwise we'll probably go the wireless route (although I don't want to buy new NICs for all the machines and on top of that have to have a wired switch to support computers that don't have wireless NICs). Of course if he can and does drop new wire, i can get him to double up so I'll have two ports in each room.


7. RE: wire construction question
lbyard Dec-22-01 07:53 PM
In response to message 6
>they may or may not be salvagable.

Not. Stapling destroys the essential geometry of the cable and thus its transmission and noise immunity characterizes. Recommend spending the extra effort and time to rerun the cables. I would. Also, one cannot apply too much tension on the cable when pulling it. See http://duxcw.com/digest/Howto/network/cable/cable9.htm for cabling rules. Larry


8. RE: wire construction question
mjbearit Jan-07-02 09:14 PM
In response to message 4
To be fair to the electrician though, CAT 5 can be used (and is used quite widely commercially) for standard phone wiring. It gives you the extra line availability a lot of people need today. Unless he was specifically told that it was for a network, he would really have no way of knowing that. Honestly too, I would question an electrician about his experience with network cable installation before I turned him loose to install mine! Most of the "old-time" electrician types have little or no experience with todays network wiring needs.

9. RE: wire construction question
lbyard Jan-07-02 11:21 PM
In response to message 8
No. Correct is fair. My telephones are wired with CAT 5 cable. It is not stapled. I would not staple CAT 5 cable used for telephone wiring with an ordinary stapler or use staples that are pounded into studs for electric cable. Round voice grade/data cable (e.g., CAT 3, http://duxcw.com/faq/network/diffcat.htm) cable should not be stapled to studs and flattened. It is round for purpose. See http://duxcw.com/faq/network/cableclip.htm for more info. Larry

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