I was wondering what the maximum cable length is for an RJ45 Cat5 cable. What might happen if a person exceeds the recomended length?

Thanks

Depends on what you're using it for. If it's ethernet, I believe you're restricted to 100m, or about 382ft, if I remember right.

Iolair MacWalter
Network Engineer

90 meters for the horizontal portion and 10 meters for patch / station cables.  Equals 328' not sure if that is a typo above.  Like iolair says it depends what you are using it for... if you are running analog voice the distance is much further than if you are trying to run 100mb ethernet.  

Let the cat5 and RJ45 semantics begin...

"However beautiful the strategy, you should occasionally look at the results." Sir Winston Churchill

Exceed the length and you probably start getting retries because the packets don't come through correctly. At worst case you'll try copying something or printing something and everything starts to work but it never finishes. Or you never see the box on the other end.

If you are marginal, it helps if both ends have the same NIC.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

edfair is on the right track, depends on how much you exceed and the attenuation, but basically what would happen is...
Say you are sending a document to the printer, once sent the computer waits for confirmation that it was printed, ever see the little box popup that says your document did not print?
If it does not receive the response in the required time, it will resend, if you have enough computers all experiencing this problem and you can flood and crash the network.
Mind you this is the theoretical case, but this is why you have distance limitations.
If you are talking about video over Cat 5, there are products on the market that can go 1,000', so again, depends on the application.
 

Richard S. Anderson, RCDD
http://www.servamatic.net

BTW The Horizontal Link can be 90 meters = 295"
The channel is 100 meters = 328'

Richard S. Anderson, RCDD
http://www.servamatic.net

Just as an FYI
There is alot of headend built into the jack's and cable that allow for extra length or bad terminations poor cable pulling practises etc etc.

I have installed a few cables that went well over the recommend lenght and worked fine. did several at 375 because the customer just flat out refused to allow another point of connection wanted everything in one closet.
but make sure that you understand there is no way to certify or know that it will work properly.
I just got lucky but I dont recomend anyone trying to go over the lenght with out knowing the risk.

Thanks for catching my typo - yes, 328' is correct.

Iolair MacWalter
Network Engineer

  I would have to agree with what is said anything over 100 meters can be "iffy"  it really depends, I have had one cable run at 425 feet, had to dumb down the NIC to 10mb half duplex to get it to work but it worked, took about 5-10 minutes (literally)to Login to the network, every once in a while I run into werid stuff like that, helps to have cable IQ to check distances,  

Play it safe and stick with 328 feet.  If you exceed it then you never know what might happen, corrupt data, slow response times, added network congestion, etc.

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