Any uses for cat3

[dereckbc]

Another law....you can't use your megger for fishing!

A Cajun fisherman named Thibodeaux pulls into the dock and has a boat full of fish. The Game Ranger happens to be around and ask: ?Thibodeaux what is your secret?? Thibodeaux replies: ?hop in and I will show you:.

They go to a remote secret spot on the bayou and Thibodeaux pulls out a stick of dynamite, lights the fuse, throws it in the water, and KABOOM fish float to the surface which Thibodeaux starts to pick up with a net.

The Game Ranger says to Thibodeaux, ?That is illegal and I am going to have to fine you?.

Thibodeaux, shakes his head, lights another stick of dynamite, hands it to the Ranger, and says: ?Are you going to fish or talk all day??

 

[mdshunk]

Another law....you can't use your megger for fishing!

I guess I'm just astounded that there is a Federal law that has a min wire type spec. Seems odd to me that a building served with old pulp cable or C-rural wire would need at least cat3.

 

[Rampage_Rick]

cat3 is fine for voice circuits. I see alot of commercial LV contractors still using cat3 for voice since its a little more compact and they can cram a few more in the conduit. Its also faster to work with when terminating it at blocks since the pairs dont have to be untwisted like cat5
...
Cat5E is all that is needed for data. Cat6 is useless, and i cant figure out why they even make the stuff. There is NO data standard which requires cat6 and the stuff is a pain to work with. gigabit specs CAT5E, and 10-gig over copper requires CAT6-A which is a whole different beast than Cat6.

What you say about CAT3 is true, but there's no upgrade path. If you install CAT3 the only thing it can ever be used for is voice or 10Base-T

CAT5e does darn near everything, and the sheer demand for it make it economically viable. I pull it everywhere for everything: Voice, data, video... The only difference is the jacket color. Even the local telco has been pulling CAT5e for their residential drops for the past few years, in anticipation of rolling out Fiber To The Curb.

While it's true that you can get gigabit to work over CAT5e, the actual 1000Base-T spec is for 4 bidirectional 250MHz channels. CAT5e is only spec'd to 100MHz, though many manufacturers do go higher. Cables can be tested up to any frequency that is supported by the test equipment, but such measurements are meaningless without the context of applications and cabling standards. Bandwidth is defined as the highest frequency up to which positive power sum ACR (Attenuation to Crosstalk Ratio) is greater than zero. I have in my hand some cable that's marked "Draft 5e" and tested to 350MHz. Should be good for 1.4 gigabit, no?

[B][U]SPEC[/U]  [U]Tested to[/U]    [U]Notes[/U][/B]
CAT3     16MHz     still recognized by TIA/EIA-568-B
CAT5    100MHz     no longer recognized by TIA/EIA-568-B
CAT5e   100MHz     adds specs for Far End Crosstalk
CAT6    250MHz     11dB improvement in NEXT at connectors, meets more stringent Class B EMC requirements
CAT6a   550MHz     adds specs for Alien Crosstalk (from neighboring cables)
CAT7    600MHz     specs four individually-shielded pairs inside an overall shield
CAT7a  1000MHz     Will convey full bandwidth HD video and possibly the next advance in Ethernet after 10Gigabit

Everything before CAT7 is Unshielded Twisted Pair. In all likelihood CAT6a will be backward compatible with the existing standards while the CAT7 cable will be bulkier and require different interfaces. Initially, the default CAT7 connector was RJ45, but now the TERA connector has been chosen as the official connector and is described in IEC 61076-3-104. CAT7 cabling with TERA connectors is the only copper cabling solution in the world to pass US Department of Defence TEMPEST ?overhearing' tests. Look for it at your local Wally World beginning in 2013

 

[tom baker]

Cat 3 is good for alarm wiring.

 

[Minuteman]

Cat 3 is good for alarm wiring.

And for strapping ladders to the van.

 

[mdshunk]

Cat 3 is good for alarm wiring.

...and a lot of DDC controls.

 

[ItsHot]

I guess I'm just astounded that there is a Federal law that has a min wire type spec. Seems odd to me that a building served with old pulp cable or C-rural wire would need at least cat3.

Somebody was worrying about the wrong thing!

 

[wireguru]

Somebody was worrying about the wrong thing!

easier to upgrade OSP than the wiring inside your walls

 

[brantmacga]

i use cat3 for the doorbell control in resi. and for phone lines at the hacienda el cheapo.

 

[wireguru]

While it's true that you can get gigabit to work over CAT5e, the actual 1000Base-T spec is for 4 bidirectional 250MHz channels. CAT5e is only spec'd to 100MHz, though many manufacturers do go higher. Cables can be tested up to any frequency that is supported by the test equipment, but such measurements are meaningless without the context of applications and cabling standards. Bandwidth is defined as the highest frequency up to which positive power sum ACR (Attenuation to Crosstalk Ratio) is greater than zero. I have in my hand some cable that's marked "Draft 5e" and tested to 350MHz. Should be good for 1.4 gigabit, no?

i thought 1000Base-T was 4x 125Mhz channels. The standard was devised to run over existing cat5 cabling, however 5E is recommended.

 

[wireguru]

Agree, and if the customer wants cat6, fine by me. $$$

id rather make a couple bucks less and not have to deal with the cat6 :grin:

 

[quogueelectric]

The shame of the whole thing is most people couldnt set up a network with a gun to thier head yet I sell miles of the stuff at 99$ a homerun. Just in case.

 

[peter d]

I find it funny that gazillions of miles of POTS/quad cable or whatever you want to call it worked fine for decades for phone lines...suddenly it's obsolete. I don't get it....

For phones I use cat-3.

 

[cschmid]

for running typical home phone it is still good..but for running your high speed Internet the insulation on the wire is wrong..as we move to a digital network society it becomes scrap as it can not handle the signal of the digital transmissions..but land lines are already taking a hit in the pocket book..I am curious why they wire a whole house when one jack for the cordless is all that is necessary..but to wire house in cat 5E now I can see..incoming to server then to router and bang whole house wire for Internet..but old wire should still handel analog phones just fine..

 

[MR2Di4]

My phone company buys and uses Cat6 exclusively now, apparently it's cheaper in bulk than the more traditional Cat3 we used to use. It's stiffer and a little less tolerant to abuse but if installed properly seems to work ok. Personally if I had to run wire I'd rather use all Cat5e/6 than have to worry about upgrading later to run multiple networks from a single jack location. Home runs should be the rule for everything; read: no daisy chains. Like the others said, for just POTS it will work fine, or you could use it for an intercom or other low-voltage controls throughout your house.

I am curious why they wire a whole house when one jack for the cordless is all that is necessary.

One reason I can see for standard phone jacks at multiple locations is that in the event of a power outage, a regular corded phone will still operate, whereas cordless base/satillites would be useless. I keep a corded phone at my bedside in the event of an outage/callout.

 

[LV grider]

Original Question Wrap-Up

Original Question Wrap-Up

If I'm not mistaken I believe the original question was if Cat3 is still acceptable for telephones only and the answer is absolutely YES! In fact it is better than Cat5e for a few reasons.

The "Data" guy will keep his hands off of it because he will consider it inferior and the "Alarm" guy will keep his hands off of it cause they only know how to work with quad.

A few statements along the way I feel the desire to address:

I mostly just use cat5e for everything, since it's actually cheaper than cat3 where I buy wire.

You might consider challenging your supplier on that issue.

Nortel Meridian phone system is among the more complex phone systems you'll commonly come across, and it only needs cat3 for most everything.

The Nortels are very basic. The phones connect to the system on single pair just like residential phones.

Most of the Fortune 500 companies near me have specified minimum CAT-6 cabling for several years. I have had a number of homeowner also specify CAT-6 cabling but we usually only install CAT-5E terminations

Does this mean the customer requested Cat6 and you used Cat5 jacks thus defeating the purpose of the Cat6 spec in the first place?

FCC has a minimum standard for premise wiring which requires at least cat3. The old school quad with no twisted pairs is out, yet i still see some tract builders letting their alarm guys install the stuff

The Alarm guys are installing what is required for their application not the phone guys application.

oH my Cat 3 oh no what kind of abomination are you trying to install

Not an abomination he wants to install a telephone!

What you say about CAT3 is true, but there's no upgrade path. If you install CAT3 the only thing it can ever be used for is voice or 10Base-T

Upgrade path not needed, it is for a Telephone.

for running typical home phone it is still good..but for running your high speed Internet the insulation on the wire is wrong

The insulation on Cat3 and Cat5e are basically the same, it is the twist rate and a few other odds and ends that separate the abilities of the two.

If you know what device is expected to function properly in a certain location then you will know what to run and where to run it. If your trying to pre-wire a location without knowing what is expected to operate then your odds of success are greater by purchasing a lottery ticket down on the corner.

 

[mdshunk]

The Nortels are very basic. The phones connect to the system on single pair just like residential phones.

I'd like to see what you call complex, then. :grin: You must work on some real Jim-dandy's!

One particular Nortel system I get to do MAC work on (Meridian, not Norstar :grin: )takes up about a 4x16 foot footprint, and has a pretty big encyclopedia set for a manual.

 

[LV grider]

Now that you mention it............

Now that you mention it............

I'd like to see what you call complex, then. You must work on some real Jim-dandy's!

I've worked on a few monsters like you described. They can be intimidating if your head isn't in the game,but the jest of our topic remains the same. A single pair of Cat3 from the giant footprint to one extension on the 7th floor is the same as a small system on the wall of a utility closet to an extension 20ft down the hall.

 

[brantmacga]

One reason I can see for standard phone jacks at multiple locations is that in the event of a power outage, a regular corded phone will still operate, whereas cordless base/satillites would be useless. I keep a corded phone at my bedside in the event of an outage/callout.

i recently finished a 2k ft residential job w/ a $25k electrical price tag that had ONE phone jack installed for the purpose of talking. they were going to use cordless. i did try to sell them more, but they refused to have it. there are additional phone jacks but they are behind flat panel tv's and are there to connect the dish receivers.

 

[pmiranda]

Our house has been phone-free for years. I'd be pretty ticked off if I found the only cable run to a room in a new house was CAT-3. It's good for getting from the demarc to the closet where all the other data/comm gets home-run to, but it's actually getting hard to find at the big box stores.
For future-proof in my new house, I just ran 1-1/2 conduit from where the home theater is going in to the homerun closet. Hopefully the last time I'll ever have to crawl inside a vaulted ceiling!