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Anyone's still using keyed RJ45s?

Hello everyone!

Have a spec with keyed RJ45s called for. You know, reasoning that people should not be able to plug a keyed data cord into a phone outlet and fry their NIC. Probably made sense 10 years ago, but with a free NIC that you normally get these days and central pins shortened to the ground anyways, makes not sense to me. Pain in the neck to deal with, and the price is too high, but the architect insists.

Can anyone post any real-world feedback on using those? I have never had to actually use keyed cords, and I'm preparing an RFI with some data about exactly how much it is a PITA to have keyed jacks/cords. Just need couple juicy examples.

Anyone?

Reply to
Dmitri(Cabling-Design.com
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I haven't even seen a keyed RJ in about 6 years!

I don't know of any NICs currently being manufactured that use a keyed plug, they kinda died before Compaq bought DEC. One ploy you may try would be to hand the architect a keyed patch cord and tell him to plug it into their computer. That might be the best example.

Reply to
Justin Time

Isn't an ethernet NIC transformer-coupled and really hard to fry ?

OTOH, lots of new PCs have the NIC on the mobo and it it does the mobo is effectivly dead.

The lifetime cost of custom-spec cable plant might excees the cost of any damaged equipment.

Reply to
Al Dykes

Yes, and somewhat. There is an isolation transformer required to read the differential signals.

The "hard to fry" is relative. Ethernet survives hotplugging extremely well. But is still very vulnerable to surges (lightening induced ground differentials). I've seen more dead hub/switch ports than ethernet cards.

-- Robert

Reply to
Robert Redelmeier

Or point out to them that if they have to buy special patch cords with regular on one end and keyed on the other, it will cost a whole lot more, not to mention that the users will have to figure out which end goes where. :-/

Reply to
Watson A.Name - "Watt Sun, th

Well, if you fry a NIC on the mobo, then assuming nothing else happened, you just pur a NIC in the slot and turn off the mobo NIC in the BIOS. Of course some lusers haven't the ability to even insert a NIC into a PC slot..

Good point. One other thought. The keyed jack is on the wall plate. But is the patch panel also keyed? Seems to me that it doesn't have to be, so no problem with the switches. Anyhow, I can't remember ever seeing a keyed jack or plug, altho I did get a crimp tool with the keyed hole in it.

On our last job, the contractor put in RJ-45 connectors for the phone jacks. The scary part is that our digital PBX puts out 54VDC at about

150 mA, which makes for a nasty spark if it gets shorted by the punchdown tool. I haven't heard of any problems yet, tho and it's been two months..
Reply to
Watson A.Name - "Watt Sun, th

(snip regarding keyed RJ45 jacks)

One place I used to do work with had keyed jacks, and supplied patch cords with keyed plugs on one end. For direct connect that was fine, but in some cases we needed a hub, which the university also supplied.

We then had to remove the key with a knife so that the plug would work with the hub. It isn't so hard to do. I believe the jacks are the same price.

-- glen

Reply to
glen herrmannsfeldt

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