I am always pleased to receive your magazine and I particularly enjoy reading installer tips, as a lot of them are very interesting. I have been a cabling installer, cable plant designer, troubleshooter, and general cabling dogs body for many years. The logic behind David Lacasse's installer tip in your September issue ("Give fiber redundancy with copper," page 48) does not make sense to me.
We would install a fiber backbone for several reasons: speed, reliability, and (most often) distance limitations. We often install fiber by attaching a leader to the reinforcing members of the cable (usually Kevlar) and pulling the leader.
If fiber is pulled through a location that renders it vulnerable to damage, such as a machine or manufacturing environment, how would pulling another cable in the exact same route provide redundancy? If indeed the fiber were damaged, it would stand to reason that the backup cable would also have a very high probability of being damaged. Also, the fiber is probably covering a distance that a copper cable would not be suitable for. If the fiber failed and the copper was still intact, using it would almost certainly be seriously detrimental to network performance.
I am trying to understand how attaching the fiber to the copper backup cable when pulling it will alleviate any of the pulling tension? It will have the exact same tension applied at the point of attachment as it would were it attached to a pull rope or string.
Finally, there are some networks that use a redundant backbone configuration (such as token ring). It is usually recommended to route the secondary backbone a completely different direction to reduce the risk of both failing in the event of a mechanical break.
I recommend, as a backup plan, that the technicians who service the network keep on-hand a supply of couplers, crimp-on fiber connectors, or quick-lock-type fiber splicers which could be applied quickly as a temporary fix until the backbone is replaced.
Most companies know when someone has been working in an area that could have affected their network cabling. Asking maintenance and construction crews first is a good place to start. Then call in the professionals.
City of Fayetteville, AR
BNC vs. F connector
In your October 2001 Product Update (see "Coaxial cable: behind the video," page 58), perhaps you meant to say "F" connectors, rather than "BNC" connectors in the first column?
The center conductor is not exposed on a BNC-type connector and they work quite well with either stranded or solid-center conductors. The F connector, however, does expose the center conductor and can only be used with coaxial having a solid-center conductor.
Mike is correct. The BNC connector has a pin that goes over the conductor, then it is inserted into the BNC connector housing. The F connector does expose the conductor. The F connector is what you would typically see on your coaxial cable at home.
Quabbin Wire & Cable Co., Inc.