Fibre installation query FREE cabling and networking Helpdesk
 Question by Pete Hinxman posted 16 Sep 2004
 Fibre installation query

I have a question that I wonder if anyone can point me to documentation (or another mailing list or newsgroup) to clarify, that covers UK fibre installations good practise or regulations.

We have installed composite fibre (multi-mode and single-mode) on many runs around the university ducts, and have only made off the multi-mode strands, leaving the single-mode strands coiled up in the patch panels.

Our technicians have both been trained in making off multi-mode fibre, and, as we have not needed to use the single mode, we held off training them on it and on buying the single-mode equipment.

We have now sent one on a training course for single mode and now have purchased a fibre-splicer that does both multi-mode and single-mode.

The time has now arrived to start using the single-mode fibres. But we are unsure with one aspect.

As the patch panels currently contain lit multi-mode fibres, we were wondering if the far end multi-mode fibres should be disconnected while the near end single-mode fibres have their pig-tails spliced on, or whether that is just over cautious.

Any thoughts from installers (preferably with links to documentation), or just comments on what you would do, would be greatly appreciated.

 Answer by Dmitri Abaimov posted 16 Sep 2004
Dear Pete,

On the issue of general installation-related information I would suggest that you consult with manufacturers of the equipment that you are planning to use. This info is normally available on the manufacturer's website. Pay it a visit, you can normally find brochures in the "Products" section. Your next choice of information source can be the company you are buying the equipment from. These are people interested in your business, and they normally are responsive to your calls for help. I always get support from my distributor although sometimes the situation requires to talk to the manufacturer.

On the question about the pigtails I can say that you do not have to disconnect any multimode when you are working on the singlemode strands. There is no interference or anything of this nature, so there is technically really no reason for that. One the other hand, you definitely want to notify the users on your network that downtime is possible when you are working on the singlemodes. The reason for that is simple: working in a tight space of the fiber cabinet you can accidentally pull on a fiber or drop a tool or else, so a slight chance to damage existing fibers in this situation is inevitable. Since you are familiar with MMF, repairing this would not be a problem (especially now that you got the splicer), but for some (considerable) time people on the broken MM link may be out of service.
By saying the above I am obviously assuming that you are not going to look into the fiber adapters without dust caps while working. But then you should not have any unused terminated fibers without dust cups in the first place, so you'll be fine.
One other thing I wanted to mention is that you should verify if your existing fiber cabinets have special space for splice cassettes if you are planning to use pigtails. A regular termination-only fiber cabinet is not going to hold the splices safely, and you will have to install additional shelf right beneath (or above) the old one.

Good luck!

Dmitri Abaimov, RCDD

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