Extending from the L2-PDM via 25 pair cables

Top tips on configuring and wiring for LumenCache.
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Joined: Wed Nov 11, 2020 10:46 pm

Extending from the L2-PDM via 25 pair cables

Post by bn »

This question is probably unique to my particular installation because of air tightness constraints, there are no penetrations through the building envelope except for a few well placed conduits that are capped/sealed. I have located all of my PDM in a central location in close proximity to the outside wall which is shared with a garage. All outside wiring for LC lights, 1-wire sensors, Ethernet, audio, etc, are ran into the garage, to a location that's at most 45 ft (as the cable path goes) away from the PDM inside the house. I have conduit through the wall into the garage, stubbing up directly below where all of the outside cabling has been pulled to. I've considered the actual number of pairs (12V, switch, DC+, DC-) needed to service the outside LC lights and although I could pull dedicated Cat5e runs for each LC light into the garage, I want to be ready for the future and install infrastructure once.

What are your thoughts on using 10 ft of Cat5e from the L2-PDM to a BIX strip, extending the 45 ft into the garage via a 25 or 50-pair 24 AWG tie cable (standard telecom grade CAT3) terminated to another BIX strip, and then continue on to the LC lights over Cat5e? Termination to a patch panel and keeping with the RJ-45 standard would also be an option, but at an additional cost.

A single 1/2" cable in a 2" conduit will be much easier to seal than a bundle of 13 or more Cat5e, will look cleaner, and provide room in the future if additional wire is installed (if ever needed). Careful cable management, labeling, and testing would be critical. I cut my teeth in telecom terminating BIX and 110 blocks, searched for jumpers in poorly lit closets of greasy jumper wire, felt the tingle of ringing and T1 voltage on my finger tips while sniffing for the tone of a phone line, so I'm not too put off by the idea of having to be careful and meticulous. This sort of solution wouldn't be for everyone.

I recall a few instances where alarm contractors used riser pairs to deliver DC voltage to a remote ringer, or 'borrowed' a pair from a near by voice jack in order to hook up a door relay..

If the above doesn't sound like an absolutely terrible idea, what are your thoughts on using pairs from the same 50-pair cable for motion sensors or door NO/NC relays? Would/could induction from the DC pairs be an issue?

As for the network drops outside of the house, I plan to install a small 12-port PoE switch in the garage and trunk back to the core via fiber, though the same conduit.

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Re: Extending from the L2-PDM via 25 pair cables

Post by dc »

I did the math on the temperature increase in the cable and it's ok with 300mA CC loads but not good for above that. For that reason I would like to say it's not recommended to use 25pair cable at this time. The beauty of LC is we can have new transmission tech in future modules, but we should wire for all conditions.

It's super easy to run a Cat5 for the PDM Comm Bus and a 10/2 wire for power and have remote distribution panels. The PDM Comm bus protocol ties everything together just fine for control and switching.

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