Considerations when extending a Cat5e PoE cable within interior walls

[Peter B]

Good afternoon!

 

I'm looking at moving a wall-mounted digital intercom unit to a place further down a hallway. It's connected with a Cat5e cable, and powered through PoE running over the same cable. It's not possible to move or replace the cable, so it will have to be extended.

 

The two available options seem to be a female-to-female RJ45 extender, or a female-to-male Cat5e cable. Both support PoE. My main concern is that the cable is powered by a source outside of our control. The intercom unit draws negligible power whilst idle at most, but theoretically PoE is able to support much higher power capacities (100W according to IEEE 802.3bt). However unlikely, malfunctions in the intercom system could create for such peaks, I guess.

 

Since the extension will happen within the interior walls (that will be plastered over), my question is whether there are heat or insulation considerations to take into account for either of the available options?

 

Many thanks,

Peter

 

[Carrerahill]

Terminate the cable within your property, possibly even at point of entry, so that the joint can be accessible, if it was me I would solder and heatshrink it maintaining a good twist as close to the joints as possible enclosed in a flush box and cover, my alternative would be to terminate the cable to a flush/surface RJ45 socket, then plug another cable into that out to your intercom.

 

This option permits you to run the new cable exactly where you want it and the connection will be accessible - do not plaster over. Even in SELV systems like this it really is unacceptable. If worst comes to worst put a 1G blanking plate on the wall down low.

 

Only issue here might be distance, what is the current distance do you think?

 

Is this your own system or part of a system in a multi-occupancy building?

Edited July 7, 2021 by Carrerahill

[Peter B]

Thank you for the very clear response, Carrerahill!

 

This is a communal intercom system part of a multi-occupancy building. The cable comes in above the front door, together with all other cables & pipes, and has been terminated exactly halfway down the nearest wall. No spare length has been accounted for. The cable is terminated with an RJ45 connector plugged directly into the intercom unit.

 

Installing a flush box—especially if it sported two connected RJ45 outlets, which would have my preference, would thus be very visible. This is what we're trying to avoid, but of course not at the expense of safety.

Edited July 7, 2021 by Peter B