PoE question nets a range of responses

Aug. 16, 2019
Feedback on our previous PoE blog has shown a range from compliments to concerns with regard to the technology.

Wow! Not my usual style of introduction, but I had no idea there would be such engaging commentary on Power over Ethernet (PoE) for lighting after I wrote about it back in July. Some of you in the audience read the blog initially, while others came to it through a later newsletter in which chief editor Maury Wright mentioned the topic and how our conversation about PoE might be expanded with feedback from the readers. I am still reading through and digesting the ways in which these responses may be utilized for a future perspective piece, so I thought I’d tease out a few connecting threads from our peers in the industry.

1. Power down — reduce unnecessary line voltage.

Several commenters have mentioned the excessive amount of power running over standard lines to newer LED lighting, and the power conversion problems with AC to DC in LED installations. Some say that if utilized properly, PoE could support the promise of greater energy savings by increasing efficiency. However, opinions on “proper” implementation of PoE certainly vary. See below the next point of interest.

2. Current cables and standards may create kinks in the situation.

There’s been some observation that the abundance of standard Ethernet cable may contribute to the demand for using it up in new building network applications that include lighting. At the same time, power losses over the distances seen in building networks is a concern. One commenter has cited that the national electric code (US) “does not permit total voltage drop at the load of more than 5%,” and conversion losses of the power supply may not be taken into consideration. A single pair Ethernet standard may provide some solutions in terms of simplifying wiring, reducing cost, and increasing efficiency, according to a couple of the respondents.

3. Ethernet could be a valuable emergency tool.

A “shock/fire-safe lighting power distribution design” could propel demand for PoE systems integrated with general lighting, emergency backup lighting, power supplies, and beacons for safe egress and emergency notification. Could this be what a networked building needs for true intelligent operations? Some of our peers hesitate to label PoE as “the” solution for emergency systems when small batteries inside each luminaire could also do the job for the minimum required time at the minimum required light level, as one observed. And wireless options like Bluetooth Mesh are still garnering plenty of attention; a feature from earlier this year examined the possibilities for emergency management systems, for example.

We don’t have all the answers, but it sure is stimulating conversation.