The Problem with Power over Ethernet

Power over Ethernet Problems

Power over Ethernet (PoE) has been heavily promoted as the future of lighting and controls – with data cables replacing power cables to make installing luminaires easier and cheaper. Lower powered LED lighting has opened up the possibility of low voltage Ethernet cables being able to carry the required voltage to the luminaire and create an instant controllable network for lighting.
But, it has limitations that you should be aware of.

Having your lighting as part of your computer network has obvious potential security issues. Ever lost a printer or had your network down for a period of time. Tying the whole thing together makes one problem into a multiple problem. This can be solved by ensuring the system is sufficiently robust and has fail-safes to guarantee the presence of the lighting installation.

Ok, these don’t happen very often but they do happen. Often, they are brief, but interruptions to computer power and incorrect shut down procedures can result in glitches which will mean you’ll need to reconnect the lighting to the network. All this work to fix it will most likely be done in the dark. The way around this is to have a power supply system that reliable and has protection from surges and outages.

Your lighting is now part of your computer system and will need to be compliant as such. This limits the lighting options you have available as the lighting load must be designed to work with the rest of the network. You don’t want to risk unwanted power issues across your whole computer network. Another limitation is making sure that the right load reaches the fixture. All cables have resistance to the flow of electricity and it is affected by electrical load and length of cabling. If you reduce the voltage for say an LED fixture and increase the load and increase the length of cabling then you could end up with no light at all. This would need to be designed out by an electrical engineer who will ensure the right voltage and load is getting to each fixture.

Picking up on that last point – you need an electrical contractor to make sure the system is going to work in your environment and although Ethernet has ‘plug and play’ capabilities – you need to make sure they are all set up for Ethernet to begin with and the voltage and loads have been considered.

We’re gonna need a bigger boat…
If you are adding all your lighting into your Ethernet cabinet – do you have enough ports free? Are you going to need a new server cabinet? The servers produce heat that also needs to be dealt with. Something to be aware of before your office floorplan needs to change to accommodate your lighting.

Some like it Hot
The power rating of Ethernet cable and terminal connections have small losses. These accumulate over large areas and generate small amounts of heat in each connection. Small amounts of heat are not a problem, put that over an entire ceiling and you might start to see an extra load on your HVAC or worse still, failure in the system through overheating. Good quality equipment has considered this limitation and tried hard to account for it but as needs expand is Ethernet really fit for a purpose it wasn’t designed for?

The Bright Side
There are examples of times where PoE can absolutely be the right answer for a specific need just take a look at this example of retrofitting in an old building where running cabling would have been very difficult.

While PoE is an innovative reimagining of existing technology it has enough draw backs to make you think twice. Tenzing Energy Solutions can listen to your specific needs and specify the system that is ideal for you and will be ready to grow and evolve with your business. Talk to one of our advisors to get honest advice on your specific needs.