Part 2: Frequently Asked Questions about Emergency PoE Lighting and Smart Building Technology
September 27, 2019
When Igor's Founder and CTO, Dwight Stewart, joined Tyler and Maria from PoE Texas on the Converge PoE Live Stream, many questions about PoE emergency lighting capabilities came up. We've summarized the questions from the show and we've added some additional context that we did not have time to touch on while live!
Watch our events calendar for updates on how to see Igor and Tyler live AGAIN on October 1st. Their rematch will be streamed on Converge PoE live while at BICSI Fall 2019 Conference.
Missed Igor on Converge PoE Live Stream? Watch it here.
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Let’s talk about UL and back-up power lighting. One of the biggest challenges is emergency back-up lighting. It sounds like you have a solution to have emergency lighting on your fixtures with UL924 rating.
[Dwight] Yes, that’s a pretty special thing. Think of the lights as a bunch of individual components and with our centralized solution, you can put a UPS on the power supply to be powering those fixtures and not have batteries on each fixture. By not having to have batteries inside the fixture, that really reduces the complexity of the fixture, the price, and decreases the maintenance as batteries only last 5-7 years before being replaced. And around 20% of fixtures have to be emergency, and that’s a lot of maintenance.
Our node has also been tested for lifetime expectancy by one of our OEMs. They found that our nodes went more than 30 years equivalent during testing with no failures. Typically, an AC/DC driver lasts 5-7 years. LEDs pretty much last forever, though they can degrade over time. The Igor node lasts 30+ years, and LEDs that last decades, and you remove the battery – now you’ve made it a no-maintenance type of application and decreases the total cost of ownership to allow you to spend your money more wisely.
[Tyler] From my input as an owner, the battery thing that Dwight is talking about requires maintenance people to walk around, often with large poles, to poke the button to test batteries annually with a fire marshal. Then, when the battery dies you have to grab a ladder or lift to get someone up to the light to change the battery. I recently saw a light that was 30 feet up in the air, over some beautiful architectural stairs, so it had to be emergency designated. To change that battery would require a mechanical lift to get someone up there to change the lights. What I like is the UPS back in the IDF room running those lights, so when the battery goes bad you get a beep or notification to change it, and you can do so quickly.
[Additional Comments by Igor] Our UL924 Emergency Lighting Node recently won a Sapphire Award from LEDs Magazine and UL leadership provided comments on our technology and win. To read what they have to say and more about the award, check out our award announcement post. Or, to see a picture of an example of an Emergency Node and the initial announcement with UL commentary added later, click here.
Is it correct to assume that PoE lighting would be safer than 110 V wires that are currently run for lighting?
[Dwight] That is absolutely true. That’s another great strength. It is a Class 2 install in the UL spectrum which can be installed by IT staff instead of requiring an electrician. It also improves the safety. Imagine being a retail space and you want to change your floor layout. You can change things around more freely – simply unclick the socket, move things around, and plug it back in without worrying about getting electrocuted.
[Tyler] I would add that the maintenance question is not an insubstantial question. You come in, set up your lighting, and then you need to move a light six inches and you have to use an electrician at $120 an hour. Usually the biggest problem with putting AC outlets in the ceiling is that it’s a one-trick pony. You get one use out of it, but a networked cable doing the same thing can be switched from a light to a camera at any time. And I can move it around easily with in-house staff. It’s not small savings.
When it’s DC power, under 60V, and it may step down when you do AC power to 24V…the code is less clear. The simple answer is go for less than 60V then it is Class 2 and safer to install. Little tip – we have done the game where you lick the 24V power supply and it does tickle…I would not encourage you to lick it.
[Dwight] I will say, with Power over Ethernet, there’s a whole negotiation process. When you have a wire off a PoE switch, you could lick the wire because there is almost no power going over the wires at that point. You have to plug it in, then the switch negotiates and sees the signal from the devices plugged in, sees that it is a PoE device, it will then elevate the power and it goes through that negotiation. So there are a lot of steps it goes through and it’s safe the whole time.
For egress lighting to function, the components need to be UL 924 rated. The one piece of equipment in the power chain is the PoE switch, which is not UL 924 rated. So how does that work?
[Dwight] UL 924 requires that the emergency devices themselves have to be 924 listed, so our node is UL 924 listed. So as long as the other components don’t change their function in emergency node, then they just have to be powered by a UL924 source. So if you have a generator out back and it can provide UL924 power so then the components between the generator and the node don’t necessarily have to be UL924 so long as they are not changing their function or behavior between normal and emergency mode.
So you have to make sure the power connected to the PoE switch is UL 924 certified via a generator or vending partner or other source that satisfies that requirement. If you want to get a site certified, then you need to get the right power supply. Remember that lights have to turn on in emergency situation in less than 10 seconds and last for at least 90 minutes on emergency power. With our centralized backup, our lights turn on within five seconds and, say you have a generator, you can size your inverter however you want and go well beyond 90 minutes – maybe even days. Batteries on light fixtures will probably hit the 90 minute mark.
[Tyler] I’m also going to add that a midspan in the backup power supply is a better alternative than some of the higher-power PoE switches because high-power PoE switches often will take a little bit of time to boot up, configure, and start communicating. Where a midspan, in case of an emergency, the light will respond by itself. Therefore, if you have a midspan and the power going out, it switches over, and ideally the gateway and server are on the backup power, but if you didn’t the midspan is a very fast alternative to getting the power back up. I would suggest considering a midspan for the UL application. .
Where is the loss of normal power sensed and acted upon in a system with the UL924 node?
[Dwight] Our solution is patent-protected proprietary to us, but what we do is that we have is a signal that comes from somewhere, which typically sits on the same machine as our nuk and that signal sends a heartbeat every two seconds to the emergency nodes. So as long as that signal is interrupted somehow, it triggers emergency steps. For example, there is a piece of network equipment that is between the server and the nodes on normal power and then it drops off so the signal is no longer happening between the software and nodes. So as long as you’re interrupting that signal, that’s all you need to trigger the emergency function.
It’s about the mechanical function, it’s not about the software function of deciding when to start and stop the heartbeat. The signal is always happening, it’s really about whether the network is energized to be able to route that signal onward.
[Additional Comments by Igor] Igor’s lighting technology meets safety standards ASHREA 90.1, Title 24, IEEE standards, NFPA NEC, CE, and UL924. This applies to several applications, such as: daylighting, demand response endpoints, automatic countdown wall controls, manual dimmers, manual on/off switches, receptacle control, monitoring, remote signal control, tuning control, and occupancy & vacancy modes.
Igor accomplishes the UL 924 Emergency Lighting support by using the “heartbeat” method. The Gateway software sends out a “heartbeat” signal every second to the Igor emergency Nodes to keep them operating in “normal” mode. If a Node doesn’t receive the heartbeat within a period longer than 2 seconds the Node will enter “emergency” mode and automatically turn on any connected emergency lights at the pre-configured dimming level (default 100%). When the heartbeat signals resume the Node will return to normal operation.
The interruption of the heartbeat signals is typically triggered either actively or passively based on available monitoring of building power. Active power monitoring of the building utility power requires additional equipment to monitor each power phase and alert the Igor Gateway if one or all phases are lost. Passive detection would typically involve a network component such as a data switch between the Gateway server and the rest of the lighting network that is not on a UPS.
Patent Reference: Stewart, Dwight L. U.S. Patent 9730299B2 filed July 16, 2015, and issued August 8, 2017.
What about software control of the PoE switch output in an emergency? How is software affected?
[Additional Comments by Dwight] You cannot depend on software control during an emergency, because commands may not reach the lights properly during an emergency, which then results in no emergency lighting.
Igor has a patent and UL924 Listing on PoE emergency lighting that removes the need for software control, and also removes the need for batteries within light fixtures. The network switch and software do not change their operation during an emergency, and therefore do not require UL924 certification. Instead, data is constantly sent from the software to the emergency nodes. The PoE network switch powering the nodes is supplied by a UL924 power source such as a UPS, invertor, or generator. A network switch on non-emergency power is placed between the PoE switch and the software. When power is lost, that non-emergency powered network switch goes offline, the data is no longer received by emergency nodes, and the nodes go to a preset emergency lighting level.