Emergency DMX takeover

Some brands of LED House / Work lights have a UL924-listed programmable internal default setting they can go to should the DMX source be interrupted. So, if the DMX signal system from the House / Work Light Controller goes-down, and there isn't a UL924-listed DMX transfer device, then the lights don't wake-up stupid, they wake-up to a predetermined level.

This does the same thing as a separate UL924-listed DMX transfer device that controls many lights. However, I'd rather have 90% of the House / Work lights come-on correctly (10% failure), than have none of them come on if the single separate UL924-listed DMX transfer device fails. Of course, using the 'department of redundancy department' approach would have you use the separate UL924-listed DMX transfer device AND House / Work Lights that have integral UL924-listed DMX transfer devices.

Another consideration is that the ETC device only drives up to 31 light fixtures, then you have to buy another one for the next 31 fixtures, etc. For a typical auditorium with 100+ lights, this means at least 4 of the transfer devices may be required. The Strand device will drive four lines of up to 31 fixtures each.

The illumination level required by the Fire Code is generally much less than 'FULL ON', so you can set all the LED lights to maybe 10-15% (whatever it takes to meet the code) and the electrical load on the emergency power system (generator / inverter) is significantly reduced. Less load usually means it costs less money. Example: If you have 100 houselights that can normally provide about 50 fc at FULL-ON for 200 watts each, then 100 of them at 10% could provide about 5 fc in a nice even coverage at about 20 watts each. This reduces the emergency power load from 20,000 watts to 2,000 watts. A 2,000 watt UL Listed battery type inverter that is self-monitoring and automatically reports to the Maintenance Department via pre-programmed emails will cut the long-term maintenance labor costs way down from dealing with a plethora of 'frog-eye battery packs'. The initial cost and long-term maintenance cost / hassle of a diesel generator is sometimes prohibitive.

This system design approach provides a whole-house emergency egress illumination rather than the spotty blinding effect of a bunch of 'frog-eyes'. We all know the batteries in the 'frog-eyes' don't get tested and replaced as frequently as they should, so by centralizing the load to a generator (or a single large inverter / battery) the over-all cost of the building is less. You don't need to pay for both LED houselights AND a separate 'frog-eye' system (and all the attendant labor and materials for wire and conduit). You also get the added aesthetic benefit of no 'frog-eyes'. Damn, those are soooo ugly in an auditorium . . .


ETC now makes a version of the DEBC with 6 outputs.

Unsurprisingly when looking at the cost of UL924 certified fixtures, the cost difference between having certified fixtures vs a UL924 front end control is quite high. The certified DMX fixtures having nearly a 20% premium over the standard fixtures. Now IMO, there is another downside of having the fixtures be the DMX transfer, what happens if you lose the DMX signal in a non emergency scenario... then you have your houselights/worklights forced to full because the signal is gone (intentionally or not) I've seen brands that expect a normal power sense and are fed via an emergency source, but the transfer function happens when the sense feed is lost. At that point, the cost of running two power feeds to fixtures is more than likely equal or greater than having the front end emergency control system.

I was also under the impression that a UL924 device had to have a readily accessible test switch for that function (a-la ETC DEBC)
 
When you talk about an LED fixture that includes its own transfer, the ones I'm familiar with basically sense power loss, not loss of data, and come on powered by their own battery. And of course the ETC Arc series transfers to an emergency circuit upon loss of normal power. Any front end scheme relies on loss of power, not data.

Am I simply wrong or is there another group that detects loss of DMX? Seems pointless since it's really loss of power that's usually sensed and nothing assures loss of DMX in an emergency.

PS 0-10 control is I believe fail safe in that loss of low voltage sends fixture to full.
 
Not that these replies aren't helpful -- well, more 'interesting' -- but remember, this is a *restaurant*, not a theatre. Different requirements, no?

I would be willing to put a small wager on the good old battery-backup-exit-sign-flood-light-combo being enough to satisfy the local codes for a restaurant.
 
I would be willing to put a small wager on the good old battery-backup-exit-sign-flood-light-combo being enough to satisfy the local codes for a restaurant.
Sure. Maybe a pair of bug eyes on a battery pack if the space is large. Have done that in very low cost theatres. Transferring houselights is a nice and good way to go but seldom, initial cost anyway, not more expensive than battery packs. A couple of troffers with the em option work well too - and with a switch are useful for clean up - or "the party is over" look.

PS I think good practice to power these off a constant circuit in house dimmer rack or off and panel house lights are fed from, same phase , so a one panel or one phase leg failure doesn't defeat the intent.
 
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I would be willing to put a small wager on the good old battery-backup-exit-sign-flood-light-combo being enough to satisfy the local codes for a restaurant.

Depends on the aesthetic intent of the restaurant... I've installed a few Unison systems in high end bars and restaurants that want that level of control, and the emergency lights usually end up falling under my control once I explain to the engineers we don't need to use the bug eye'd batteries with a simple transfer switch or DMX Bypass Controller.
 
Depends on the aesthetic intent of the restaurant... I've installed a few Unison systems in high end bars and restaurants that want that level of control, and the emergency lights usually end up falling under my control once I explain to the engineers we don't need to use the bug eye'd batteries with a simple transfer switch or DMX Bypass Controller.
Except then you also need emergency power, generator, inverter, or other, which along with the transfer switch or DMX bypass, inevitably costs more to much more. Yes if you have a generator otherwise, it might be justified.
 
PS 0-10 control is I believe fail safe in that loss of low voltage sends fixture to full.

But when is UL924 required? I have had several manufacturers tell me they can program their fixtures to come to full on signal loss. So far we have wound up with other solutions, but I've been pondering the ramifications. To be clear this is not a battery backup/ transfer scenario, just trying to duplicate the 0-10V function that has long been accepted.
 
But when is UL924 required? I have had several manufacturers tell me they can program their fixtures to come to full on signal loss. So far we have wound up with other solutions, but I've been pondering the ramifications. To be clear this is not a battery backup/ transfer scenario, just trying to duplicate the 0-10V function that has long been accepted.

From NEC 2017:

700.2 Definitions
Luminaire, Directly Controlled.
An emergency luminaire that
has a control input for an integral dimming or switching function
that drives the luminaire to full illumination upon loss of
normal power.

Informational Note: See ANSI/UL 924, Emergency Lighting and
Power Equipment,
for information covering directly controlled
luminaires.

700.24 Directly Controlled Luminaires. Where emergency
illumination is provided by one or more directly controlled
luminaires that respond to an external control input to bypass
normal control upon loss of normal power, such luminaires
and external bypass controls shall be individually listed for use
in emergency systems.

Therefore, if a luminaire has a control input, it must be UL924 listed in order to be used for Emergency.

There you have it.
ST
 
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Since I have not replied on this type of "directly controlled luminairs" for emergency lighting what do they do upon loss of control input?

Maybe more constructively, how do you turn them on if they have lost data but not normal power, since loss of normal power is not assured in an event requiring emergency lighting?

I believe in assembly occupancies that having trained and competent people in charge and in control in an emergency situation is always preferable to automatic and pre-programmed control, and that history proves this. Codes, especially as influenced by emergency responders, don't recognize the value of a person making real time choices in events with lots of people.
 
Codes, especially as influenced by emergency responders, don't recognize the value of a person making real time choices in events with lots of people.
True, but codes regarding equipment can't assume the competent person is always available.
 
The emergency lighting is designed to turn on during a power outage, by battery or generator power. When power is lost, the competent person probably lost any control over any lighting, because the lighting console, house light station, and dimmer rack have all lost power. While it would be possible to power those devices with emergency power, that is expensive and open to human error. It doesn't work if the lighting console gets plugged into the wrong receptacle.
 
True, but codes regarding equipment can't assume the competent person is always available.

Except the Life Safety Code and the IBC rely upon crowd management as a fundamental part of the plan top assure safety, and that includes live real time direction, seeing where there are too many people, etc. The codes not only assume but require a competent person be available on on duty in assembly occupancies. Long ago Mr. Foy did this at the Iroquois Theatre here in Chicago and probably saved quite a few souls. Other recorded instances are similar. And forget the hollywood images of wild anti-social behavior in these events. Talk to or read the accounts of survivors and read the reports of disasters and the conclusion is clear that people behave extremely well and altruistically in an emergency.
 
The emergency lighting is designed to turn on during a power outage, by battery or generator power. When power is lost, the competent person probably lost any control over any lighting, because the lighting console, house light station, and dimmer rack have all lost power. While it would be possible to power those devices with emergency power, that is expensive and open to human error. It doesn't work if the lighting console gets plugged into the wrong receptacle.

What happens if power is not lost, and there is an an emergency? The systems I design do include powering lighting and driving it to code required levels of illumination in the event of a power failure, up to and including in any failure in the last load center, dimmer panel, or relay panel that normally serves this lighting. And all of these systems are subject to human error or negligence. Assembly occupancies still are allowed to rely on a the normal sound system on emergency power rather than alarms of pre-recorded messages on red tin speakers because experience has shown the house systems and live people are much better at managing crowds in an emergency than all the pre-planning and logic that any number of experts might try to set in advance. Simply sensing loss of power doesn't tell you much about the emergency, or even if there is an emergency.

I recall two events (may be more) where I was in attendance and had a certain role in the operation of the theatre where power failed and there was no emergency or immediate threat. Maybe a car took out a pole miles away or something, but no threat. Another more serious fire incident and the lighting remained until I asked the operator to turn on the house and work lights, and turn off the stage lighting (which predictably was the cause of the fire.) All of these events were handled with more safety because people were in charge and could control the situation.

BTW there are other options besides (local - emergency) generator power or battery. Just worth keeping in mind. A couple universities I've worked on have their own separate constant emergency electrical service. Probably rare and getting rarer, but does exist.
 
Since I have not replied on this type of "directly controlled luminairs" for emergency lighting what do they do upon loss of control input?

Maybe more constructively, how do you turn them on if they have lost data but not normal power, since loss of normal power is not assured in an event requiring emergency lighting?

I believe in assembly occupancies that having trained and competent people in charge and in control in an emergency situation is always preferable to automatic and pre-programmed control, and that history proves this. Codes, especially as influenced by emergency responders, don't recognize the value of a person making real time choices in events with lots of people.

1. Some types of directly controlled luminaires (0-10V is one example) go to full upon loss of control input. Others, like those that accept DMX512, typically do nothing on loss of control input, and the ON functionality comes from listed emergency control equipment.

2. A normal/emergency luminaire is not acting as an emergency luminaire (by Code defintion) if normal power is present. In such a case (for instance, a sick audience member, or a terrorist act), the normal control system might have a PANIC function, where it would be most likely for all lights to be manually energized, not just those required to reach minimum footcandle levels as in a loss-of-normal-power emergency.

3. Emergency lighting systems mandated for egress in loss-of-normal-power events cannot rely on human intervention to make that happen, no matter how well trained the staff.

ST
 
3. Emergency lighting systems mandated for egress in loss-of-normal-power events cannot rely on human intervention to make that happen, no matter how well trained the staff.

ST

True, by law, but I am more concerned by the many emergencies not accompanied by loss of power and good design for that event, which I believe is more common than the loss of power event.

(And hate that use of the word PANIC - a complete red herring.)
 
A 0-10V system *can't* go to backup on loss of control signal; loss of control signal is indistinguishable from "Brightness 0"; that's most of the entire point behind DMX, no? :)

Err...no. You're thinking of "theatrical" 0-10V, when 0 volts is off and 10 volts is full. Typically architectural luminaires with 0-10V control (like fluorescent balllasts or LED drivers) operate differently. They have a current sinking input that is pulled-up internally, so when the control signal is disconnected or goes high impedance, the luminaire goes to full.

So, in this case, there is a difference between "open circuit" and "zero". Many emergency controllers simply interrupt the 0-10V control line with a SPST relay contact upon loss of normal power.

ST
 
No, I was thinking of "the only 10V dimming system I've ever heard of in a 35 year career that's touched on damn near every discipline that wasn't medicine." :)

I expect that it's probably suboptimal for both of those to be called "10V dimming". :)

And this *is* a theatrical forum, after all...
 
No, I was thinking of "the only 10V dimming system I've ever heard of in a 35 year career that's touched on damn near every discipline that wasn't medicine." :)

I expect that it's probably suboptimal for both of those to be called "10V dimming". :)

And this *is* a theatrical forum, after all...

And damn those architectural pukes for attempting to usurp our standard, anyway! :)
However, if we just count luminaires, guess who's winning? Don't forget, we threw this control method in the garbage in 1986--the year DMX512 was adopted (I was there). It shouldn't surprise us too much that someone else modified (perverted?) it for their market's purpose!

Cheers
ST
 

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