Chris 15 has it. Still needs emergency
power - generator or inverter are common but not only option - for both lights and the control -
DMX bypass here.
There are other options. I use the
DMX bypass to drive relays on as well for
emergency lighting on
stage and backstage.
ETC and I suspect others have some other options that meet code requirements.
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 . . .