I'd ask "what do you consider a theatrical
relay system?"
This is an important
point. Most commercial buildings now have Lighting Control Panels (
LCP's), that are just
relay panels for lighting loads. I haven't gone through the spec sheets to compare side by side, but there's likely very little advantage in getting the
ETC brand name on the
relay panel versus the
LCP's from a few dozen other manufacturers. There are tons of companies making
relay panels and few tangible differences between them. Distinctions between them, if I were to guess, might be whether you can load the circuits up to 100% or not, and being able to keep all of your technical support with the same installer and manufacturer. But so long as you can communicate with these panels over
DMX or another
protocol, it's debatable how much value
ETC's brand name has for panelboards that no one will look twice at until they're replaced in 30-40 years.
So you can look at this two ways:
1) Do you
need relay control for modern
LED systems, versus leaving these circuits energized 24/7?
2) If the answer above is "Yes", do you subsequently
need a
relay panel specifically made by a theater lighting manufacturer.
In my mind, the answer to #1 -- it generally protects your investment, reducing the energized time of
power supplies and reducing dust intake on fixtures with fan cooling. Will your
system blow up in a blaze of glory if you don't have it though? No, but you may end up having to replace/repair fixtures sooner -- and you'll need to give a lot of cleaning love to any fixtures with fan cooling, provided those fans are not thermostatically controlled to only engage when the
fixture is actually in use.
As for #2 -- no, there is little compelling reason for the
relay panel to be theater-specific beyond that it's easier to specify and deal with for any potential support issues. If you're getting a
system from someone like Eaton, your theatrical vendor may not have a support relationship with them -- but your average electrician is far more likely to know what they're walking up to -- so there is a tradeoff. The controller may not natively support
DMX but there will certainly be a
widget available that can interface it. Since modern buildings have
LCP's building or campus-wide, integration with a broader lighting control
system may also be just a little
bit easier. Personally I don't know where the pricing falls if there's any compelling reason to go one way or the other, but certainly it is not like
ETC is the only company making
relay panelboards.
Footnote: Most of my work is new construction so I mostly care about
relay panelboards -- not
dimmer racks with
relay or ThruPower modules. I would not specify an actual dimming rack with
relay or ThruPower modules in this day and age unless it was a professional roadhouse that had a greater risk of encountering
tungsten fixtures.