Well, this just goes to show you why seeking out someone that understands electricity, lighting, AND theatre is important when doing lighting upgrades. I'd be happy to chat with you and/or your maintenance staff / administration about this. Here's what has been misunderstood:
LED lamps are NOT like incandescent lamps in the way they can be dimmed.
- Incandescent lamps just glow at different brightness levels depending upon how much power is delivered to them. They fade smoothly from one brightness level to another because the filament in the lamp gets hotter or colder.
- LEDs operate on a completely different basis. They have two parts: The LED that glows, and the internal power supply / dimmer that adjusts the current to the LED element to vary the brightness. This is where the problem occurs -- when your theatrical dimmers reduce the voltage to the power supply inside the LED lamps, they are supposed to detect that and then reduce the current delivered to the LED. As the theatrical dimmer voltage drops into the lower dimming range, the power supply inside the LED lamp gets starved for operating power, so it gets confused and struggles to operate. This messes-up the circuit that is supposed to detect the incoming voltage and translate that to an outgoing current. The result is LED lamps that flicker and blink-off at unpredictable levels. ALL LED lamps do this to a certain degree. No of them operate perfectly.
- Incandescent lamps rely upon the heat of the filament to make the filament glow, therefore, lamp sockets are specifically designed to isolate the lamp heat from the light fixture housing. LEDs MUST have a way to shed the heat from the power supply / dimmer and the LED chips, therefore, when you screw an LED lamp into a incandescent fixture socket, there is nowhere for the heat to flow to, so the LED lamp ends-up with a relatively shorter life expectancy. One of the key reasons for upgrading to LED lights is to eliminate the frequent trips the maintenance department has to make up a ladder to change the bulb. The energy savings is actually minor compared to the labor savings on maintenance. A good quality LED house light fixture will last 15-20 years without maintenance, and by that time we'll all have some newfangled technology and your auditorium will be due for another major renovation.
The correct way to dim house lights (and stage lights) when you transition to LED type lights is to REPLACE THE ENTIRE FIXTURE. You have to run a constant line voltage to the fixtures (so the power supply inside can operate properly) AND a control wire so you can tell the power supply to vary the current going to the LED.
There are numerous ways to do this by way of 0-10 volt DC control signals, DALI control signals, and DMX control signals (the same DMX used to control LED stage lights and your existing dimmer rack). There are a lot of reasons to use DMX control and not 0-10V or DALI. For one thing, it is a native control format that your existing dimming system understands, and another is that it provides explicit control of the lamp brightness with 16 bits of accuracy (4096 steps from OFF to FULL ON). Also, it has the ability to use light fixtures that can be individually addressed. This allows setting brightness by the row, or even individually. This is very helpful when the elevation from the floor to the ceiling is different as you move from the front row to the back row, or under a balcony. You can make the illumination of the room very even with a little planning and careful set-up; and if you have a need for special effects over the audience, you can set-up cue sequences that might allow you, for example, to have a flying saucer fly from the stage across the audience and disappear (think; the end of 'The Foreigner').
When LED fixtures replace the existing incandescent fixtures, you have the opportunity to increase the brightness of the overall illumination. Many auditoriums are too dimly lit for using the tablet arms for classroom / testing functions, and really don't have enough brightness to facilitate the janitorial staff's cleaning properly. Seize this opportunity to correct the illumination levels if this is needed.
Changing-over to LEDs for either house lights or stage lights involves installing a DMX distribution system, usually with separate DMX universes for the house and stage control zones, and adding / reprogramming a master controller so managing all of those control zones is simple for the casual user. This is an opportunity to have proper light control stations installed beside all of the auditorium doors so it doesn't matter where someone enters or leaves from; and to add some automation functions so the lighting system will not allow the operator to leave people in total darkness until everyone has had time to exit the space (a very real safety issue), automatically meet the NFPA fire code illumination minimums in each area (yes, you cannot have blackouts anymore), can automatically dim the lights off if they are accidentally left on after hours, can automatically leave a few 'special' lights on to illuminate the stage apron so someone doesn't fall off the stage in the dark (automatic ghost lights), etc.
Upgrades of the lights need special considerations with regard to off-axis spill (glare in the audience's eyes), color temperature, color quality, linearity of dimming, emergency power, and emergency control. Most electrical engineers 'no hablé theatre', so they will likely choose incorrect fixtures if given the opportunity. Upgrades to houselights have to carefully integrate the aisle illumination, but it doesn't necessarily have to come from lamps in the ends of the seat standards. Maybe retrofitting those so they can be reused is appropriate, or maybe a alternative should be installed -- it varies for every situation. The NFPA has strict guidelines about the illumination cast upon the aisle-ways (and the control of that), so that has to be achieved in a compliant manner.
The rerouting of the light fixture power away from the existing dimmer rack and to new automated circuit breaker panels also requires some finesse that is rarely understood by electrical engineers. It is a 'lighting system' -- not just a bunch of light fixtures.
Upgrades and/or additions to the backstage work lights, backstage Run-of-Show (ROS) lights (running blues, discrete so no spill to the audience), for areas like fly galleries, gridiron decks, shops, dressing rooms, and other color critical work spaces should be considered. Most facilities are poorly illuminated with low levels of light for task intensive operations that require proper color temperature and color quality for selecting paint and fabric colors, sewing, make-up application, scenery construction, etc. This is particularly true over the stage as most stage have black walls, black floors, and black masking drapes; so stage work lights need to be really bright without burning through conventional incandescent stage lighting lamps (how many times have you found the stage lights left on because someone needed more work light?).
Also, like the house lights, consideration should be given to proper control stations for work lights and ROS lights all around the backstage areas. No one should have to walk in the dark to find a light switch, or climb a ladder in the dark to turn on/off a light. The Stage Manager's Workstation should have complete control of all of the work, house, and run-of show lights in addition to the local control stations. No one should have to work in the dark backstage during a show.
We have the technology to solve these problems in an ergonomic and energy efficient manner that almost completely eliminates maintenance. LED lighting systems are a whole new game, and it requires a significant learning curve to get it right. When facilities get updated, you are sometimes stuck with the mistakes for a very long time, so it is much better to get a clear plan of what is truly needed and get it right the first time (or, in your case, the third time). The Devil is in the details.
------------------------------
Erich Friend
Theatre Consultant
Teqniqal Systems LLC
------------------------------
Original Message:
Sent: 04-14-2022 09:40
From: James Fewer
Subject: LED house lights
Our district, in its infinite wisdom, decided to upgrade our house wall and chair lights to LEDs. I love the idea. But problems 1) won't dim! Despite their argument they put in dimmable lamps. (Dimmer lowers to 20% no change . 19% out completely - how is this dimmable? ). 2) hired an electrician and completely removed seating lights in the house system from control by console. (Reason was it was a way to do what we needed without changing our rack.)
Anyone have experience with this and how to seek proper repair ??
Sent from my iPhone