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we had a couple brief power outages during a show last week. It's not that big of a deal, just a hussle upstairs to restart the film (usually in the dark). It got me to thinking, though, is this bad for my equipment or the film? It's not like I can do much about it, but I want to be sure if there is something special that needs to be done.

It's not likely to damage your film as all the equipment (projector/platters) shut down at the same time. There may be a slight chance that a power surge could damage you sound system and computers. But I would hope the manufacturer built some sort of protection into the sound equipment and that you have your computers plugged into a surge protector.


At our ten-plex when we have a power outage we have to re-start all the projectors and sound systems plus the terminal computers at concessions and in the boxoffice. If we can't get the terminals going we call corporate "Help Desk" and they turn them on from their end. Obviously this takes several minutes even after a 10 second outage. I'm not sure I would run a theatre with all this electronic equipment.

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Bob Allen
The Old Showman
"Back In The Saddle Again"

It's not so much the outage, but rather the irregular power spikes or low voltage ("brownout") that sometimes happens too. Generally, it is wise to provide a UPS (Uninterruptable Power Supply) for all the digital equipment, including sound processors, digital automation, computers, etc., so they won't see the "spikes" and can be shut down "gracefully" if the outage persists. The surge protection that a UPS affords also helps protect against adverse effects from a lightning strike on the power lines.

You should also invest in emergency lighting. It is certainly required for the public areas that may need evacuation, but also should be in the theatre "control center" which is often the booth.

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John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Cell: +1 585-781-4036 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion

Well, I use UPS systems for my computers but I haven't been using them for the sound equipment. That's probably a good idea. I was wondering about the poor film. The frames that are in the gate when the outage occurs might get pretty toasty. Should I hussle up there and try and get them out of the gate quick?

I have emergency lighting in the auditorium of course. Half aimed at the screen and half aimed at the door. This serves to light up the whole room rather nicely. I don't have anything in the booth but those darn things are pretty expensive. I just use my trusty flashlight....

[This message has been edited by leeler (edited January 11, 2005).]

Power outages are bad news for your Xenon bulb... Normally, they require a cooldown period after they are turned off, during which the exhaust blower continues to run... Back in the early days of Xenon I was working in a theater which had a power failure, and an hour after we had power restored the practically new Xenon bulb blew from the loss of cooldown... A very expensive experience!...

You should have a failsafe on your projector so it won't just restart when power is restored, and the voltage spike protection is a must for any sensitive electronics...

John's mention of emergency lighting is also very pertinent... Even if emergency lighting isn't required by your local codes, it is still a must have... If you've ever experienced a power blackout with a house full of customers you already know what a nightmare it can be without emergency lighting...

Well, everything is tied in to an automation unit so when power is restored I just hit the button to get it running again. If the power were to flicker or come on and off a few times it would NOT turn the projector/platter on and off. However, the fan, of course, also loses power so the heat from the bulb is not actively cooled for that time period. I don't expect there is anything much to be done about that, though.

I have sufficient emergency lighting for the customers in the lobby and the auditorium, just none in the booth.

[This message has been edited by leeler (edited January 11, 2005).]

"The frames that are in the gate when the outage occurs might get pretty toasty. Should I hussle up there and try and get them out of the gate quick?"

It's usually the radiant energy of the lamp that causes heat damage to the film. So with a power outage, the lamp is already off and cooling as the projector coasts to a stop. Although contact with the hot metal components of the gate are unlikely to burn the film, upon startup, you may find the film will want to "stick" in the gate, so it's probably a good idea to run the projector down by hand and check to be sure the film is not sticking. Also, check to be sure the outage did not throw some slack into the film path, which could cause it to jump a roller, pick up dirt from the floor, or jerk to a start, tearing some perfs.

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John P. Pytlak, Senior Technical Specialist
Customer Technical Services
Entertainment Imaging
Research Labs, Building 69, Room 7525A
Eastman Kodak Company
Rochester, NY 14650-1922
Telephone: +1 585-477-5325 Cell: +1 585-781-4036 Fax: +1 585-722-7243
E-Mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Website: http://www.kodak.com/go/motion

With most indoor installations, the most obvious equipment to check will probably be the platter, since most booths won't have backup power sources for anything.

Depending on what kind of projector you have, it would be wise to check the position of your platter's control elevator. If the soundhead is a Century model, it's likely the machine won't have trailed out enough film to drop the elevator all the way, leading to possible damage when the power returns & the takeup platter overtorques (mainly on Strong platters). If you use a soundhead with a couterbalanced motor, you MIGHT not have this problem, though you might drop some film on the floor.

Xenons probably don't like being shut down without cooling, and I never do so intentionally. However, I've been in numerous booths in the last 30 years that have lost power without any obvious ill effects to the bulb. In any case, if you don't have any backup ventillation scenareo, it doesn't matter much. just don't open the lamphouse!

I'm in the middle of a major booth rewiring at my drive-in. With the installation of digital sound equipment, I'm centralizing most of my electronics. The new racks are built into a wall, and contain battery backup for the radio transmitters, microphone circuitry and (at least for a couple of minutes) the lamphouse fans. This gives me the ability to let my customers know what's going on while I get our backup generator in place & switched on. For an indoor house, at least consider emergency lights and (especially in multiplexes) some form of emergency PA system to keep your customers advised. In most cases, the emergency lights are required anyway, but if not, they're an obvious benefit and available at any Lowes or Home Depot.

My latest (January 2005) Heartland America catalog (www.heartlandamerica.com) has a complete ready-to-go double headed emergency light unit (item # C1-98674) for only $16.99! That would be perfect to put in your projection booth.

Emergency lighting should turn on automatically in ALL public areas, and also in many 'private' areas as well, if one intends upon operating practically and safely during an outage. After all, with today's stressed and aging power lines, prolonged outages like those of last summer, are bound to reoccur. A UPS (uninteruptable power supply) is vitally needed for any electronics, including Public Address and security systems, but it is probably quite unaffordable for most projection. Still, it would be nice to be retrofit the fans in the projector to operate through a start relay on a DC battery supply set to kick in when the AC fails. This may be difficult to install for most of us, especially if the machines are still under warranty, but one thing we can do is have an electrician install a Safety Interrupt contactor (power relay) with a push-to-start button on the outside of its box and then hold through one of the poles (contacts) and wired into the AC line such that the relay drops out (disconnects) when the power fails so that repeated spikes and surges are not encountered when the power tries to reestablish itself after a momentary outage(s). You would have to go and manually push the 'On' button after you believe that the power has returned for good. Power company lines are breakered with devices that try to reconnect the power automatically for up to three times if they detect an outage, and these restart surges are very damaging to motors and electronics. Sometimes commercial versions of AC power protectors also have Brown-Out detectors that will shut down the AC when the voltage drops too low, which is especially damaging to large motors. The W.W. Grainger catalog used to carry such devices; call their local outlet for help, or an electrical supply house.

There is an ongoing thread on Film Tech about the adverse effect that a power failure (and loss of xenon Lamp blower cooldown period) has on Xenon bulbs... The latest post on the subject is from a Xenon bulb manufacturer, and he concludes that the 2,000 degree electrode operating temperature does indeed subject the quartz envelope (and seals) to far more than the 700 degrees they were designed for in the event of a power failure that interupts the cooldown period, and could cause either immediate failure on re-strike or significantly shorten the bulb's lifespan... That re-inforces the bad experience I had back in 1968...

All bulb manufacturer's state a min of 10min forced cool down

In my comments above about using an Uninterruptable Power Supply, I should have made clear that most of those sold for computer use are not necessarily workable for projector fans and other motorized devices. Such power supplies do not supply the pure sine waveform of the 60hz AC that goes into our buildings, but APPROXIMATE that needed waveform with a stepped waveform that is NOT the desired sinusoidal shape as seen on an oscilliscope. For this reason, note and follow the warnings on UPS power supplies that you are considering. For example, merely wiring such a converted battery supply from or for emergency lights will not necessarily work for electronics, or motors (fans). It is vital that the supply be matched to its load, as is in all electircal code law. Of course, if you are sure that your projector's fans are straight DC, then you can build a switchover that would deliver battery power which is always DC, at the appropriate voltage, of course. Beyond this, it is probably best to consult an electronics technician or electrician as how big a standby generator (actually, an alternator) that you might hook into SELECTED building circuits since such high power and higher priced power supplies do deliver a waveform more accurately sinsuoidal than do electronic converters for small scale use as for a home computer. Thus such can power motors and fans within the rated load of the supply.