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Its VERY intrresting when the Power Co. loses a Leg, its happened to me twice. Fortunatly at the building I was at, the A/C compressors had protection circuitry to protect them from such a thing. However the elevator electronics did not fare so well, trapping of all people, the electrician, as we desperately searched for the main switch to the building. (this was in a new theatre before the grand opening)

Do any theatres have permanently installed voltmeters (or at least indicator lights) at the main panel to indicate that all legs of the 3-phase power are present, and whether they are balanced?

My home is on a hill in a lightning-prone area (in 15 years, about 10% of the homes have had direct hits). When we had lightning rods installed on our roof, we also installed surge protectors in the main 200A electrical panel. Much of the lightning damage in our neighborhood came in through the power lines -- one neighbor had every electronic appliance in his house damaged when lightning hit an outdoor light.

IMHO, operating sensitive digital electronics without proper surge protection and UPS units is asking for trouble.

But beware (not of the above comment) some of the older buildings may have 3 phase closed delta. That type of power has a "wild leg" which is worthless to 115vac applications. If I recall correctly, that leg is about 177vac, referenced to ground. It is not normally used with anything except 3 phase motors. If you lost it, you would never know until it is too late.

It is best you do some research on what type of power you have, so you can act accordingly when an outage hits. If you have a power poll feeding your building, look at the transformer configuration.

If there are two small "pots" and one big "pot", (as the power company calls them) you probably have 3 phase closed delta. This type of configuration is obsolete. However, it is still around and you will find it in old buildings.

If you have 3 "Pots" all of the same size, more than likely have 3 phase open delta. This configuration is used in all new commercial construction these days, unless your area is still living back in the stone age.

Residential power is usually single phase. I have never seen or heard of three phase power being used in the average modest home.

There have probably been exceptions, but we're also in a very lightning-prone area, & after making that discovery, the little cheapo UPS's are everywhere. Stick them upstream of the stuff in the soundrack & the platters. Lightning strike, splat goes the UPS, go get another one, OR: spend way too much time trying to figure out what's now acting flakey & intermittent after the strike.

The funny thing is, none of the 'phone lines are carried on overhead pilons in my neighbourhood - they're all underground. So I've no idea how the lightning got into the system.

Lighting doesn't "see" the ground as a solid object. The large electron clouds and positive charged areas seek ways that they can connect and equalize charges. Sandy soils that are relatively dry don't act as good conductors, nor is any earth a consistant conductor. (Sea water, OTOH, is an even conductor.)

A phone line buried in the ground isn't really protected from lightning, since bolts of lighting will actually burrow through the ground to get to an area containing a charge. One result of this and proof of the effect is a fused tube of dirt and sand called a fulgurite.

True protection from power line and phone line surges requires a single point bonded ground system at the main electrical, phone, and cable tv entrance, and surge protection at that point. The ground has to meet specifications that many home ground systems do not attain.

Using small UPS units or surge protectors can actually create problems if not properly handled. Example: Your computer is on a UPS and you think it totally protects the computer. The instructions on the UPS say not to plug a laser printer into the UPS and it only has two sockets anyway, one for the computer and one for the monitor. You plug the laser printer into a wall socket or cheapie surge protector.

When a big surge occurs, the cheapie surge protector blows the MOV inside, leaving you with no protection on the laser printer. The next surge finds a path through the laser printer, through the printer cable, and into your computer.

Network cards are designed with some surge protection, and the coils in a modem choke out some surge before they self destruct, but any large surge or near strike can take out equipment.

Even if the equipment isn't destroyed otright, and seems to work afterword, the components have often been stressed by the overvoltage and some may fail within a short period of time or operate outside of normal values, which can lead to a computer acting "funky" but seeming to work most of the time.

There are lightning prevention systems and lighting protection systems available, but the installer has to know exactly what he is doing and why to make them effective. Lighting can use such things as linoleum as a conductor, and can refuse to make sharp turns on a large conductor, preferring instead to arc to a more straight-line path and smaller conductor. This "no sharp turns" effect has given rise to the highly questionable practice of tying "choke" knots in power cords as a method of surge suppression. The idea has merit when a toroidal coil is designed to tune out surges, but knotting a power cord is an unreliable method of protection.

The simplest and most reliable protection for electronic equipment during a storm is to unplug it from all external wires. Short of that, computers and equipment should be powered by a single source that is properly grounded, and kept in a very tight configuration, where no ground loops can occur. A surge strip can be more helpful as a single plug to unplug than as a protected power source.

The area where I live has incredible storms. A few years ago conditions were right, and there were storms where there were literally as many as ten lightning strikes in the immediate area per minute, for periods up to twenty minutes at a time. At least once or twice a summer we are treated to a light show of "boiling" lightning, where a distant storm or two will have clouds nearly constantly lit by lightning. Watching two distinct and seperate storms, I've seen them interact electrically where a discharge in one storm will be followed by a discharge in the other a few seconds later.

Lightning in Florida is better than most movies.

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The funny thing is, none of the 'phone lines are carried on overhead pilons in my neighbourhood - they're all underground. So I've no idea how the lightning got into the system.

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Much major damage from lightning is from induced voltages, not direct "connection" to the lightning. Paul has probably seen all the humorous aerial photos of AM radio tower sites after a lightning storm where the induced voltages in the underground radials draw fried brown designs in the earth.

One of the main reasons that almost all network cabling now is twisted pair instead of coax is that twisted pair is less prone to induced voltages.

Leo's right about phone lines, though. If it gets into the phone lines (yes, they're usually twisted pair, but it happens) & then to a computer or automation interface, off it goes as a direct strike through the network, any audio, & AC lines. Phone lines need serious isolation & lightning protection.

This topic is in the Ground Level forum!
BWA-Ha-Ha-Ha!

Okay, joke's over.

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William, I argued this for quite a while, but was eventually shown it just isn't technically correct. Damage occurs from ground loops where there is a voltage differential, and from direct hit on a line and resultant surge, and from slower discharges that don't always generate a lightning bolt, but very rarely from voltages caused by induction. The short time span involved and the "de-tuned" nature of the beast dictates that very little induction occurs except in very rare cases, and the amperage of the induction is usually insignificant. The only semi-documented case of damage by induction I could find was a report of a high-tech x-ray machine that had been damaged even though it was totally unplugged. Even here, there was a question whether a charge had propagated across the surface of the floor.

What does occur is an entire area will become charged and parts of the area where ground leaders occur may have a greater potential than adjacent areas. Even though a "failed" ground leader isn't the primary discharge path, it can still be discharging some local currents. A leader doesn't even have to glow to exist and be moving electricity, and I *suspect* a full blown lightning strike may not have to occur to damage particularly sensitive equipment. A lot of what gets described as "induced current" damage is much more likely damage from secondary or failed leaders.

Bringing it back closer to topic, most newer theatres are protected from effects like this by the metal roof decking and drier air in the building. Charges go up the rebar or gutters and bypass the interior spaces.

Burn marks around radials can occur for a number of reasons. My dad was C.E. for an A.M. station with 3 free-standing 500 ft sticks. The towers were regularly discharging during storms as well as getting hit. The spark gaps between the paired volleyball sized electrodes would light up the ground at night, making them clearly visible from the transmitter building. The radials collected (or dissipated depending on your preference of terminology) all that energy.

Your first priority, as John P. pointed out, is audience safety. Following is the list of things, in order, of what I would do/have done in the case of a power outage:

1) Instruct your projectionists to follow your set emergency procedures (you do have one, don't you?). This should include shuting down breakers, etc as has been noted in this thread. You can also have them check to make sure none of the electrical panels got shut down accidently thus causing the outage (a good thing to do before you get to involved in taking care of the situation). The projectionists should be responsible for shutting down all breakers in the building, not just the ones in the booth. Your ushers will have enough to do without worrying about that.

2) Your ushers should handle the patrons, assign concession people to help if nescessary. One person should be posted in each corridor, informing patrons who are spilling out to please remain in their seats while theatre management contacts the power company about the temporary power outage. Make sure the employees inform the customers that the power could come back on at any time, and when it does their movies will start exactly where they left off. While these employees watch each corridor, send the remaining ushers to each auditorium where they will make a similar announcement.

3) Make sure your cashiers are informing people similarily, that the outage may only last a few minutes and as soon as the power is back on they can purchase tickets.

4) You, as the manager, will have to make two very important phone calls. Remember that your phone systems central panel runs on electricity, so it won't work. You'll have use the payphone in your theatre. If your theatre doesn't have a payphone, get one! But in the meantime, you'll have to go somewhere that does have one or a regular phone you can use. First call the power company and infrom them of the outage (they don't automaticaly know, you have to call and tell them). Then call your District Manager or City Manager, whoever it is who is directly above you. Inform them of the situation and the steps you've taken. This isn't meant to be a sign of weakness/call for help, it just informing your superior of a situation they should be aware of. Usually they'll say fine or "keep me informed." If they do, you know your doing your job ok so far.

Now it becomes a wait and see game. What the power company tells you (if you talk to a real person that is) will determine where you go from here. While you are waiting, remember your concession stand can still be open (that is if the cash drawers aren't locked until a sale is rung up). You won't be able to sell pop, but you can sell the popcorn remaining in the bin, candy, nachos (as long as the cheese stays warm), bottled water, pretzels (as long as they stay warm), etc. Just have your concession attendants record all sales on a piece of paper in their drawer so they can be rung up after the power comes back on.

Security will be an important issue, since your security cameras wont' be working. If you think its nescessary, post a guard at the office door to watch over the safe. Take all box office drawers to the safe, you won't need them until the power comes back on anyway.

Do not keep your patrons waiting in the auditoriums anymore than half an hour. Not only will they get irritated, but safety becomes an issue. Emergency lights don't last forever. You DO NOT want patrons still in the theatre when the emergency lights start going out. After half an hour or less (your descretion), have your ushers make the rounds of the theatres again, this time giveing the "We are very sorry..." speech. Tell the patrons that their tickets stubs (which should have the date and time on them) will be their rainchecks, and will get them into any show, any time afterwards. You may wish to put a time limit on this, say two or three months. If your theatre is really full, you may want to stager the auditorium announcements, but remember, time is off the essence, get them out before the lights go out! Now this part is very important, DO NOT GIVE CASH REFUNDS UNLESS IT IS ABSOLUTELY NESCESSARY! Some people may disagree with me here, but this is a business, and giving out $4,000 in cash after an outage just doesn't make any sense. If someone is adament about getting their money back, return the dough discreetly, out of view of the other customers to prevent a mad rush to get their money back.

Now that your patrons have exited (if they did), your going to have to do something about the film. If you wait until the next set to rewind it, your going to lose a whole set of shows, you can't very well sell tickets to movies that are half over (if this is the case). If a movie is only in the previews, or even half way through the first reel, you can probably cut it and drop it back in the roll. I wouldn't attempt this if the movie is more than halfway through the first reel though. The following procedure is for the movies more than halfway through the first reel. It is risky and should only be attempted if you are confortable around film. Get together your projectionists, managers (leaving one to watch over the floor), and any ushers you think are responsible enough to handle this. Make sure each print is suction cupped/beaven pooed down securely. Unload the projection, leaving the film on all rollers except the lower magazine roller. It should look like your about to thread buttom up. Now, making sure the film is securely in place, spin the platters through by hand. You can probably do two or three at once, making sure the film is on all rollers, etc so it does not get damaged. You should be able to spin the film through at two to four times speed without any danger of damage. Some here may disagree with this, but it beats running your movies through to empty screens just to rewind them. I've had to do it several times, and have never had any problems.

Once your film has been rewound and the patrons exited, your job becomes boring again. You have to wait around until the power comes back on. At some point, your going to have to make a decision of whether or not to just close for the day. This decision should only be made after speaking with the power company and your immediate superior. Have your staff clean up as best they can, keeping in mind there won't be any water pressure and probably no lights. You'll have to come in later on when the powers comes back on to close out the computer, ring up the concessions sold during the outage, punch out employees, etc.

Thanks for your lengthy post and taking the time to respond. Terriffic! You covered a lot of ground (no pun intended) and this was what I had hoped would come out of this thread.

Many of our procedures are similar, but there are some additional things you mentioned that we can definitely use.

I agree that projectionists should shut down breakers in the booths, but in our situation they would be unable to get all the breakers downstairs due to the fact that we have a number of pannels spread over a wide area, so we assign that aspect to the head usher.

We feel cash refunds are big trouble in these situations, so we offer unrestricted passes, no exceptions.

I remember when it just took a strip of masking tape with arrows next to the right breakers to get the place shut down. Now, we had to (finally) install stoppers on the breakers that have to be left on!