I haven't seen that DJ-A,

But like you say that's what the rumor mill says. So me, I can neither confirm nor deny.

It really depends on the type of fog machine.

that's interesting... please, tell us more... what kind of fog will and will not effect the sprinkler system?

WRONG. EVERY fog machine and hazer has the POTENTIAL to set off the fire alarm.

The question is what type of sensors are they using and are they impacted by fog?

There are some fire alarm sensors used to detect smoke that determine the particulate in the air. Fog will set these machines off quite easily.

Hazers have a much lower rate of occurance but they WILL set them off as well.

In the end, any time I use fog or a hazer I talk to the maintenance guy at the venue who is in charge of the fire alarm and the manager of the venue, and even if I'm cleared to use it I'll still stop in at the local fire department and let them know that I'll be performing and have written permission to use fog/haze.

If you DO use fog/haze be sure to get written permission that prevents you from being held liable for the cost of the fire department being called out for the alarm if it does go off. Some places have to pay a fine for false alarms - particularly if they go over a certain number of alarms per year.

Best bet? Don't use fog/haze. If you do have to use it then get written permission/waiver.

"The particles produced by fog machines will set off ionisation type smoke detectors. Generally this is only a problem with ionisation or optical type detectors as they sense the fog particles as smoke. It is therefore wise to check that the use of fog or haze is acceptable by venue management and that their fire alarm system is compatible with them. You should never attempt to disable smoke detectors by gaffa taping them up or unplugging them from their sockets as this would be a foolish and dangerous route to take resulting in serious litigation by the authorities if you are caught or there really is a fire. Sprinkler systems are usually triggered by heat therefore fog will not active these."

Some very informative reading. Let me be the first to say thanks guys ;-)

Yep, read what sixxx posted... you don't usually have to worry about sprinklers going off, but you DO have to worry about the smoke alarm calling the fire department and the resulting fines.

most people that set off spinkler's ect. have been known to use oil based fog fluid. make sure you use water based fog fluid and you should'nt have problems.

I dont know of any foggers that will set off sprinklers.... 95% of sprinklers require HEAT to make them set off.... now as for the fire alarm... YES foggers and hazers will both set of the alarms in some places.... but hazers typicaly dont set them off as often as foggers. BUT just b/c the alarm goes off does not mean the sprinklers will go off..... all the srinkler systems i know of (and have worked with) have a part in the sprinkler head that when moved makes the sprinkler go off.... that piece is moved by being heated (making it expand or melt depending on what its made of) or being knocked out (wich causes a mess for no reason..... and has flooded many department stores b/c of stupid employees)

my bad "typo" on the sprinkler part. yes dj disturbed your 100% correct. about heat setting off sprinklers. what i should have wrote was oil based fluid is the main reason fire alarms are set off.

ohhh I forgot... some use glass parts to make them go off.... but it still works like i said.... the glass heats up causingthe tiny bit of fluid inside to heat up and expand... the glass breaks and you get a down pour..... but it still take heat to do this.. and more heat then the fogger produces

Yep, the sprinklers aren't normally the problem (you can also hit the sprinkler heads, breaking the glass and cause them to go off).

It's the fire alarm. Imagine this.....

You're jamming a wedding, having a BLAST, and the party is getting WILD. You hit the fog button filling the dance floor and everyone goes crazy.... until the fire alarm goes off.

Everyone goes outside and wait for the fire department.

The fire department reviews the scene declaring it safe for everyone to return to the building an hour later. They pull the venue owner/manager aside and write them a big fat ticket for a false alarm. The venue manager hands you the ticket saying that they expect you to take care of this because it was your fog that set off the alarm.

In the meantime the guests are packing up and leaving. The bride tells you she wants a refund because it was your fault the day was ruined.

Here's my recommendation....

1. Get permission to use a fog/hazer.
2. Notify the fire department that you will be using a fogger/hazer at that venue and you have written permission to do so.

The smoke alarms look for particulate in the air. Any fogger/hazer can set them off if you're not careful - even with a water based fluid. I've seen the ugly side of fog/hazer use... and it's why I generally don't use them for indoor events.

Well, that and most of the shows I'm doing now don't use lights. In most cases, I would only use haze/fog to make the lights show up better.

In the end... just plan, get permission, and be careful.

here's a funny sprinkler story. mr friend (Dan) was at a chicks house, he went to take a shower and thought the sprinkler on the ceiling would be a good place (her apt had them in all the rooms)

to make a long story short, nothing happened, he takes a shower, turns the water off and water kept comming down... while he was in the shower the hanger shifted breaking the thing in the middle. not only was the sprinkler going off but he came out in a towel just in time to have the fire dept show up...

this is interesting. nice tip mm!