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Fog machine- fire alarm help

  • 1.  Fog machine- fire alarm help

    Posted 03-01-2017 05:25
    We spent a lot of money renting a good quality fog machine for our show The Little Mermaid. The first two weeks we practiced with it, no problems. Now we are setting off the fire alarms. Trying to work things out w putting it on test, but admin is not happy. Uhg. Anyone have any tips to prevent fire/smoke alarms. We had new roof put in over summer and they switch from heat sensor fire alarms to smoke alarms. This is why we are having this problem for the first time.

    Sent from my iPhone

  • 2.  RE: Fog machine- fire alarm help

    Posted 03-01-2017 11:29
    I'm getting this information second hand, so I may be wrong on this, but before I started at my school, they had a similar problem. They were using a fog machine for Les Mis, and it kept setting off the fire alarm too. I *think* what they ended up having to do was disable the alarm, but pay to have the fire marshal on site for whenever they did that. At least I think that was what I was told.

    Christopher Hamilton
    Drama Teacher
    Kennewick WA

  • 3.  RE: Fog machine- fire alarm help

    Posted 03-02-2017 07:11
    In our school system, some schools set off the alarm.  In this case, a trained person from school plant puts the alarm in a different mode - but is paid by the production to stay on site  & be in contact with the fire department.

    Tammy Smith
    Virginia Beach VA

  • 4.  RE: Fog machine- fire alarm help

    Posted 03-02-2017 13:04
    You may want to try using a low lying fog solution or drying a fog machine that has a place for dry ice to cool the solution and keep it more on the ground. 

    Mrs. Dana Leach
    (562) 889-2406 cell

  • 5.  RE: Fog machine- fire alarm help

    Posted 03-02-2017 14:07

    Sorry to be the bearer of bad news, but this issue is coming up more and more in the newly constructed high school theatres that I’m working in, and administrators aren’t that keen on shutting down the smoke detectors (or putting them in test mode) for plays. In the last 3 theatres I managed we simply had a No Fog Machine policy.

    All is not lost though – we did allow ground fog (mostly dry ice). You can find a suggestion for policy wording in my High School Theatre Safety Manual, but in short, here it is (feel free to appropriate):


    Fog Machine Policy

    Most smoke detectors are designed to measure particles in the air and risk being set off if the smoke level from a fog machine gets too high on stage. Therefore smoke machines and hazers are not permitted in the theatre.

    Dry ice and ground fog may be safe as they tend to gravitate downwards, but if you chose to use dry ice and/or ground fog, you do so at your show’s own peril. If they set off the fire alarm, the theatre must be completely evacuated (performers, crew, staff and audience), and permission must be given by the Fire Department before anyone can re-enter the building. In that case, your show will most likely be shut down for the remainder of that performance. 

    _____________________________________________        ____________________
    Signature of User Representative                                         Date

    • Indicates that this notice has been read and that User accepts all risks.

    Beth Rand

    High School Theatre Management Coach

    Next HS Theatre Management online course starts March 27 - spaces still available.
    Author of "High School Theatre Operations" and "High School Theatre Safety Manual"
    Woodinville, WA

  • 6.  RE: Fog machine- fire alarm help

    Posted 03-03-2017 08:01
    Like most people have said. i run into this a lot. The thing that I have been able to use the most and not set off the alarms are Haze Machines. The particles are much more spread out than I fog machine. I have run a haze machine pretty strongly during a few shows and never had a problem and I monitored the numerous particle counters in the room and it raised but not enough to cause a problem. I now work in a school that I still need to figure out, and we are in Rhode Island which because of the night club fire have some of the most strict fire policies I have seen.  

    We are talking Jeckyl and Hyde next year and I want fog or haze! lol. Not to mention we run a haunted house every year and whats that without that element!

    Dan Mellitz
    Technical Director
    St Andrews School
    Barrington, RI

  • 7.  RE: Fog machine- fire alarm help

    Posted 03-03-2017 13:07
      |   view attached
    Agree. Go with haze. I also recommend using two, versus one, for an even spread.

    Garry Tiller
    Theatre Arts Teaching Artist
    Hawaii Independent Schools
    Honolulu, HI

  • 8.  RE: Fog machine- fire alarm help

    Posted 09-02-2019 15:05
    Hi Dan -

    I'm in Wakefield, RI and since the Station Fire - my school/town has had a no haze/no fog policy.  I notice that the policy has been shifting in other parts of RI.  Do you know if rules changed or if people have just started using them again?  I'm doing Matilda (want haze) and Brigadoon (want fog) so I'm trying to get some research to back up my request for my school and local fire department personnel.  Any information would be most appreciated!

    Vivian Humphrey
    Wakefield RI

  • 9.  RE: Fog machine- fire alarm help

    Posted 03-03-2017 14:34

    You may want to have a conversation with the administration / construction department about the installation of the smoke detectors.  The NFPA has shifted to requiring Rate-Of-Rise Heat Detectors over stages for the very reason you have described (smoke detectors false tripping).  Specifically, if you have a Fire Curtain it is to be tripped (released) by the detection of a thermal gradient from a Rate-of Rise Heat Detector (not from a smoke detector).  The alarm system installer should have known this, but like many other things, they just aren't aware of the special circumstances of a theatre.

    If they are just dead-set on detecting smoke, then a good option is to have the smoke detectors replaced with a "multi-criteria" type detector similar to the ones manufactured by System Sensor company (  They have a combination of Smoke Detection, Rate-of-Rise Heat Detection, and (optionally) CO2 Detection.  The detector won't signal an alarm condition until it registers a condition on both parts of the detector device, thus preventing false trips (

    If your system has smoke detectors in air ducts that draw air from the stage, the in-duct sensors sometimes false trip on atmospheric effects.  One way to thwart this problem is to shut-down the air handler temporarily during the part of the show where the atmospherics are used, and then restart the air handlers after the effects have had a chance to dissipate.  This approach also keeps the atmospheric effect on the stage rather than having it sucked / blown away.

    Erich Friend
    Theatre Consultant
    Teqniqal Systems

  • 10.  RE: Fog machine- fire alarm help

    Posted 09-03-2019 10:55
    Yikes. Had this happen during Joseph. Make sure that you are using a water based fluid and not oil based. Haze is mush more effective for special effects. Dry ice is very effective as well. I only use a fog machine (burst) when I need a quick puff of smoke. We just closed Once on This Island. Used haze the entire show. 

    Crit Fisher
    Lighting/Sound Designer
    New Albany High School