# NFPA 72 - rules regarding synchronization of strobes



## mshields (Sep 8, 2011)

We're doing work in an office building (happens to be a medical office building) and we're re-doing a single suite).  Our strobes in that suite will be synchronized but the strobes outside the suite are on an older system and will not be synchronized.   We're being told that we need to replace the strobes outside our work area.  i.e. in the corridor such that they synch with those in our space.  Of course, the corridor will need to be synched with all spaces it comes in contact with which is every single suite on the floor.  THis strikes me as nonsense.

But even if we have treat this like a new facility and provide to the letter of the NFPA 72, isn't there a provision in there to be between two sychronized zones but not more than that.  i.e. isn't it permissible to have an area where an occupant would be exposed to two but no more than two synchronized zones.

I thought there was verbage along these lines but can't find it, perhaps because it's not there.  Can anyone help?

Thanks,

Mike


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## cda (Sep 8, 2011)

not sure if this helps

  from 2010 edition

read the ballroom example:::

A.18.5.2.6

A.18.5.2.6 It is not the intent to establish viewing and synchronization requirements for viewing locations outdoors. As an example, there is no need for floor No. 1 to be synchronized with floor No. 2 if there is no visible coupling as in an atrium.

Studies have shown that the effect of strobes on photosensitive epilepsy lessens with distance and viewing angle.

As long as the composite flash rate is no greater than that produced by two listed strobes as allowed by 18.5.4.3.2, compliance is achieved.

Example: A ballroom has multiple synchronized strobes operating during an emergency, the doors exiting the ballroom are opened, and the strobes outside in the lobby and corridor are also operating. The strobes in the corridor and lobby are synchronized with each other, but the strobes outside the ballroom are not synchronized with the strobes inside the ballroom. This would be an acceptable application because the composite flash rate does not exceed that allowed by 18.5.4.3.2.

18.5.4.3.2

(3)*

Two groups of visible notification appliances, where visual appliances of each group are synchronized, in the same room or adjacent space within the field of view. This shall include synchronization of strobes operated by separate systems

A.18.5.4.3.2(3) The field of view is based on the focusing capability of the human eye specified as 120 degrees in the Illuminating Engineering Society (IES) Lighting Handbook Reference and Application. The apex of this angle is the viewer’s eye. In order to ensure compliance with the requirements of 18.5.4.3.2, this angle should be increased to approximately 135 degrees.

Testing has shown that high flash rates of high-intensity strobe lights can pose a potential risk of seizure to people with photosensitive epilepsy. To reduce this risk, more than two visible appliances are not permitted in any field of view unless their flashes are synchronized. This does not preclude synchronization of appliances that are not within the same field of view.

I think there is another section , may have to wait till Monday, unless someone comes up with something else

Not sure why they are making you do work outside your scope???       This is the ahj requireing it????????


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## cda (Sep 9, 2011)

You might ask moderator to move this to fire


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## AegisFPE (Sep 9, 2011)

Good call cda - done.


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## midwestFCO (Sep 9, 2011)

I typically treat it that as long as they are not in the same space (suite, tenant, etc) then I do not get concerned about it. The only time we (us and Building Department) has made them is if it is a suite within a multi-tenant building where they have glass walls between the corridor and the tenant space (usually atrium buildings).  In that case, they make them all be synchronized because it is not like the ballroom example where it only occurs when the door is open, the potential is there all the time.  Also, before someone says it, blinds did not satisfy the Building Official because they are not always closed.


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## FM William Burns (Sep 9, 2011)

Based on the spacing allowances in 72 for notification appliances in corridors one must also be careful at proximity locations at intersecting hallways in B uses.  If the eye/brain can pick up the flash at different distributions a sync module is required.


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## TJacobs (Sep 10, 2011)

I agree with midwestFCO


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## peach (Sep 21, 2011)

happens all the time, and we drop it on the building ownership; two or more (including the elevator lobbies, etc).  If replacing the synch module doesn't work, we refer to the FD.


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## Architect1281 (Sep 24, 2011)

I dont think strbes should be synchronized at all.

I think they should be sequential like traveling christmas tree lights.

Tthey should be high, they should be low, every occupant should have to carry an individual strobe that flashes slow if you get farther away from an exit and faster if you get close to an exit.

I think they should be like in the movie "Fifth Element" with Bruce Willis and Mila Jojovich.

Watch it when the casino goes into meltdown all the lights flash leading to the exits.

I think thats how it should be so thats what I make people do.

I know but they do it cause nobody wants to disagree with me.

Don't you agree FMB


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## FM William Burns (Sep 24, 2011)

???



			
				Architect1281 said:
			
		

> I think thats how it should be so thats what I make people do. I know but they do it cause nobody wants to disagree with me.
> 
> Don't you agree FMB


Nope!

Although, I like the idea of (the or a) traveling display of (assumed) floor proximity egress path marking leading occupants within an assembly, educational, high-rise, large industrial or health care to a exit though


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## mark handler (Sep 24, 2011)

Architect1281 said:
			
		

> I dont think strbes should be synchronized at all.


Photosensitive Epilepsy and Strobe Flash Rates

Those who are vulnerable to photosensitive epilepsy have voiced concern over the cumulative effect of seeing multiple flashing strobes in the field of view.

An example of this would be an individual standing at the cross-point of an “L” shaped corridor that contains multiple strobes. During an alarm or test of a system, the person could be exposed to a cumulative flash rate that might increase the probability of seizure and photosensitive response.

Although aggregate strobe flash rates in a fire system and their relationship to those persons with photosensitive epilepsy are not in any current law or standard, it is an issue that should be addressed with diligence when installing and/or upgrading fire systems.

Although one solution involves synchronized (simultaneous flashing) strobes, other options have been outlined by NFPA and the proposed ADAAG. The NFPA makes it clear in Chapter 6, Section 6-4.4.1.1 that synchronization is only one of several installation configurations that the systems designer can use to minimize multiple strobes flashing in an individual’s field of view. These four options are outlined on page 8. Also, in 1996 the NFPA changed its maximum acceptable strobe flash rate

According to the Epilepsy Foundation, three percent of epileptics that are exposed to flashing lights (at certain intensities or to certain visual patterns) can trigger seizures.

Three percent may not sound like a lot, but there over 3 million people who suffer from epilepsy in America alone. This equates to around 90,000 people who are affected.


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## Architect1281 (Sep 25, 2011)

FMB I hope you realize my tounge was so far in my cheek I looked like a squirrel.

with that in mind

Mark H thats what areas of refuge are for, and the could have a special No strobe zone adjacent to the peanut free zone.


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## mark handler (Sep 25, 2011)

Architect1281 said:
			
		

> Mark H thats what areas of refuge are for, and the could have a special No strobe zone adjacent to the peanut free zone.


Nice, and what you you have to say about other minorities.


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## Architect1281 (Sep 25, 2011)

More Cowbell > we can only make the Areas of refuge so big?

keep in mind MH we both have cartoon characters as Avatars??

sense of Yuma please it's more than a city in Arizona


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## mark handler (Sep 25, 2011)

The synchronization of strobes has nothing to do with the Areas of refuge.

Just like a footing size has nothing to do with exit width, your comment makes no "sense".

The thread is about synchronization of strobes.


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