Fire alarm stobe lights dont flash in sync in Plant.

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VinceS

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During a inspection I was informed that all of the strobes for the hearing impaired shall be required to flash in sync. I has something to do with
epilepsy, or persons with a potential seizure condition. No reference was provided, is this here-say, or a local Florida reference. This is kinda off topic
for an electrical forum but most of us electrical personnel frequently install or replace these alarms.

Thanks in advance
 
Field of View

Field of View

In NFPA-72 (2007) see 7.5.4.3.2 (4) and 7.5.4.4.7 for synchronization requirements. Basically, if there are MORE than two (2) devices in the field of view, they have to be sync'd.
 
Thanks all...

Thanks all...

I've started to read NFPA 72 after finding mention of it in previous posts. Is there any quick fix, or is a major upgrade required? What have others
done to repair this issue?
 
VinceS said:
I've started to read NFPA 72 after finding mention of it in previous posts. Is there any quick fix, or is a major upgrade required? What have others
done to repair this issue?
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You need sync modules, talk to your fire alrm vendor.
 
Since there may be more than one way to accomplish this depending on what brand(s) and model(s) of fire alarm panels, strobe booster power supplies, and strobes you have and their layouts, you may want to get more than one quote. Save any working strobes that need to be replaced, as they can be used to repair faulty devices (in areas like a restroom where synchronization is not required*) that turn up during future inspections.




*Unless it's a large restroom needing 2 or more strobes for coverage, in which case they do have to synchronize.
 
MichaelGP3 said:
Since there may be more than one way to accomplish this depending on what brand(s) and model(s) of fire alarm panels, strobe booster power supplies, and strobes you have and their layouts, you may want to get more than one quote. Save any working strobes that need to be replaced, as they can be used to repair faulty devices (in areas like a restroom where synchronization is not required*) that turn up during future inspections.




*Unless it's a large restroom needing [2 or] more than 2 strobes for coverage, in which case they do have to synchronize.
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Fixed it for ya!:D
 
gadfly56 said:
Please see my reply at #3.
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OK I was not paying attention to what it said.

Any idea why more than two in field of view requires syncronization? Seems to me more than 1 should require it.

A single strobe drives me nuts to have multiple ones not in sync may just cause my head to explode:)
 
kwired said:
OK I was not paying attention to what it said.

Any idea why more than two in field of view requires syncronization? Seems to me more than 1 should require it.

A single strobe drives me nuts to have multiple ones not in sync may just cause my head to explode:)
Click to expand...

My understanding is that the critical threshold for triggering an epileptic siezure in those susceptible to photonic triggers is in the area of 16-25 Hz but has been reported as low as 3 Hz. The usual flash rate for FA strobes is 1 Hz. With 2 unsynced strobes, the minimum effective strobe rate is 2 HZ if they were 180 degrees out of phase. There is also pulse duration to consider when figuring this out. At some point, the two strobes will look like a single longer period flash. So anyway, since they aren't synced, they'll probably drift back and forth. With 3 strobes, you now might wind up with a 3 Hz effective flash rate at some point, at the lower threshold of triggering a siezure.
 
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