Clarification on two distinct groups of synchronized strobes

[cda]

Maybe it is whatever makes you feel good???

 

[BigAbacus]

NFPA 72, 2013
18.5.5.4.2
Handbook indicates the purpose of the synchronized requirements are guided by the human eye and its ability to view a flash of light at a 120/135 degree field of vision. The code’s revision in 07 clarified the intent of the multiple detectors two/ groups.

Handbook (18.5.5.4.2) “The flash rate was adjusted so that two appliances (or groups of synchronized appliances) not flashing in unison cannot produce a flash rate that is considered dangerous. If more than two appliances or groups of synchronized appliances can be viewed at the same time, they must be synchronized”.

It has always been my understanding the the code meant that if there are two visible and not synchronized its not compliant OR if there are two groups within the same field of view and both groups of appliances are not synchronized, they are not compliant.

Example - would be your common corridors shared by two separate groups of strobes. One end or half the length by lets say the existing system and the other half length by the new system. Those groups therefore need synchronization.

So my opinion would be the common corridors are non-compliant. I’ve seen this many times in large industrial, storage and healthcare expansions connecting corridors to buildings etc.

I would recommend having your electrical engineer and or fire alarm service provider check availability of ones system expansion of the notification alarm circuit(s) to cover the corridors and possibly separate the common corridor with detection alarm activated self closing doors keeping the corridors synchronized by the applicable system expanded circuits.

“The flash rate was adjusted so that two appliances (or groups of synchronized appliances) not flashing in unison cannot produce a flash rate that is considered dangerous. If more than two appliances or groups of synchronized appliances can be viewed at the same time, they must be synchronized”.

This is the situation that is in question. “MORE THAN” is the key. Two strobes do not need to sync, just as two distinct groups do not need to sync. The handbook mentions the scenario of a ballroom and a area outside of the ballroom. The ballroom devices must sync and the area outside of the ballroom must sync but they do not necessarily need to sync between the two groups. This is due to the maximum flash rate of each group not being cumulative together to cause an issue of exceeding the 5 flashes per second that could potentially cause seizure.

Erratic strobes is the situation that we have all encountered when a system is improperly installed or lacking is design principles that accommodate are larger multi panel system. This is truly an issue with random flashes in a common space. We have even seen circuits that were stretched beyond their limits and have an almost runway effect. These are both considered non-compliant and not acceptable.

Modifying the systems in question are not really a possibility due to the quantity of devices and sync protocols differing between the two systems. The NFPA 72 code is considered a minimum for compliance meeting all of ADAs requirements that are incorporated. 18.5.5.4.2 states that I have meet the requirements of the code. I have had the issue with only two strobes being out of sync but not two groups. The same code applies.

I was looking for addition case studies or peoples past experiences with the same scenario in other large facilities that were deemed acceptable. I understand that each jurisdiction is slightly different but all follow the NFPA 72 with slight deviations per suppliementals to muddy the waters.

I appreciate everyone’s time to respond and provide input

 

[cda]

Will if you have two groups

You will have more than two strobes out of snych

In the end the local ahj is one you have to make happy

 

[FM William Burns]

Totally understand the ballroom and lobby outside the ballroom on different flash sequences. That’s the intent of compliance point. Your post suggests your issue is in a “common corridors(s)”. If the corridors are covered by 2 strobes that don’t share the same flash rate or are not synchronized then the visible notification appliances in said corridors are non-compliant. I don’t believe the hang up is the “two” or interpretation of two. If it’s only two in the area or groups and visible by the eye they need to be synchronized.

 

[cda]

Regulations, Codes & Standards Q&A: Strobe synchronization - Regulations, Codes & Standards

www.healthcarefacilitiestoday.com

 

[cda]

“The flash rate was adjusted so that two appliances (or groups of synchronized appliances) not flashing in unison cannot produce a flash rate that is considered dangerous. If more than two appliances or groups of synchronized appliances can be viewed at the same time, they must be synchronized”.

This is the situation that is in question. “MORE THAN” is the key. Two strobes do not need to sync, just as two distinct groups do not need to sync. The handbook mentions the scenario of a ballroom and a area outside of the ballroom. The ballroom devices must sync and the area outside of the ballroom must sync but they do not necessarily need to sync between the two groups. This is due to the maximum flash rate of each group not being cumulative together to cause an issue of exceeding the 5 flashes per second that could potentially cause seizure.

Erratic strobes is the situation that we have all encountered when a system is improperly installed or lacking is design principles that accommodate are larger multi panel system. This is truly an issue with random flashes in a common space. We have even seen circuits that were stretched beyond their limits and have an almost runway effect. These are both considered non-compliant and not acceptable.

Modifying the systems in question are not really a possibility due to the quantity of devices and sync protocols differing between the two systems. The NFPA 72 code is considered a minimum for compliance meeting all of ADAs requirements that are incorporated. 18.5.5.4.2 states that I have meet the requirements of the code. I have had the issue with only two strobes being out of sync but not two groups. The same code applies.

I was looking for addition case studies or peoples past experiences with the same scenario in other large facilities that were deemed acceptable. I understand that each jurisdiction is slightly different but all follow the NFPA 72 with slight deviations per suppliementals to muddy the waters.

I appreciate everyone’s time to respond and provide input

Hummmm

After reading a little I see what you are trying to say



Normally, the fire alarm strobes rate is 1 HZ (Hertz) which translates to one flash per second, but if a room or hallway has, let’s say, two or three strobe lights within line of sight, they now have the potential of appearing to flash two to three times per second.

Fire Alarm Strobe Synchronization: Why Is This NFPA Requirement So Important? - PlatinumFire.us

If you have ever witnessed a commercial fire alarm inspection and wondered why fire alarm strobe synchronization is so important, then you should take a minute to read this article […]

platinumfire.us

Not into HZ or flash rates

But maybe if you are not exceeding what 72 allows, might work???

Once again convincing the ahj

Maybe a fire protection engineer or a guru from the brand supplier of your equipment might be able to convince the ahj

Have you emailed or called Al?? To see what he says??

 

[cda]

“The flash rate was adjusted so that two appliances (or groups of synchronized appliances) not flashing in unison cannot produce a flash rate that is considered dangerous. If more than two appliances or groups of synchronized appliances can be viewed at the same time, they must be synchronized”.

This is the situation that is in question. “MORE THAN” is the key. Two strobes do not need to sync, just as two distinct groups do not need to sync. The handbook mentions the scenario of a ballroom and a area outside of the ballroom. The ballroom devices must sync and the area outside of the ballroom must sync but they do not necessarily need to sync between the two groups. This is due to the maximum flash rate of each group not being cumulative together to cause an issue of exceeding the 5 flashes per second that could potentially cause seizure.

Erratic strobes is the situation that we have all encountered when a system is improperly installed or lacking is design principles that accommodate are larger multi panel system. This is truly an issue with random flashes in a common space. We have even seen circuits that were stretched beyond their limits and have an almost runway effect. These are both considered non-compliant and not acceptable.

Modifying the systems in question are not really a possibility due to the quantity of devices and sync protocols differing between the two systems. The NFPA 72 code is considered a minimum for compliance meeting all of ADAs requirements that are incorporated. 18.5.5.4.2 states that I have meet the requirements of the code. I have had the issue with only two strobes being out of sync but not two groups. The same code applies.

I was looking for addition case studies or peoples past experiences with the same scenario in other large facilities that were deemed acceptable. I understand that each jurisdiction is slightly different but all follow the NFPA 72 with slight deviations per suppliementals to muddy the waters.

I appreciate everyone’s time to respond and provide input

any resolution ???