Class X Fire Alarm System - Isolators per device?

[rstalvey]

My specs say "The Addressable Interior Fire Alarm System shall be a complete Class X (NFPA 72, 2010 MOST CURRENT EDITION) level 1 supervised, non-coded, addressable fire alarm system conforming to NFPA 72, UL 864 UOJZ Ninth edition and UL2017."

A few pages later in the spec, in the "Isolator Module" section, it says "At least one isolator module shall be provided for each 1 device in all facilities with sleeping areas."

My question...are these two sections contradicting one another? The owner/GC claim that simply requiring a Class X system requires two isolators per device. If this is indeed the case, they probably have me with the "most stringent requirement shall govern" catch-all clause. If not, this could be a case of owner preference rather than a code requirement.

Please help!!

 

[gadfly56]

My specs say "The Addressable Interior Fire Alarm System shall be a complete Class X (NFPA 72, 2010 MOST CURRENT EDITION) level 1 supervised, non-coded, addressable fire alarm system conforming to NFPA 72, UL 864 UOJZ Ninth edition and UL2017."

A few pages later in the spec, in the "Isolator Module" section, it says "At least one isolator module shall be provided for each 1 device in all facilities with sleeping areas."

My question...are these two sections contradicting one another? The owner/GC claim that simply requiring a Class X system requires two isolators per device. If this is indeed the case, they probably have me with the "most stringent requirement shall govern" catch-all clause. If not, this could be a case of owner preference rather than a code requirement.

Please help!!

The owner/GC is correct. Class W requires that a signal be capable of being transmitted in the case of a single open or a single short on the signal line circuit (SLC). This refers only to SLC's, since you can't have a Class X indicating device circuit (IDC, for conventional devices) or a notification appliance circuit (NAC). Under the 2007 edition this was also designated "Style 7". In order to achieve the requirement for operating through a single short, each device will require two (2) isolation modules, so it looks like: -----I--D--I-----I--D--I----- where "I" is the isolation module and "D" is some addressable device. The additional requirement of "level 1" means that all wiring has to be in metallic raceway.

 

[rstalvey]

Thanks

Thanks

Not necessarily the answer I wanted, but an answer all the same. I've been trying to research this for a while on my own with no luck Thanks for the insight.

 

[ron]

The owner/GC is correct. Class W requires that a signal be capable of being transmitted in the case of a single open or a single short on the signal line circuit (SLC). This refers only to SLC's, since you can't have a Class X indicating device circuit (IDC, for conventional devices) or a notification appliance circuit (NAC). Under the 2007 edition this was also designated "Style 7". In order to achieve the requirement for operating through a single short, each device will require two (2) isolation modules, so it looks like: -----I--D--I-----I--D--I----- where "I" is the isolation module and "D" is some addressable device. The additional requirement of "level 1" means that all wiring has to be in metallic raceway.

You could also look at it from the fact that they dictate Class X for SLC (signaling line circuits) but have NO requirement for IDCs and NACs. Maybe those could be Class B

 

[gadfly56]

You could also look at it from the fact that they dictate Class X for SLC (signaling line circuits) but have NO requirement for IDCs and NACs. Maybe those could be Class B

Maybe, but I wouldn't assume one way or the other. Usually folks spec'ing Class X are looking for the top line as far as signal integrity is concerned. If this is a high rise, the OP is lucky they didn't ask for "Level 2", which would have meant CI or CIC cable for any risers.

 

[Abdel Rahman Mohamed]

It's depend on the client requirements and manufacturer recommendations for single or double isolator, in our project we are going to use single isolator per each.