Fire Alarm T Taps

[moresi]

What is the best method out thewre for t tapping fire alarm SLC conductors? I am looking for the easiest and safest suggestions.

[peter d]

Make sure the manufacturer of the FACP allows it, and make sure you local codes allow it.

T-tapping is strictly forbidden by local codes in my area.

[Security101]

Originally Posted by peter d

T-tapping is strictly forbidden by local codes in my area.

Peter, If I may ask - what do they allow - only home runs?

Do they allow properly marked/labeled T Tapping in junction boxes?

I've never run into a problem - as long as the FACP was designed for it...

Jim

[peter d]

Originally Posted by Security101

Peter, If I may ask - what do they allow - only home runs?

Do they allow properly marked/labeled T Tapping in junction boxes?

I've never run into a problem - as long as the FACP was designed for it...

Only a Class A loop is allowed. No T-tapping of any kind is allowed under any circumstances. If you need to add a device you have to interrupt the look somewhere to insert a device.

Class B loops are also allowed for local (not monitored or municipally connected) but they must be wired like a Class A system with the EOL resistors terminating back in the FACP on a terminal block as opposed to the last device.

[quogueelectric]

Originally Posted by Security101

Peter, If I may ask - what do they allow - only home runs?

Do they allow properly marked/labeled T Tapping in junction boxes?

I've never run into a problem - as long as the FACP was designed for it...

Jim

T taps are ALLWAYS a bad idea. When a fa system is wired according to the blueprint in a class A fashion it is much easier to troubleshoot and maintain when you know exactly how it was wired. When you work for a large company you cannot wire everything yourself and when someone screws up it is a breeze to fix but when you have t taps all over the place it is just a lesser quality job.

[TOOL_5150]

I have never done Fire alarm stuff... What is a T Tap?

~Matt

[quogueelectric]

Originally Posted by TOOL_5150

I have never done Fire alarm stuff... What is a T Tap?

~Matt

A class A fa system has say up to 99 devices on a loop smokes for example. It used to matter in and out of the bases more years ago. Start at device 1 go to 2 go to 3 ect......ect.......... to 99 then back to the facp panel with an eol resistor located in the panel. One big numerically sequenced loop. Modern day electronics hae addressable devices which are not just a mechanical switch yet an interactive addressable network of heads who report through a network address instyead of a switch. The computer checks addresable heads one at a time from the main computer. Hello device 1 are you there... device 1 says yes I am here.....Ok device 1 are you in alarm? No I am not in alarm..... OK device 2 are you there? Yes I am there ..Ok device 2 are you in alarm?? ect ect through 99 . Now these devices do not have to be wired in a big series loop because they are on a parallel network . A t tap is just a wiring point in parallel instead of series. Like if you wired device 76 in between device 4 and 5 . It will work but is much more difficult to troubleshoot with t taps all over the place.

[Security101]

Most definitely a class A circuit is a better option and provides more redundancy, but class B's are the norm around here, depending on occupancy of course. (mostly an industrial area)

We always print our runs, taps, devices, etc completely and accurately so service is not an issue. And we only do this (class b's) with addressable systems - so if there's a failure - we don't have to hunt it down - we know where it is...

Some of our class B runs will terminate in the can and may be connected in a partial class A fashion anyway...

Jim

[quogueelectric]

Originally Posted by Security101

Most definitely a class A circuit is a better option and provides more redundancy, but class B's are the norm around here, depending on occupancy of course. (mostly an industrial area)

We always print our runs, taps, devices, etc completely and accurately so service is not an issue. And we only do this (class b's) with addressable systems - so if there's a failure - we don't have to hunt it down - we know where it is...

Some of our class B runs will terminate in the can and may be connected in a partial class A fashion anyway...

Jim

Whether class a or b I find following the print is the key to a quality install. Knowing where the cabling routes are is crucial to expansion /troubleshooting/maintenance. I have seen many fa jobs belly up because of a simple skinned wire and untrained fa people panicking on the troubleshoot. Just take a deep breath and say this is usually something very simple. Use your troubleshooting skills and find it in a quick orderly fashion. A clearly drawn asbuilt is awesome to troubleshoot and seldomly available. All information is a plus.

[nhfire77]

T - Taps are fine if, you use a Loop Isolation Module.


IMHO