Fire Alams

[Fearno42]

Was curious as to why most of the older electricians I meet,Label the ins and outs when pulling fire alarm cable.I understand it could help with trouble shooting,but did it matter in some of the older systems.Always willing to learn,but no one could give me justifacation as to why?

 

[roger]

It's simple, most older analogue F/A systems were series circuits and labeling "in and out" just kept things straight as to which set of conductors was coming and going.

Roger

 

[rdbutler]

The best reason that I can think of is for troubleshooting. If you have a groundfault on the wire labelled 'IN' then you know the problem is toward the panel.

On today's addressable systems that are able to be T-Tapped and Star-Tapped, that labelling scheme doesn't always make sense. It would be nice to put the address of the previous device on the wire at a splice point, but that's not always practicable either.

Even on modern FA systems, the NAC circuits are series devices and do have in's and out's and end-of-line supervision so they could still be labelled that way.

All that said, our techs don't label the in's and out's at every strobe. There are ways to tell which direction a trouble is, such as putting a tone on the circuit or shorting one end, etc.

I hope that helps in your understanding, but for now, do what the older techs tell you to do and you'll go far in your company