ECN Forum Forums General Topics of the Trade General Discussion Area alarm system wiring

jkraft,

As you look at the prints for this job, check to see who is responsable for firestopping. It might sound like a small thing, but if you are working in a school, most of the holes made through walls might have to be firestopped to prevent spread of fire. The tubes of "approved" firestopping caulk can be quite expensive. ( Or so I have heard) Also watch your approved drawings to make sure that the strobes and horns are in the correct spot. If in doubt, check with the construction dept., they should be willing to help you.

If you can, walk the job with a set of prints in hand, and check locations for sanity..
Check with the building occupants to see if there are any conflicts, especially if the space has any special uses.

We had the alarm guys come thru at Stanford, and wire our radio station.. However, there were some obvious spots where the designer didn't take certain things into account, such as:

The end of a hallway:
the strobe was located on the hinge side of a door, that in the open position would completely cover the strobe, and probably smash it in the process.. (the strobe was raised to clear the door)

next to front door:
the door is in a corner, with a wall parallel to the path, where the manual pull station was to be located, (surface mounted, sticking out 6" into the path, subject to physical damage). This was the main door into the radio station, and equipment was regularly moved thru that door. The light switches were located on the other side of the door, on a wall perpendicular to the path. (the pull station was relocated to above the light switches)

Upstairs in one of the theatres:

strobes located immediately adjacent to the proscenium, on walls that were regularly masked with scenery. (strobes were relocated further offstage.)

There seemed to be a recurring theme of mounting strobes next to doors, on the hinge side, and 4-6" below the top of the door, instead of on the latch side, or 4-6" above the top of the door.

Couple of comments techie.

Yeah the hinge side of a door is a bad choice, raising the horn strobe to clear the door is a usually violation of the height.

The visual devices need to be around 82" AFF I can not remember the exact measurement.

The pull stations need to be within 5' of the door, many times that ends up with some pretty ugly installations on door mullions.

I can only speak for this area but once I have stamped approved prints from the FD I can not move devices. They go where shown...insane or not.

I try to place my pull stations where I can have one hand on the door knob and the other hand on the pull station. As far as strobes I mount them 80" to the bottom NO higher. I will move them to the strike side of the door, I believe mounting them behind doors is a violation.

In this case, the door was at the intersection of two hallways, and they wanted the strobe to be visible from both directions, so they could not move it to the other side of the door. Reversing the swing of the door was not an option, nor was changing the door to open into the room, instead of out, both because of clearance issues.

It probably ended up slightly higher than it should have been, but the option was for it to be smashed the first time the door was opened to the stop, and even if it had survived, it would have been obscured about 80% of the time that the station was occupied. (this was a basement hallway, with conduits, piping, and ductwork overhead. no finished ceiling in the hallway.)

The pull station ended up immediately adjacent to the door, on the latch side, within 8" of the door, in a much better position.

We felt very strongly that it would have been a hazard where it was originally installed, because with all the band equipment that was carried in thru that door, somebody was going to rip their arm or their shoulder open.

Another thing that I almost forgot.. The designers need to take the activities in the building into account when specifying audible devices.

I remember an alarm test at another school, where the audible device was not instantly recognisable as a fire alarm.

I was up in the prop loft, about 10 feet from the device when it went off, and It sounded exactly like the table saw in the shop immediately downstairs. (Wahhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh)

It wasn't until I climbed out of the loft, and saw the strobes that I realized that it was the fire alarm. If it had been pulsed, it would have been much more obvious.

NFPA 72 (National Fire Alarm Code) spells out locations for FA devices fairly well, if you can find them (and I usually can't). Per 7.5.4* “Appliance Location: Wall-mounted appliances shall be mounted such as that the entire lens is not less than 2.0 m (80 in.) and not greater than 2.4 m (96 in.) above the finished floor.” *Of course there are provisions for a ceiling lower than 80in. If mounted below 80" because of the ceiling height then the device, for lack of better words, must be derated (and not more than 6” below the ceiling). See Annex A 7.5.4. In a corridor, if mounted on a side wall (as opposed to wall mount over a door, or ceiling mount), the strobe must no more than 15' from the end of the corridor (yes I mean feet, not inches per 7.5.4.2.5)! If you can get a copy of the code, do it, as I have had the fire marshall tell me the strobe had to be 15' minimum, not max, from the end of the corridor and lost the battle because I didn't have my book with me.

Pull stations must be mounted between 3 ½' and 4 ½' per 5.12.4, and within 5' of the exit door on each floor per 5.12.6.