Smoke detector placement is important when designing a fire life safety system for obvious reasons. In this article, we are going to focus on the smoke detector placement requirements per NFPA 72 2010 edition for smoke doors with
magnetic door holders. If you are using smoke detectors for the purpose of door releasing service than the following code shall apply:
NFPA 72 2010 edition:
17.7.5.6.5.1 (A)
If the depth of the wall section above the door is 24 inches (610 mm) or less, one ceiling mounted smoke detector shall be required on one side of the doorway only, or two wall mounted smoke detectors shall be required, one on each side of the doorway.
17.7.5.6.5.1 (B)
If the depth of the wall section above the door is greater than 24 inches (610 mm) on one side only, one ceiling mounted smoke detector shall be required on the higher side of the doorway only, or two wall mounted smoke detectors shall be required, one on each side of the doorway.
17.7.5.6.5.1 (C)
If the depth of the wall section above the door is greater than 24 inches (610 mm) on both sides, two ceiling mounted smoke detectors or two wall mounted smoke detectors shall be required. One on each side of the doorway.
In the above picture, you can clearly see that the header or space above the doorway with magnetic door holders is less than 24 inches (610 mm). However, the installing fire life safety company installed a smoke detector on the ceiling on both sides of the doorway. This smoke detector placement is not required but it never hurts to have extra coverage. Just thought I would point it out.
A cable toner can prove to be a very useful tool in the fire alarm system installation and service business. If you do not know, a cable toner is a battery operated device that places a tone across cables assisting in location and verification. You can simply connect the toner to a pair of wires and then move between junction points with the provided wand looking for the tone.
Later, I may write a post on basic operation of a toner but for now, I am going to show you a little trick to help verify your fire alarm voice evacuation speakers are connected correctly. 
Of course it is highly recommended to test out your fire alarm speaker circuit with a multi-meter before coonecting to your amplifiers. With a multi-meter, you can test for reverse polarity (with the diode check), ground faults, shorts and continuity with the resistance setting and fianally check for AC inductance with the AC voltage setting.
Once you have verified all is good on your fire alarm speaker circuit we can move on to the cable toner test. I have included a simple video to show the connections and the tone you should receive at all of the speakers connected to the fire alarm circuit.
Make sure to turn on the cable toner to the "TONE" setting and connect it to the circuit. Red to red and black to black. This will allow the cable toner to produce a tone across the fire alarm speaker circuit and pronounce it through the actual speakers. Once this step is completed, walk around the site and verify that you have a fire alarm sound or tone through all of the speakers on the circuit.
