smoke-detectors
I just got done wiring boxes for my hardwired smoke detector system and am about to start installing detectors. When testing in the end, I heard they sell some test aerosol spray which is the officially (I guess) endorsed way of doing it.
Just out of curiosity, I was wondering if there are alternative safe (as to not burn something or the whole house down) and efficient ways of doing it. I had done it before by burning a piece of paper near one but I'm thinking there are better ways.
According to the guide handed out by my local permitting office, which doesn't cite electrical or fire codes but does detail what they look for:
A smoke detector should be placed inside the door of each bedroom 24 inches from the nearest walls or centered on the doorway 24 inches from the wall holding the door.
A combination smoke alarm / carbon monoxide detector should be placed in any hallway that leads to bedrooms, where it enters the main part of the house, again, centered in the hallway on the ceiling and 24 inches from where the hallway connects to the rest of the house.
All of the smoke detectors should be hardwired to a circuit on the house's mains and should talk to one another via a third wire.
Ionization smoke detectors use a radioisotope to generate a very small electrical current, which when interrupted causes an alarm to sound. These types of alarms use a metal–oxide–semiconductor field-effect transistor (MOSFET) to prevent the alarm from sounding, as long as the tiny current is flowing from the detector.
A simple dumbed down version of the circuit, might look something like this.
Notice the 9V battery is connected to the Source contact of the MOSFET, the detector is connected to the Gate, and the Alarm is connected to the Drain. This means that as long as there is a current on the gate, current will not flow from the source to the drain. If something (smoke) interrupts the current flow to the gate, current will flow from the source to the drain and the alarm will sound.
If you add a normally closed switch to the circuit, like so.
Opening the switch will prevent current from flowing to the gate, simulating a loss of current flow from the detector. Which in turn, will cause the alarm to trigger.
So when you press the test button on an ionization type smoke detector, you're not actually testing the circuits ability to detect smoke. Rather, you're testing the circuits ability to react to a loss of current flow to the gate contact of the MOSFET. You're also making sure the battery is not dead, and has enough juice left to sound the alarm if need be.
Best Answer
The sprays are the official way to do it. I don't really like the chemicals in them, but I do use them.
I've also used a candle, which I snuff out below the detector. This is safer than the paper and produces more reliable smoke.