Why does the Yahoo! front page logo today has a running fire hydrant? Isn't it illegal to open a hydrant?
I completely agree that if this is truly for a safety concern, please just buy one, but if you are creating one for a school project, a infrared LED and detector can be used. This would allow smoke to come between the LED and detector breaking the circuit. When the circuit is broken, the circuity should sound an alarm or noise maker of some sort. They sell little LED/detector devices in one unit that are used for spoked wheel movement detection, such as what are used in the wheel based mice.
Wear what is comfortable. If you are renting then the rental comes with a goggle system to protect your eyes. If you are worried about geting hurt then double up on the shirts, or wear a sweat shirt but its gonna get hot around this time of year.
As you probably know the red wire is used to turn on all alarms in the house if any one of them goes off. The electrician should know that if he is licensed. He is obligated to wire a building to the latest code of your district. He is responsible to fix it at his own cost. If he doesn't you can sue him and make a formal complaint with the state licensing bureau. If wallboard needs to be cut away and repaired to fix it, he is responsible for those costs as well. You can tell the inspector and he will back you up for the repairs and in court if needed. Don't use the bare wire as a current carrying ground. That can be fatal. The difference being that you can cut the bare wire and hold both ends with your hands when power is on without effect. If you do that with a current carrying ground (white) you will be shocked. They are not the same. You could run a single strand of red MTW or THHN along the path of the other wire and make the connections with it. It has to be protected the same as the Romex where exposed.
