Presently available are tools that make it much easier to install security/fire-alarm systems in existing buildings. You may now attach a drill bit to a long, flexible spring steel shaft. This makes it possible to easily manipulate a drill bit in walls to accomplish complex installation maneuvers in existing buildings. There are some other tools that are helpful with cable installation. An alignment tool may be used to hold the bit and shaft steady while drilling. Line recovery devices grip the holes located in the shaft end of the drill, thus, allowing one person to quickly fish wires or cables through partitions and shaft extensions.
Where it becomes necessary. to remove floorboards during a security/fire-alarm installation. it should be done with the greatest of care so that the edges are not split. On the finished job, when the boards are replaced, split edges make a poor appearance Special saws may be purchased for cutting into floors or other surfaces without having to drill holes to start the saw. Then if the tongue (on tongue- and-groove boards) is split off with a thin, sharp chisel driven down in the crack between the boards, the board from which the tongue was removed can be pried up carefully without damaging the rest of the floor.
If at all possible. a reversible drill motor should be used to withdraw the bit from the wall. The motor should be running only when the bit is actually passing through a wood member. When you are drilling, force is exerted in one direction. When the bit is being removed. it is removed at a different angle and force is exerted from a different direction. This is why the reverse is used. If the flexible shaft is being used with drill motors with no reverse, it would be better to exert force to pull the bit from the hole with the motor running because chances of an easy recovery without damage are much better with the motor running.
When you are drilling from an attic or crawl space, be certain not to select an area directly above or below a door since this will result in property damage. It is also good to keep a slight tension on the wire when it is being pulled from overhead so that it will not get tangled with the bit and become damaged.
The shaft should not be bowed any more than absolutely necessary to accomplish the job. Excessive bowing will decrease the life of the flexible shaft. Drill motors, of course. should be adequately grounded or else have insulated handles.
Assume that an outlet box for an infrared photoelectric detector is to be installed above a countertop in a residential kitchen to sense entry of unauthorized persons through the kitchen door. If. upon investigation of the space inside of the partitions, it is found that a 2- by 4-inch (5- by 10-cm) wood member (fire stop) blocks the route from the outlet hole to the basement area where the alarm control station is located, an alignment tool must be used.
The flexible shaft, containing a drill bit. is placed through a cut outlet-box opening and then the special alignment tool is attached to the shaft, as shown in figure 8-6. The shaft will bow back toward the operator by keeping the alignment tool in the same position to the shaft and by lifting the handle. As the bit is lowered into the wall cavity, the operator can feel the bit strike the inside wall. When the bit is aligned correctly on the wooden member, the alignment tool is removed while keeping downward pressure on the bit so that it will not slip out of place, and the hole is drilled through a fire stop. This hole will then act as a guide for drilling through the floor plate, as shown in figure 8-7.
Figure 8-6.The alignment tool is attached to the shaft, ready for operation.Continue Reading