First time buyers of security systems often ask questions about what they should buy. They ask friends who have systems and salespeople who sell them.
Very often, friends don't know whether they have a genuine system or just a collection of parts. But they do know whether the installation was neat. They also know whether their alarm company offers timely, efficient service. Yes, it's OK to disregard comments like "they wouldn't do exactly what I wanted" since these may refer to things that were impractical, illegal or contrary to a life safety code. But do pay attention to comments like "they finished on time and cleaned up as they worked."
The following questions and answers will help explain some of the many qualities you should look for in a security system and separate them from the bias of sales people.
Every accessible door and operable window should be protected. All glass windows should be protected with some sort of shock/audio detector. Windows can also be protected using alarm screens instead of contacts and shock/audio detectors. Obviously in a three story residence, the windows on the third floor cannot be opened by normal means; screens, vibration sensors or audio detectors should be sufficient if the windows are kept locked. Rather than contacting these third floor windows, the money could be spent on additional interior protection or other security features like fire detection. However, if you would feel unsafe with these windows uncontacted, contact them. It's your security and your peace of mind.
Garage overhead doors are a special case. A lot of people get these doors contacted and then pay extra to have the door bypassed automatically when the garage door opener is used. Since the only way to open these doors is by using the garage door opener, they are paying for the door to be protected and then paying more for it to be unprotected. Don't spend money to protect a door and then spend more to bypass the protection every time the door is used. Spend your money on additional protection or added features.
If there is no automatic opener, a contact can be useful protection on a garage door. If there is an automatic opener and you wish to protect a boat or trailer stored in the garage, there are devices designed to attach to the boat or trailer.
This depends on you and your installing company. Does the burglar seeing the switch go elsewhere because he now knows you have more than just a sign and some decals? Can the burglar defeat the contact just because he can see it? Some people cannot tolerate the sight of normal surface mounted contacts or feel unsecure because "the burglar knows what's there." Other people feel secure seeing the switches because "the burglar knows I really do have a system installed by a professional." Surface mounted switches often are easier to install. Although the price for installing recessed switches may be higher with some companies, generally prices run the same for either switch.
One hype concerning recessed switches is the size of the switch in a wooden door or wooden door frame. If the switch is recessed in the frame, you cannot see it when the door or window is closed. As long as it fits the frame properly without overlap, it does not matter what the diameter of the switch is.
In steel doors and steel door frames, the switches and magnets need to be isolated from the metal so they can work properly. These switches and magnets are usually inserted into a 3/4 inch or larger hole. The larger switches are usually used. However, plastic adapters can be used to hold a smaller switch in the hole.
An End-Of-Line resistor supervises the wiring between the alarm panel and the switch. Some panels have a limited number of detection zones and do not require EOL resistors. But if the panel can use EOL resistors to supervise the wiring, the resistors should be used. If more than one detection device is on a single detection circuit, the EOL should be at the last device. When feasible, every alarm detection device should have an EOL resistor at the device. If the EOL resistor is at the burglary contact on a door, the panel sees the wire open when the door is opened and sees the resistor when the door is closed. The thief who shorts wires together hides the EOL resistor from the panel, letting the panel know that something is going on. The thief who cuts the wire causes an open circuit, the same as if he had opened the door.
Hold-up alarms and Fire alarms use an "open circuit" detection scheme. The panel normally sees the EOL resistor at the end of the detection circuit. A short on the wire causes an alarm and a break in the wire causes a trouble report.
Since normally closed switches can weld due to high voltage like lightning, the normally closed switches used for burglary detection must be checked after severe weather to see that they still work properly. Since devices on a "open circuit" normally cannot weld open, lightning and power surges should not "weld" these switches into an inoperable state. Some security systems even use this high security mode for their burglary devices.