Cat 5 is quite a large wire. It would probably be better to use plain old 4
conductor solid phone wire for the doors and windows. This is because
sensors in homes are usually concealed. If you have a window which slides
up/down for example, the wire would come up from the bottom into the area
where the window slides down. Then be soldered to a thin contact and the
wire and contact lie flat at the bottom of the window. A magnet is glued to
the bottom of the sliding portion of the window. A large fat wire may not
allow the window to close.

Some visible door contacts (like those used on business doors) have small
screw terminals. It would be easier to wrap a small solid wire around these
screws than a stranded cat 5 wire. (Look at business alarm sensors)

Also note that alarm control units are usually placed in a closet or out of
view. They need electrical outlets nearby and use large plug-in
transformers for the control unit, motion detectors, and sometimes smoke
detectors. So you can have 3 large transformers to plug in plus may also
want an outlet to use in the room. I would install 3 separate single gang
outlets so you have plenty of room for any transformers.

You need an incoming and outgoing phone line direct to your phone drop [to
the main control]. This is so the alarm can disconnect the inside phones
and have exclusive use of the phone line. (and no one could pick up a phone
to keep the alarm from dialing out.) 8 conductor cat 5 would do fine for
this. (Need 2 wires incoming and 2 wires outgoing.) So phone goes to
outside drop, then to alarm control, then back to drop, then to rest of
house.

For fire smoke detectors(usually part of the alarm system), special fire
rated fire wire is used. New code may require smoke detectors inside and
outside bedrooms, and other places. (Check with your local fire department,
alarm company, and electrical inspector to see what your options are.)
Regular interconnected smoke detectors may be able to connect to your alarm
system? Depending on the type of smoke detector used, you may need 120 VAC
at each detector, or for other types 12 VDC power plus the fire wire for
sending the alarm to other detectors and/or your alarm system. Garages and
storage rooms usually get a "rate of rise" detector which needs no power,
but needs the fire wire. These are set off by a rapid heat increase or an
extreme temperature. They have a barometric chamber/sensor and a small
pressure relief opening. If the temperature slowly goes up, air bleeds out
and the sensor does not trip. If temperature goes up fast, air can't bleed
out fast enough, and the pressure increases inside the chamber which causes
the sensor to trip.

"Pressure mats" can be placed under carpeting. Usually at a key point like
hallway. May want to run wire to baseboard at this location.

Motion sensors need 4 wires (two for DC power). Better to use 6 or 8
conductor for long runs so wires can be doubled up for DC power (DC Voltage
drop). Motion sensors are usually mounted near the ceiling in a corner, and
usually in living room and/or hallway.

Inside detectors, mats, motion sensors, etc. have the option of being
turned off while inside the house. Newer alarms can be set to turn on
everything or bypass the interior stuff for when you are inside at night.
Or you may want a switch on a wall somewhere. If you want a by-pass switch,
run a 2 conductor minimum wire to that location. (It can be a toggle switch
or an electrical key switch.) If pets are left inside, you want to be able
to turn off the inside stuff. This wire could go to a multiple contact
relay which would still allow inside devices to be on separate "zones".

Also run a separate wire from each sensor, door, window, to the control
unit. Some controls can have many separate "zones" and will tell the
monitoring company which sensor tripped the alarm. This is good for trouble
shooting if having false alarm problems. (Some alarm companies run wires
from window to window. Then when the alarm goes off, you only know that a
window tripped the alarm, but not *which* window or which set of windows.)

Also check each and every wire before the drywall goes up. It is not
unusual for wires to get cut while other work is being done.

If you live in a lightning prone area, note that all that wiring can pick
up voltage via inductance. All going to that control unit. May want
shielded wiring or you can use relays (tough as nails) to isolate the house
sensor wiring from the sensitive electronics in the control unit. Older
local alarm control units were all relays and no transistors/IC's. Very few
problems with lightning on these older units.

A vibration like someone pounding hard on your door can make a door sensor
very briefly open the contact (fraction of a second). An electronic control
unit will sense this brief open circuit, where a relay will stay closed
unless the sensor stays open for about a second.


"John Smith" wrote in message
Thanks for your help (and others, too). I visited your and other sites
mentioned in this thread, and I wish I could do a DIY. It looks like the
most fun anyone could have (I am an electrical engineer by education, and
a
S/W engineer by trade). The problem is, I am about 250mi away from my
new
house, and will be for the next few weeks , and I can't delay the
finishing
of the house without getting into a domestic battle.

I am meeting with the builder on Tuesday, and I will ask for the schedule
to
see if it is possible to fit myself into it .

To summarize what I gained through the net-wisdom:
1. Design a wiring closet in a secure location. Since I am already
planning
to have a home network and file server, and I can use CAT5 cables for the
security system, then I only need to have additional CAT5s for the
security
system. Does it matter if I use stranded or solid CAT5?

2. Call around for an installer who does this for a living (I-zheet
M'drurz,
take notes ) and willing to do the pre-install only. Most likely I
will go
with the original installer when the time comes anyway, as long the fees
are not
outrageous (again, I-zheet M'drurz, take notes ).