Electronic Alarms and Home Security Devices - EOL Reisitors and Smoke/Fire Detectors

With advice from my previous post, it sounds like the ADEMCO Vista20P may be right for my DIY installation in my new home. I'm not experienced at fire alarm installation so I need a bit more advice.

Being an EE, I undertstand the need for a resistor to supervise the health of a system and prevention of tampering. If it's called an "End of Line" resistor, why are some folks advocating installing it at the head of the circuit in the panel? Are resistors typically installed at "the end of the line" where the contact is? If so, do you simply splice them in series?

Also, there are many different smoke and fire detectors available. I need some guidance as to 2 wire vs. 4 wire, integral sounder, and if special wire is needed for fire/smoke detectors.

One other thing....are there any recommendations on placement of smoke and fire alarms (i.e. each room, general areas, attic, etc...)

Thanks to all in advance. This forum is really handy.

Big Lug

Security circuits are normally closed loops. In an ideal world, every circuit would have a single normally closed contact with a supervision resistor in series at the contact end of the wiring. In the real world, homes are often prewired with normally closed contacts that are often not accessible, or installing the resistor directly at the contact would be unsightly, and you usually have to connect the individually homerun alarm loops into a zone groupings.

In a residential system, the odds of zone wire tampering are insignificant, so essentially converting the loops to plain NC loops by installing the resistor at the terminal end is not an issue. Several of the major brands allow simply turning off the requirement for supervision resistors.

_Fire_ loops are another breed of cat. Nearly all fire alarm devices are normally open devices, so you have to wire from device to device, and you absolutely _should_ put the resistor on the last device in the chain. Even on systems that allow disabling the resistor requirement, when you set a zone as a fire zone, you still have to install the resistor.

On the rare instance that you are installing a single detector on a fairly short loop, and you are diligent in your maintenance and testing, I would feel less uncomfortable suggesting putting the resistor at the head end of the circuit, but it's still a bad idea.

If your hardware supports 2-wire smokes, use 'em. Much simpler to deal with.

Integral sounders are a personal/AHJ choice. In N. FL, it is perfectly acceptable to simply use the security system sounder in a residential setup, as long as it produces a distinctive sound for fire alarm, and the siren circuit is supervised. Some areas require individual sounders on each detector with interconnect sounding. Your mileage may vary.

For a proper fire loop, 18 gauge is the minimum. It's what NFPA, UL and the device manufacturers specify.

I can just answer on the locations of the smokes since I am not a pro at installing them into a panel.

Chapter 8 of NFPA 72 requires smoke alarms to be installed outside each separate sleeping area and on every level of the home. In new construction, smoke alarms are also required in every sleeping room. Detectors must be 120 vac powered with battery backup in new construction, but may be battery powered in existing construction.


Saying this, it doesn't mean you have to comply, but if you have enough money to get all the required detectors, do it. Installing 2-4 wire/wireless smokes to your alarm panel usually fulfills the requirements of the code, but ask your local Fire Dept/Chief to be sure.

If installing on the ceilings, do not have the detector 4" or less away from a wall. If mounting on wall, do not have the detector 12" lower from the top of the wall.

Thanks for all the great advice. I was beginning to wonder if I was going to get a reply. As a follow up, I understand that the fire alarm wire has a red jacket? Can I just pull it to a single gang box mounted to a ceiling joist during rough-in?

The EOL thing makes sense from a residential tampering standpoint (not likely unless you have some very crafty teenegers).

Lastly, I plan to run each smoke/fire on it's own zone if you guys think that would be a good idea. I think the Vista 20P should have enough zones available to do what I want to do (3 doors, 6 windows, 7 smoke/fire). At $50 each, 7 smoke and fire could be costly.... I know it won't be as costly as not having them in the event of a fire.


T.H.

The only way to run that many smokes on individual zones with a Vista panel is to use 4 wire smokes; a much more complicated installation job, overall. Only zone 1 on a V-20p supports 2 wire smokes. Unless the house is huge, you can tell which smoke is active because the red tell-tale latches on until the smokes are reset.

"Fire wire" can come in any color. What makes it fire rated is the composition of the plastic in the insulation (it's treated to be fire retardant). _Most_ commonly found fire wire does have the red coat.

You can just run it into a junction box. It needs to be secured to the joists and studs, just don't get overly aggressive with any staples or clamps. The insulation is much softer than average NM cable.