Door Sensors

[Quixote_1]

What's up with the ratings on these things, anyway? If you recess one into your door frame, I can see the potential for compromising the lock and opening the door by a fraction of an inch, then placing a strong magnet in the vicinity of the reed switch. Most of them are rated at least 3/4 of an inch. That is a lot of leeway, even if you place the sensor right at the opening end of the door. You don't need to be a genius to figure this out... maybe just an observant gardener or maid.

 

[KentDub]

The real reason for EOL resisters is not because of a skilled thief. Its that the EOL resistors assure that the wiring is good. You'd be surprised over time how many wires get pinched or melted together. Without a EOL resistor AT THE SENSOR you would never know this. They are there for a reason, so just use them like they were intended.

As for sensors, magnetic ones use glass sealed reed switches which are VERY reliable when used correctly. You want the magnet to move toward and away from the sensor, NOT slide across. The sliding can magnetize the sensor over time. I'd stay away from plungers for alarm sensors. They get lots of dirt in them and don't last very long. Magnet sensors installed correctly are your best bet.

So I should just use the resistor and jump the two terminals of the sensor? I shouldn't pigtale them? Seems one less splice in the cable makes it that much more reliable.

As for sensors, magnetic ones use glass sealed reed switches which are VERY reliable when used correctly. You want the magnet to move toward and away from the sensor, NOT slide across. The sliding can magnetize the sensor over time.

How is this possible with a hinged door? It seems that the only way that works is if you install it on the hinge side (which to me, at least how I visualize it, would allow a door to be ajar but still register as closed because of the gap the sensors allow). What is the duration of the magneticization (is that a word?) months? years? The wired sensors are so cheap it wouldn't be a big deal to replace them every 3-5 years.

Thanks,
Kent

 

[ano]

The real reason for EOL resisters is not because of a skilled thief. Its that the EOL resistors assure that the wiring is good. You'd be surprised over time how many wires get pinched or melted together. Without a EOL resistor AT THE SENSOR you would never know this. They are there for a reason, so just use them like they were intended.

As for sensors, magnetic ones use glass sealed reed switches which are VERY reliable when used correctly. You want the magnet to move toward and away from the sensor, NOT slide across. The sliding can magnetize the sensor over time. I'd stay away from plungers for alarm sensors. They get lots of dirt in them and don't last very long. Magnet sensors installed correctly are your best bet.

So I should just use the resistor and jump the two terminals of the sensor? I shouldn't pigtale them? Seems one less splice in the cable makes it that much more reliable.

As for sensors, magnetic ones use glass sealed reed switches which are VERY reliable when used correctly. You want the magnet to move toward and away from the sensor, NOT slide across. The sliding can magnetize the sensor over time.

How is this possible with a hinged door? It seems that the only way that works is if you install it on the hinge side (which to me, at least how I visualize it, would allow a door to be ajar but still register as closed because of the gap the sensors allow). What is the duration of the magneticization (is that a word?) months? years? The wired sensors are so cheap it wouldn't be a big deal to replace them every 3-5 years.

Thanks,
Kent

It depends upon the panel, but TYPICALLY EOL resistors are installed IN SERIES with your sensor, not parallel. I wouldn't worry about reliability, it will be reliable. Lets say your EOL resistor is 1000 ohms. When the door/window is SECURE, the panel will see 1000 ohms plus a bit for wire resistance. When the door/window is NOT READY, it sees an open connection. If it sees a resistance far under 1000 ohms, that's a fault, and indicates a problem.

On the sensors, its up to you as to the kind, but professionals rarely use non-sealed contacts anymore, like those in those push-button style sensors. Yes, even they only may fail after 5 years, but most people don't want to have to replace these every 5 years, nor experience the alarms a faulty sensor causes. Magnet switches typically are installed at the opening side, not the hinge side.

 

[Photon]

Since you have an Elk M1G, I recommend you take a peek at the Installation and Programming Manual, para 1.4 "Control Wiring," where you will find diagrams and explanation of zone wiring with EOL resistors.