Electronic Alarms and Home Security Devices - End of line Resistors

I am installing a new DSC PC1555 system. I know that it is an option to use the EOL resistors. But what is the difference? Also in one room I have a motion detector and a glass sensor. I can wire the sensors in series for one zone but do I need an EOL Resistor?

The main advantages of using the resistors is that it "supervises" the circuit, and allows you to mix normally closed and normally open devices on the same loop. When properly installed, they can keep multi device circuit from being partially disabled.

That said, in the typical residential installation, especially in a prewired structure, the unsupervised method is very common (even in systems without the means to turn off the resistor requirement, installing the resistors at the panel terminals is the functional equal).

A lot depends on how likely you are to have to worry about a theif that knows enough to try and defeat the zone wiring. Most can't, and won't try.

I primarily do commercial installations, so I generally install them at the device end of the wire.

One more thing. How many sirens can I hook up? The manual mentions one, but I have one that mounts to the wall and I want one in the attic as well. Can I hook these two up in parallel? Also the interior DSC siren that I have has two red wires, two yellow wires, and a single black wire. I know that the black is common and the red's and yellow's are for yelp and steady. But why two wires for each? Is it to string another siren from?

You can wire multiple 12v sirens as long as they don't add up to more than the current draw limits for the siren terminals (about 1 amp, I think). Without seeing the install sheet for this siren model (and knowing the model), I couldn't tell you what the doubled wiring is for without guessing.

There isn't any install sheets with the siren. The only thing that I have is inside there is a sticker telling what the wires are for. Looking at the wiring, they do connect to the same trace on the circuit board. It's just odd that they wired it that way. By the way it is a DSC siren.

There are a number of ways to configure a 12v siren for multiple effects. For whatever reason, DSC prewired theirs for flexibility (usually you have to make a split pigtail for some of these tricks. You could, in fact, use the common and the unused lead of a given pair as a pickup point to extend to another siren.

As long as the current draw in is within limits, and the wire gauge is large enough for there not to be an excessive voltage drop, you should be fine.

MrRonFL,

Would the sirens be wired in parallel or series ? ?

Wire them in parallel. You are providing 12volt power to a self-contained sound generator.

Thank you !