more clarification

Should I be installing EOL resistors in at all my contact points? I have 1 sensor per zone. Are EOL's the prefered method? If so, the manual shows the circuit as positive wire coming out of zone input, to resistor, to contact back to neg of the controller, all in series.
 

Guy Lavoie

Active Member
Normally, you need one EOL resistor per zone. If this is for a non-critical application like detecting a home automation event, then you can put the resistor at the panel to keep the remote wiring simple. For a more critical application like a burgular alarm zone, then you ideally want the EOL resistor at... the end of the line, to gain the advantage of the circuit integrity verification that it provides.
 

AutomatedOutlet

Senior Member
Yeah, I agree with Guy.

But, most people can't get to the end of line... So, if you have a panel like the Elk panel, you can just set it up without EOL resistors. There really is no point in installing them at the panel ;) .

I have installed 2 Elk panels at this point. One for my office and one for my house. I didn't use the EOL resistors in either place.
 

upstatemike

Senior Member
But, most people can't get to the end of line...

Martin, I'm not sure I understand what you are saying here. If someone can't get to the last device on a zone, how did they install it in the first place?
 

AutomatedOutlet

Senior Member
What I'm saying is that if the walls are already closed, it's touch to open them up to put resistors at the end of the line (at the door or window).
 

upstatemike

Senior Member
I guess I'm having a bad day cause I still don't follow you. Even a recessed contact is installed with enough slack so it can be pulled out for service or replacement if needed. Why can't you just pop out the last contact, add a 1/4 watt resistor (which will fit in behind even 1/4 inch recessed conacts) and pop it back in? I can't picture where opening the walls comes into the picture.


edit-
I should also make clear that I am not being critical here. I don't have any feelings one way or the other on end-of-line resistors on alarm panels. I really am just curious.
 

BraveSirRobbin

Moderator
upstatemike said:
Even a recessed contact is installed with enough slack so it can be pulled out for service or replacement if needed. Why can't you just pop out the last contact, add a 1/4 watt resistor (which will fit in behind even 1/4 inch recessed conacts) and pop it back in? I can't picture where opening the walls comes into the picture.
In my case there was insluating foam that was sprayed around the windows, making the depth of the opening for the sensors very limited. It was hard enough to try to stuff the wire back in the hole, let alone deal with a resistor.

This also happened on my buddy's house when we installed his security system. It was hard to push the wire back into the mounting hole (even though we kept the slack to a bare minimum).

Of course the "ideal" situation is to do all of this before drywall is up, then everything is a non-issue because you can get to both ends of the wire (running through the window frame/stud). But, when you are trying to do this with the only access being the exterior hole for the sensor, it would be a very difficult task.

Of course I have a whopping TWO security installations under my belt (but then again I'm two for two when dealing with this issue ;) ).
 

bfisher

Active Member
... the Caddx security system requires 3.3kohm EOL resisters. To fit the resister and connectors behind the sensor is sometimes tough. I've managed to make it work every time (existing home), but sometimes it's difficult. Usually I end up taking off the molding around the door/window so I have room to work.
 

upstatemike

Senior Member
I think the connectors are the big challenge. Even b connentors take up too much space. For an EOL resistor I would probably solder the connections and insulate with a dab of silicone.
 

BraveSirRobbin

Moderator
upstatemike said:
I think the connectors are the big challenge. Even b connentors take up too much space. For an EOL resistor I would probably solder the connections and insulate with a dab of silicone.
Yes, this is one good suggestion! Another may be to just solder the wires and use shrink wrap over the entire assembly.
 

pmonahan

Member
First a note about End of Line Resistors; they are named because of their placement on the circuit. They should go at the end of line if you desire a supervised circuit.

If the resistor is installed in the panel , then short circuits in the main run on a Normally Closed circuit will never be detected (A window zone that rarely opens for exaple) could be shorted for days, weeks or years without your knowledge and then fail when needed.

This happens more frequently than you would think because of staples and otherwise pinched cables.

Knowing the correct way, you have to make a decision what you'd like to do.

One way to overcome the issue of concealing the resistor at the end of the line is to use the 3/4" press fit switches with a 3/8" magnet. You can bore the hole for the switch deep enough to hold a service loop of wire AND the end of line resistor.

I've never been fan of 3/8" switches because they encourage improper installation of the EOLR.

Always use gel filled connectors, especially on perimeter doors as the single biggest point of failure is where the splices are located; they usually corrode after 1-2 years, building enough resistance to cause run-away troubles.

Normally open circuits are better for motion detectors and of course fire alarm circuits because the panel detects: Normal, Short, Open, & Ground whereas the Normally Closed Circuit really only detects Normal, Open and Ground. In this regard you can monitor the tamper switch of a motion sensor separately from the Alarm Contacts.

If you install the resistor in the panel on a Normally Open Circuit, you effectively have no supervison of field wiring.

Thanks

Peter
 

upstatemike

Senior Member
If you plan ahead, couldn't you run 4-conductor on your zones and use the second pair as a return back from the last device? This way you could have the end-of-line resistor NEAR (not in) the panel and it would still truly be the end of the line. Might be handy for troubleshooting.
 

pmonahan

Member
Mike,

Good thought....at that point you have what's called a "Class A" circuit and the return wires would connect to the return terminals on a "Class A" Panel. Class A circuits are such that any <b>Single</b> open, or ground will not prevent the alarm from being transmitted.

This was very common on UL Listed mercantile alarms and of course Fire Alarms at one time.

However, most panels (like the Elk) are Class B Panels; they use end of line resistors.

Once you get a few under your belt, installing the End of Line resistors at the switch is really not that bad; especially if you use the 3/4" switch.

Thanks

Peter
 
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