Door/Window contacts - Types and Brands

[ecborgoyn]

An EOLR at the panel might have a very small value over no EOLR in the loop. But this value might be out-weighed by the risk of extra splice(s) at the panel. Plus just managing the extra 'stuff' at the panel adds to the risk (risk of physical or electrical damage). Yes there is a risk of damage when installed at the EOL, but these wires don't move much after installation....

Do folks place EOLR's at the panel on fire loops also? A bit different scenario as these are supervising an open loop. And an open type fault in a conductor/connection is MUCH more probable than a short type fault.

As Lou says, place all of the EOLR's at the EOL.

 

[apostolakisl]

IMO, your just a fool not to use eol relay and eol resistor (at the actual end of line) on a fire loop. It would be so easy for a loose connection to render your fire system inoperable and you would have no idea.

Just curious, what would the "very small" benefit of an eol resistor mounted at the panel? The only benefit I can think of is the the reduction in amps output by the panel, is that what you are referring to?

 

[ecborgoyn]

Lou,
Good question.

Here's my logic: The resistor placed somewhere in the loop protects against some types of zone input channel failures/faults. With the loop closed and the resistor in the loop, the zone input channel would be measuring the EOLR value (probably measuring the voltage while using a constant current source through the loop). The input channel can fail in lots of ways. The desire is that ANY input channel failure results in a zone 'trouble' condition or zone 'violated' condition. It is unsafe for an input channel failure to result in a zone 'closed' (or non-violated) condition. I claim that the existence of the resistor somewhere in the loop improves the system 'reliability'. With the resistor, the only way for the zone to indicate the 'closed' or 'non-violated' condition is for the input channel to read the EOLR value (within some tolerance). Without the resistor, there are MORE plausible failures of the zone input channel that would NOT indicate 'trouble' or 'violated'. In other words, requiring that the loop have some specified resistance to indicate 'closed' is safer than having a short (about zero ohms) indicate a 'closed' state.

In short (pardon the pun...), the resistor in the loop, but at the panel, would NOT protect against wiring faults, but it would still protect against zone input channel faults.

In a past life I worked in nuclear power plant instrumentation systems (including the Class 1E protection systems responsible for 'tripping' the reactor to a safe state). One needs to look at faults/failures of all components in a system. Some of our protection systems went to extreme measures to protect against failures. For example, instead of using simple binary logic signals we would create specific pulse trains to indicate digital state. This would help to protect against the 'stuck on' or 'stuck off' types of fault conditions.

I hope this helps explain my 'very small' benefit statement. Please feel free to refute my claims.

 

[Del91574]

Do folks place EOLR's at the panel on fire loops also? A bit different scenario as these are supervising an open loop. And an open type fault in a conductor/connection is MUCH more probable than a short type fault.

Depends on how it's actually wired, per se. If installed across the zone terminals itself, it does nothing for supervising the wiring, and while most seem to care little about code or liability, it's a violation. If you wire the circuit as a form A loop with a feed and return, you can install the EOLR at the panel across the returning zone wiring and maintain proper supervision.

I'm curious about your examples, as I've never seen an alarm panel act as you state, PLC's and other controllers, yes, but I'm missing how your example would really work with the hardware I know and work with.

As far as installing an EOLR in series at the panel, I'm missing what you're saying because in the case of a digital controller, that's one item, but a ITPR (in the panel resistor) does nothing to supervise an input failure if the input itself bridges to ground via the enclosure or via field wiring failures. A circuit board failure may or may not cause a panel to view a zone as open, but generally, once the EOLR tolerance and zone tolerance are added in, it's not the same as control wiring on a digital controller. An input may fail, however it's still going to be an open circuit, or if the wiring bridges within tolerance, it's still not a change that would exceed a trouble threshold on most panels I know of.

Explain further?

 

[Sandpiper]

If we are to have another EOL discussion, please start a new thread so I can ignore it again......

 

[ecborgoyn]

I stripped the insulation back on the one lead so that when slipped into the screw terminal of the contactor none of the non-insulated wire showed. Then I cut the resistor wire back so that when it was fully inserted into the other screw terminal the body of the resistor ended up just touching the contact and tightened it into place. Then I cut the other lead from the panel back so that it dead ended just shy of the resistor. Then after stripping 1/4 inch from alarm panel lead, I wrapped the resistor wire around it a bunch of time. Then solder. Then I wrapped with a couple wraps of electrical tape both wires/resistor together. No need for insulation between the two wires because of the way I did it. You could also use the shrink wrap instead of electric tape for a slightly cleaner look.

Putting it together this way was very solid since the two wires/resistor were all bundled together creating a lot of stability. I also had 18g alarm wire which helps with robustness.

Thanks for the detailed explanation of your EOLR installation method at the contact. I think I will go with the screw terminal contacts as they seem to make life so much simpler. Plus Your scheme of butting the body of the resistor against the contact (and then taping) also helps with my concerns over strain relief and possible breakage of the resistor leads. The resistor and contact are rigidly held together by the tape, or perhaps heat shrink tubing.

 

[apostolakisl]

The resistor and contact are rigidly held together by the tape, or perhaps heat shrink tubing.

No, you can't take the tape over the contact because it won't fit into the hole. They are just slightly tapered so the 3/8 model is only slightly less than 3/8 inch at the very end. The rigidity of the resistor comes from being secured to the adjacent wire. The heavier your wire gauge the more rigid. I used 18 gauge wire and it is very rigid, probably a bit overkill.

But, it really isn't that big of a worry because it is a one-off deal. Once you put it in the hole, it is likely it won't be touched again for decades. So if you treat with just a little respect as you slide it in, all should be fine.

 

[ecborgoyn]

Explain further?

I'll focus on the closed loop intrusion detection circuits. Everyone agrees that EOL resistors and EOL power supervision relays are needed for fire and other life-safety detector circuits.

Regarding intrusion detector circuits (closed loop). The goal should be a fail-safe implementation. 'Safe' states are either 'Trouble' or 'Violated'. Agree so far? A non-safe state would be 'Non-violated', or loop closed... Agree?

All that I'm saying (to answer the question posted) is that having a resistor SOMEWHERE in the detector circuit (loop) make the implementation more 'fail safe' than without a resistor. Even without knowing the design of the zone input channel, I CLAIM that it is better with the resistor as then the only safe state of the circuit would be to read the resistor value (within a tolerance). Without the resistor in the loop, an input channel can fail such that it reports the looped closed condition, which is a non-safe failure. I CLAIM that it's more difficult for an input channel to fail in such a manner that it reports some particular resistance in the loop. Hence more channel failure scenarios would lead to a safe state ('trouble' or 'violated') IF there is a known resistance in the loop.

Think of the channel/loop condition and what is reported. Introducing the resistor and defining it's value (within a tolerance) as the only non-safe state of the circuit you inherently increase the number of safe states. So more input channel failures would lead to a safe state reporting. It the same story as with the loop wiring, just pushed back into the input channel.

I'm NOT discussing WHERE this resistor is located in the loop... That's a separate failure analysis. I'm ONLY addressing whether or not there is a resistor in the loop...

Enough said... Sorry for hijacking my own thread.... I'm putting EOLR's at the EOL.

 

[ecborgoyn]

No, you can't take the tape over the contact because it won't fit into the hole. They are just slightly tapered so the 3/8 model is only slightly less than 3/8 inch at the very end. The rigidity of the resistor comes from being secured to the adjacent wire. The heavier your wire gauge the more rigid. I used 18 gauge wire and it is very rigid, probably a bit overkill.

But, it really isn't that big of a worry because it is a one-off deal. Once you put it in the hole, it is likely it won't be touched again for decades. So if you treat with just a little respect as you slide it in, all should be fine.

Yes, I understand. I was thinking about my own contacts while I was typing. All of the 3/8" contacts are actually installed in 3/4" holes in the window frames with 3/4"-3/8" adapter "donuts"... So I have much more room to work with.

Thanks.

 

[fresno51]

How to connect door/window switches...page 5:
http://www.elkom.com.tw/m/PLC2011A0_PLC2011B0_PLC2011C0_circuits.pdf

 

[BraveSirRobbin]

FYI, here is a schematic showing how and why EOL's are most efficient when mounted at the contact sensor.

Myself, I just don't use them. If you are careful and thoughtful when running your wiring and terminating your connections, I (as well as many others) see no use for them in a residential installation.

 

[video321]

FWIW... I took Spanky's advice that not using an EOL gave a better transient tolerance.

 

[gizzmo]

I think the above diagram is flawed, if it doesn't show the positive and negative side of the circuit, then the author doesn't fully understand how the circuit functions. Other than that it is correct. It can make a huge difference if there is a ground, which is more likely than a short in my opinion.

Sent from my Galaxy Nexus

 

[BraveSirRobbin]

I think the above diagram is flawed, if it doesn't show the positive and negative side of the circuit, then the author doesn't fully understand how the circuit functions. Other than that it is correct. It can make a huge difference if there is a ground, which is more likely than a short in my opinion.

Not sure I understand what you mean. You want to see a pos and neg at the panel on that diagram (that really doesn't make a difference)?

 

[gizzmo]

Not sure I understand what you mean. You want to see a pos and neg at the panel on that diagram (that really doesn't make a difference)?

If you place the resistor in the panel on the positive side of the circuit any ground will make the circuit complete. If it is on the negative side a ground will cause the circuit to show as a short.

Sent from my Galaxy Nexus