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Interlogix NX-8v2, Double Zoning

ecm1949

Nov 22, 2021
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I have a NX-8v2 Security System and want to know if I use the double zoning feature will I need to change all the EOL resistors. I wanted to add only two zones so if I turn on zones 9 and 10 only in Location 28 and change those resistors will the other zones be effected if I do not turn them on.
Can someone please help?
 

ChosunOne

Jun 20, 2010
480
Joined
Jun 20, 2010
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emc 1949, first I have to warn you that, although I have around 40 years of experience as an alarm tech, working with over a dozen different professional-grade brands (nearly all of the major brands in North America)---by some quirk of fate, I've never worked with the Interlogix brand. My guess is that they just aren't marketed big in the D.C. Metro Area, compared to the other Big Brands.

I've looked over the installation manual and I want to say that turning on only zones 9 & 10 in section 28 will not affect any of the other zones you aren't trying to double, as long as none of the 4 doubled zones is a Fire Zone. In other words, you won't need to change any resistors except those necessary to enable 9 & 10 as doubled zones.
HOWEVER: I recommend you re-post your question in this forum:
https://www.doityourself.com/forum/electronic-home-security-systems-alarms-devices-87/
And get your answer from a tech who actually has hands-on experience with Networx panels.
 

ecm1949

Nov 22, 2021
8
Joined
Nov 22, 2021
Messages
8
Thank You for the information. I gave it a try by turning on the double zoning feature. All zones except zone 8 which is a fire alarm have a 3.3k EOL resistor. The zones 9 & 10 have a 6.98k EOL resistor. According to the manual it calls for a 3.74k on the lower zones when doubling. I went to Location 28 and turned on the first two zones which gave me zones 9 & 10. I dont know if all the zones 1 thru 8 are doubled when you dont turn them on. Zone 8 is a 2- wire smoke detector. It shows OK and the light on the detector is still flashing green.
So you are right, it did not affect the other zones 3 thru 8. They seems to work OK, I tried it and have no issues with it yet. I just want to do it right and have no problems later with it. Should I change the 2 lower zones I doubled from 3.3k to 3.74k or just leave them since its working?
Thank You!
 

ChosunOne

Jun 20, 2010
480
Joined
Jun 20, 2010
Messages
480
Follow the Installation Manual instructions, and put 3.74K resistors on the lower zones. There's a reason it directs you to use 3.74K resistors.

I don't know what tests you ran to ensure it's "working", but I assume everything "worked" as expected---but it doesn't matter. A zone can "work" when its resistance is 'way more or less than it's supposed to be, and manufacturers won't tell you what the tolerances may be, and for good reason: Installers aren't supposed to be trying to see how much they can get away with, they're supposed to be installing the resistance values prescribed in the manuals.

One memorable example of this comes to mind, from years ago: A couple of installers upgraded a home system from one panel that used 3K zone loop end-of-line resistors (EOLRs), to a panel that used 2K EOLRs. Now, it's not unusual for the "EOLRs"--i.e., the "End of Line Resistors" that the manufacturer says should go at the end of the zone loop--it's not unusual to install the burg(lary) zone EOLRs on the Panel, the main PCB board, at the beginning of the zone loop.
(There is difference of opinion in the alarm tech community whether this is acceptable practice, but I'm in the camp of installing home alarm burg zone EOLRs at the panel, for reasons I'll discuss with anybody who's interested; but it's not relevant here.)

So the installers switched out the Control Panel and keypads, including switching out the 3K resistors at the Panel for 2K resistors, as prescribed---but the reason I mentioned the burg EOLRs at the panel is that Fire Zone EOLRs NEVER go anywhere except at the End of the Line--the last fire sensor (smoke sensor or heat sensor) on the fire loop. That is not disputed among techs, and it's illegal according to Fire Code to install it anywhere else. It would be worth prison time for me to put it at the panel.

But switching out the 3K on the fire zone for a 2K would have cost the installers a lot of extra time and effort, because the smoke sensor at the end of the line was high above a narrow landing three flights up a staircase. The rest of the upgrade had been in comfy eye-level conditions,but switching out the Fire EOLR would entail wrestling a tall (15') stepladder up 3 flights of stairs, setting it up on a precarious landing (if you've ever stood on a tall stepladder where you're looking down 3 stories, you'll know what I mean.) and having your buddy steady the ladder while you do the switch. He better be someone you trust.

But--oh, joy!-- When they connected the fire zone with the existing 3K resistor and powered up the panel, it indicated that it was 'happy' and Ready to Arm (green light). The Keypad showed no trouble on the Fire Zone! I.e., it "worked." The new panel tolerated it. So they packed up and left. Job finished.

The reason I know about that job is that I'm the service tech who was sent there three days later to figure out why the system had had a false Fire Trouble Alert in the middle of the night before, and now the fire zone wouldn't reset, even though there was no smoke. I found the cause pretty quickly, and I had to haul that tall stepladder up those steps, set it as stable as I could get it on that narrow landing (which wasn't wide enough to open it fully), and climb up it with no buddy to steady it (installers tend to work in pairs; service techs usually work alone.) Fortunately, I climbed a lot of trees as a kid and did some sport climbing when I was older; heights don't bother me, and I'm pretty steady on a ladder, even when I have to have my head craning up looking at the smoke sensor I'm working with. For awhile I kept the 3K resistor for a souvenir.

I don't usually tell 'war stories' except when talking shop with other techs, but I want to impress you with how tolerant a system panel can be about EOLRs---until it isn't. That panel--it was an Ademco--tolerated a 50% higher-than-prescribed resistance on its fire zone for TWO! DAYS! before it decided to object to it. This isn't a flaw in system design, IMHO. Alarm systems have to have a certain tolerance, because the environments of the various zone loops can sometimes throw a lot of transient fluctuations at them. (That's a lot of other stories that I'm happy to drone on about if anybody's interested.)

The zones have prescribed resistances that the panel monitor--with your panel, it's 3.3K Ohms for single zone, and you could probably get away with a 3K or 3.6K if that's all you have---but switch it out for the proper resistor as soon as you can. Yes, it will "work" with an over/under value, but it won't really be happy with it, and will be less tolerant of other transient conditions the loop may encounter, e.g., a nearby lightning strike.

Outside of Zone Doubling, a panel "looks" for either an Open or a Short on the loop--either 'infinite' resistance or 'zero' resistance. It's only with Doubled Zones that it discriminates between set resistances other than Open or Zero. And under certain conditions--like if you have a flaky connection that pushes the limits of tolerance--it can get confused which of the doubled zones has a problem. I recommend you do a good job soldering any and all splices and be meticulous about making tight connections at screw terminals and such. And use the resistors prescribed!

PS: For what it's worth, I'd recommend you put your 'EOLRs' at your NX-8V2 panel--it makes any future troubleshooting a lot easier. Also, just to let you know, your Interlogix panel has recently (2019) been 'orphaned'---i.e., the company that made it decided not to stay in the alarm business. So you (or someone) will be looking at eventually replacing it with another brand, which will probably entail switching out the EOLRs. Which is a major reason I'm in the at-the-Panel school of opinion, for home systems.
 
Last edited:

ecm1949

Nov 22, 2021
8
Joined
Nov 22, 2021
Messages
8
Hello Again
I understand what you are saying about the resistance tolerance in the zone circuits. I will change out all the 3.3k resistors with a 3.74k for zones 1 -7. I will leave zone 8 a 680 ohm because it is designated as a Fire Zone, in Location 37 Segment 6. If it were not turned on as a 2-wire smoke then I would change it too. The upper zones 9 - 16 I will put a 6.98k resistor on those zones. I am just not sure if the zones 11 - 16 that are not turned on are necessary to change. I would guess all the zones are doubled since that feature is turned on even though they are not selected in Location 28.

Example: My system says Ready to Arm. If I goto Location 28 and turn on Zone 11 that is not connected to anything, the Ready Light goes off. Then I scroll through my zones and all show OK except Zone 11 that shows Fault. That is correct. If i go back and turn that zone off again my Ready Light comes back on and Zone 11 does not show at all. So if I turn off a Zone it ignores it. When I add a Zone it will recognize it.

I know you were saying put the EOL in Control Panel instead of End of Line. because it is easier. The only thing is this system when Armed will sound an alarm if there is an open or short circuit. So if I had a short in the attic somewhere, the alarm would not sound because it thinks the door or contact is still closed with the EOL at the Control Panel.
 

ChosunOne

Jun 20, 2010
480
Joined
Jun 20, 2010
Messages
480
Whoa, wait! The first time I read your latest post (#6), I got caught up in other stuff and completely missed what you said about switching out the 3.3K resistors resistors for zones 3-7, and also adding 6.98K resistors to each of those zones.

Don't do that!! Burg Zones that are not doubled should have 3.3K resistors in series in the zone loop.

Zone doubling is turned on zone-by-zone. Since Zone 1 and Zone 2 are doubled, Zone 1 becomes a lower zone and Zone 9 is the "twin/paired" upper zone; Zone 2 becomes the lower zone and Zone 10 becomes the upper zone. Zones three thru 7 are simply zones: No upper or lower, 'cause they're single zones. They (3-7) retain their 3.3K resistors.

If you've already configured the zone 3-7 EOLRs as you mentioned, you will have noticed that the Panel didn't explode, the universe didn't implode on itself, the crops didn't wither in the fields, the milk didn't sour, and there were (probably) no earthquakes in your vicinity. That doesn't mean it's okay to do that!
The single zones will "work" with paralleled 3.74K and 6.98K resistors because, with the door(s)/window(s) closed, that pair comes close to a 3.3K resistance, within tolerance of gold-band resistors--however, the Panel, on single zones is looking for 3 things: Open circuit, dead short (near-zero resistance), or 3.3K, (plus or minus unspecified tolerance) Ohms. If the zone isn't doubled, and you have a 3.74K resistors in series with your detector(s) on the zone loop, then to make the Panel happy, you must have a installed the 6.98K resistors in parallel with the zone loop. Which means that when a door or window on any of said zones opens, the Panel sees 6.98, i.e., about 7 KOhms, on the loop---which will probably, being a much higher resistance than 3.3K, be seen as an open (and I reiterate that I'm guessing here, and am not familiar with this Panel) and the zone will (probably) seem to "work" normally---at least most of the time. It "working" today doesn't mean that it will tomorrow---that is only predictable if you use the proper resistors for the zones as prescribed by the manual!
-------------------------------------------------------------

I know you were saying put the EOL in Control Panel instead of End of Line. because it is easier.

The reason I recommend putting EOLRs at the Control Panel, for home systems, is that it can make a lot of potential future problems easier to work with. The reason I specify home systems is that commercial and institutional systems need the EOLRs at the end of the line because of potential tampering from employees or customer-perps looking to circumvent the system.
In the first place, stores, warehouses, etc, tend to have a lot of exposed zone loop wires in public places and surface-mounted door/window sensors that can be tampered with in a few seconds of relative privacy. In the second place, they have a lot of casual traffic and you just can't watch everybody all the time. Installing resistors at the last sensor in a loop means you can't circumvent the loop by quickly twisting a pair of wires together, or clamping a short across sensor contracts.
Homes are a different story: With few exceptions, door/window sensors are recessed, not surface-mounted; and the wires connecting them are in walls, ceilings, unfinished basements, and attics; and not accessible to the general public or employees (unless you count household help, who are generally not a risk or they wouldn't be household help). You don't have a lot of customer traffic passing through your house--or if you do, then it's a commercial system, not a home system.
Now "easier to work with" can mean easier to troubleshoot if you ever have a problem with a zone. For example, if you have an "unexplained alarm" (aka a "false alarm"), one of the first things I check is resistance on the loop. Is it too high? (Should be only a few Ohms at most). Most importantly, is it steady, not fluctuating at all? But if the EOLR is at the end of the loop, a gold-band 3.3K resistor has a value of anywhere from 3135 to 3465 Ohms, a spread of 330 Ohms. The resistance is the loop itself is lost in that--you can't read it at the control panel. It's worse than trying to listen to music through heavy static.

The only thing is this system when Armed will sound an alarm if there is an open or short circuit. So if I had a short in the attic somewhere, the alarm would not sound because it thinks the door or contact is still closed with the EOL at the Control Panel.

Yes, it's true


The system when Armed will sound an alarm if there is an open on the loop, regardless of where the EOLR is. It's only with a short that supervision is limited or not, depending on how you install the resistor:
Yes, if a loop with an ATPR (At The Panel Resistor) is shorted in the attic--and only shorted--then the zone will stay "happy." But that's a circumstance that's vanishingly rare. Most alarm zone loops are carried in "quad" cable, 4 insulated wires enclosed in plastic sheath, a lot like household telephone wire.
The wires don't short spontaneously--the most common cause of a short is a staple shot thru the cable, or a drywall screw, or nail during the initial installation, which is found and fixed at testing; also during the installation.
The second most common cause is the quad or wire rubbing against something enough to wear through the wire insulation, nearly always metal water pipes or ducting. In that case, the wires can be shorted, but they are also grounded. Doesn't happen often, but it does happen. If you land (connect) the resistor in the panel on the gounded (low or negative) side of the loop, then grounding the loop creates a "ground fault" which will create a fault/trouble/alarm condition the same as an EOL short. (This assumes that the Panel is grounded, which it should be if it was installed properly.)
Squirrels, mice and rats can sometimes chew through wires in a attic, but that nearly always results in an Open, not a short.

I probably shouldn't even have mentioned where to place the resistors, but I've seen so many people set themselves up for a lot of grief they didn't need to endure. Most door/window sensors are 3/8" press-fit recessed contacts, many of which tend to wedge themselves into their holes so tight that you have to destroy them to get them back out, to work with contacts or splices, or change a resistor; and it makes changing out EOLRs a major chore. On top of that, the alarm industry is Balkanized in that every manufacturer uses different values for the EOLRs, for no good reason I've ever been able to figure out.
----------------------------------------------
One final recommendation: Re-post your questions on this specific alarm diy forum and get a second opinion from someone who has hands-on experience with your specific panel.
https://www.doityourself.com/forum/electronic-home-security-systems-alarms-devices-87/
 

ecm1949

Nov 22, 2021
8
Joined
Nov 22, 2021
Messages
8
I checked the other forum that you sent me the link to. Only got one answer, and that was to change resistors on all the Zones even if they are not used.
 

ChosunOne

Jun 20, 2010
480
Joined
Jun 20, 2010
Messages
480
Yes, I saw. That's why I asked you to post there. I've been reading MrRonFL's posts for about a decade now and he has a wider range of experience than I do. I'd follow his advice, and put the double-zone resistors on zones 1-7. I didn't study the NX-8v2 manual thoroughly enough to find that, since I wasn't actually working on one in front of me, and probably never will at this point.
 

ecm1949

Nov 22, 2021
8
Joined
Nov 22, 2021
Messages
8
Whoa, wait! The first time I read your latest post (#6), I got caught up in other stuff and completely missed what you said about switching out the 3.3K resistors resistors for zones 3-7, and also adding 6.98K resistors to each of those zones.

Don't do that!! Burg Zones that are not doubled should have 3.3K resistors in series in the zone loop.

Zone doubling is turned on zone-by-zone. Since Zone 1 and Zone 2 are doubled, Zone 1 becomes a lower zone and Zone 9 is the "twin/paired" upper zone; Zone 2 becomes the lower zone and Zone 10 becomes the upper zone. Zones three thru 7 are simply zones: No upper or lower, 'cause they're single zones. They (3-7) retain their 3.3K resistors.

If you've already configured the zone 3-7 EOLRs as you mentioned, you will have noticed that the Panel didn't explode, the universe didn't implode on itself, the crops didn't wither in the fields, the milk didn't sour, and there were (probably) no earthquakes in your vicinity. That doesn't mean it's okay to do that!
The single zones will "work" with paralleled 3.74K and 6.98K resistors because, with the door(s)/window(s) closed, that pair comes close to a 3.3K resistance, within tolerance of gold-band resistors--however, the Panel, on single zones is looking for 3 things: Open circuit, dead short (near-zero resistance), or 3.3K, (plus or minus unspecified tolerance) Ohms. If the zone isn't doubled, and you have a 3.74K resistors in series with your detector(s) on the zone loop, then to make the Panel happy, you must have a installed the 6.98K resistors in parallel with the zone loop. Which means that when a door or window on any of said zones opens, the Panel sees 6.98, i.e., about 7 KOhms, on the loop---which will probably, being a much higher resistance than 3.3K, be seen as an open (and I reiterate that I'm guessing here, and am not familiar with this Panel) and the zone will (probably) seem to "work" normally---at least most of the time. It "working" today doesn't mean that it will tomorrow---that is only predictable if you use the proper resistors for the zones as prescribed by the manual!
-------------------------------------------------------------



The reason I recommend putting EOLRs at the Control Panel, for home systems, is that it can make a lot of potential future problems easier to work with. The reason I specify home systems is that commercial and institutional systems need the EOLRs at the end of the line because of potential tampering from employees or customer-perps looking to circumvent the system.
In the first place, stores, warehouses, etc, tend to have a lot of exposed zone loop wires in public places and surface-mounted door/window sensors that can be tampered with in a few seconds of relative privacy. In the second place, they have a lot of casual traffic and you just can't watch everybody all the time. Installing resistors at the last sensor in a loop means you can't circumvent the loop by quickly twisting a pair of wires together, or clamping a short across sensor contracts.
Homes are a different story: With few exceptions, door/window sensors are recessed, not surface-mounted; and the wires connecting them are in walls, ceilings, unfinished basements, and attics; and not accessible to the general public or employees (unless you count household help, who are generally not a risk or they wouldn't be household help). You don't have a lot of customer traffic passing through your house--or if you do, then it's a commercial system, not a home system.
Now "easier to work with" can mean easier to troubleshoot if you ever have a problem with a zone. For example, if you have an "unexplained alarm" (aka a "false alarm"), one of the first things I check is resistance on the loop. Is it too high? (Should be only a few Ohms at most). Most importantly, is it steady, not fluctuating at all? But if the EOLR is at the end of the loop, a gold-band 3.3K resistor has a value of anywhere from 3135 to 3465 Ohms, a spread of 330 Ohms. The resistance is the loop itself is lost in that--you can't read it at the control panel. It's worse than trying to listen to music through heavy static.



Yes, it's true


The system when Armed will sound an alarm if there is an open on the loop, regardless of where the EOLR is. It's only with a short that supervision is limited or not, depending on how you install the resistor:
Yes, if a loop with an ATPR (At The Panel Resistor) is shorted in the attic--and only shorted--then the zone will stay "happy." But that's a circumstance that's vanishingly rare. Most alarm zone loops are carried in "quad" cable, 4 insulated wires enclosed in plastic sheath, a lot like household telephone wire.
The wires don't short spontaneously--the most common cause of a short is a staple shot thru the cable, or a drywall screw, or nail during the initial installation, which is found and fixed at testing; also during the installation.
The second most common cause is the quad or wire rubbing against something enough to wear through the wire insulation, nearly always metal water pipes or ducting. In that case, the wires can be shorted, but they are also grounded. Doesn't happen often, but it does happen. If you land (connect) the resistor in the panel on the gounded (low or negative) side of the loop, then grounding the loop creates a "ground fault" which will create a fault/trouble/alarm condition the same as an EOL short. (This assumes that the Panel is grounded, which it should be if it was installed properly.)
Squirrels, mice and rats can sometimes chew through wires in a attic, but that nearly always results in an Open, not a short.

I probably shouldn't even have mentioned where to place the resistors, but I've seen so many people set themselves up for a lot of grief they didn't need to endure. Most door/window sensors are 3/8" press-fit recessed contacts, many of which tend to wedge themselves into their holes so tight that you have to destroy them to get them back out, to work with contacts or splices, or change a resistor; and it makes changing out EOLRs a major chore. On top of that, the alarm industry is Balkanized in that every manufacturer uses different values for the EOLRs, for no good reason I've ever been able to figure out.
----------------------------------------------
One final recommendation: Re-post your questions on this specific alarm diy forum and get a second opinion from someone who has hands-on experience with your specific panel.
https://www.doityourself.com/forum/electronic-home-security-systems-alarms-devices-87/
 

ecm1949

Nov 22, 2021
8
Joined
Nov 22, 2021
Messages
8
Yes, I guess I will change the Lower Zones 3.3K to the 3.74K and the Upper Zones I will add the 6.98K. Just have to put them in the Control Panel since they are not being used except for Zones 9 and 10.
 
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