How do I disable a Zone that is showing an error?

[HAI_fjh]

IMHO even if the panel changes and the new panel needs 2.2K ohm resistors, for example. This is not a problem and you don't have to change the resistor in the contact to have it work properly with the new system and still retain the advantages of an EOL resistor.

There are a few articles on how to do this in our knowledge base (kb.homeauto.com).

Basic electricity 101: Resistors in parallel:

Let's say your previous panel required 2.2K ohm resistors and they are inside the contacts. You are replacing it with an Omni that requires a 1K ohm loop. What do you do? The easiest thing is to put a 1.9K ohm or 2K ohm resistor in parallel at the panel. Just put the resistor across the zone +/- terminals right at the panel. Very simple. When the zone (loop) is secure the resistance will be ~1K ohm. If the zone is shorted the resistance goes to 0 ohms and the alarm sounds. If the zone is cut then the resistance goes to 1.9K or 2K ohms and the Omni sees the zone as not ready and the alarm goes off.

The math:
2.2K ohms in parallel with 1.9k ohms = 1.02K ohms
2.2K ohms in parallel with 2k ohms = 1.045K ohms
both of these are close enough to 1K ohm +/_ 5% to work.

The basic rules:

If the existing resistor is less than 1K ohm add another resistor in series to bring the total resistance to 1K ohm.

If the existing resistor is more than 1K ohm add a resistor in parallel so that the total resistance is 1K ohm.

These are common problems that professional installers encounter every day and are easy to solve.

 

[Del91574]

HAI (Fred?) there's a few problems to doing what you're stating as being OK in the field....

Academically and mathmatically, it works, however in real life it does not work, and honestly negates the value of an EOLR and circuit supervision.

Installing a second (or however many) resistors in a series/parallel combination to make a spider so the panel "sets up" will work until....you fault the zone and most panels have a tolerance to the zone, and the better panels generate a trouble condition on a high resistance fault, which is what is going to happen with a resistor combination with one in series another in parallel, unless your panel specifically supports a DEOLR combination, and hoping that the resistor values are close enough or the same to work with such a combination.

So, citing your example, a 2.2K EOLR zone, with resistors buried in the field, being swapped to a 1K EOLR panel, with a second resistor being added in parallel to make a 1K EOLR zone...faulting the zone will result in a 2.2K EOLR zone as far as the panel is concerned, even if the protective circuit is open, which is a high resistance short....not an open or closed or EOLR. If the panel doesn't react to a high resistance short (while disarmed) as a trouble condition, that would be a design flaw within the panel IMHO. Most panels I know of with 2K or 2.2K have a loop tolerance of 300-400 ohms above EOLR value before generating a trouble (while disarmed).

It's almost as bad as taking an EOLR zone and then dividing the resistance up by X or Y and installing a resistor at each device. May work with some of the poorer designed panels, but put a panel that really supervises and provides trouble conditions on the zone, you'll see what really happens. We had a couple of companies around here that used to take a 2.2K panel and break it up into 4 devices with 560 ohm resistors. Try explaining to someone why their panel failed to detect X or Y.

While I'm not a fan of it, if EOLR's are buried in the field and inaccessable, I have used them to trigger the coil on low trigger draw relays to fault the zone itself, an old trick from the days with swinging zones (foil, etc.)

 

[Mr Spock]

All good points.

Using series and parallel resistors is basic electronics.

Resistors in parallel = (R1*R2) / (R1+R2)

Resistors in series = R1+R2

So can anyone tell me what the HAI panel's tolerance on EOL resistance sensing is?