Why Does My Burglary Zone Say It's Open When It's Closed?

Burglary zones show a fault when the circuit is no longer in a normal state. This is true of both wired and wireless burglary zones. When it comes to wired burglary zones, magnet alignment is important but there are other factors to consider. The wiring and the resistor are also key elements.


Wireless Sensors

Wireless door and window contacts must have the magnet properly aligned with the sensor. Improper alignment and/or magnet spacing will cause a fault to display for the zone even when the door or window is closed. Check the installation guide for the contact to verify proper magnet spacing. Wireless contacts also usually have marks on the sensor to show which side the magnet should be placed on, and how to properly align it.

Most wireless sensors also have a cover tamper. If the cover is not properly seated or is misaligned, this can cause a tamper trouble to show for the zone. In some cases, a tamper signal that has been acknowledged by the user pressing any button on the keypad, or by entering a disarm command, will then change to a display of fault and will remain until the tamper condition has been corrected. Do this by properly seating the cover on the wireless sensor. In some cases, another disarm command will be required to completely clear the trouble/fault display.

If this is a new system setup, and the sensor faults upon first opening but then does not restore once the door or window had been closed, you should ensure that you are using the correct loop number for the wireless sensor. This is particularly true for Honeywell and 2GIG wireless sensors. In this post, we list many of the Honeywell wireless loop numbers for commonly used sensors. When the wrong loop number is programmed, the panel will receive the initial fault signal, showing that the door or window was opened, but from that point forward, it will never successfully receive any opening or closing signals from the sensor, which is why it gets stuck in the faulted state. This is why proper loop number programming is important. Please be sure to check your sensor's documentation for proper programming and loop assignment.

Magnet Issues

When dealing with hardwired sensors, the contact and the magnet may also become misaligned. Door and window sensors always include two (2) parts. The part that is connected to the wiring is the actual sensor. This is the part of the contact that will mount to the door or window frame, the unmoving portion of the opening. The sensor usually contains a reed switch. The other portion of the contact is the magnet, and it is mounted to the moving portion of the opening. These two devices must properly align with each other when the door or window is closed.

When properly aligned, the magnet causes the reed switch to close, which closes the circuit, and puts the zone in a normal state (as long as everything else is configured properly). When installed on a door or window it is usually not possible for the magnet and sensor to be touching each other. This is where the magnet spacing gap comes into play. You always want to install the contact with the least amount of gap possible between the sensor and its magnet, but the gap rating is the maximum allowed space between the sensor and the magnet while in the normal state. If the magnet exceeds this gap while in the closed state then the zone will indicate that it is open, even though the door or window is actually closed. Most sensors have a gap rating of around one inch, though there are specialty contacts with a wide gap rating. This document shows many of the Honeywell wired door/window contacts and their gap ratings.

Wiring Issues

Faults on hardwired zones can cause a lot of grief, whether you're trying to arm the system or just trying to get your keypad to show that it's ready to arm. Let's begin by taking a look at the wiring for a burglary zone. Most burglary zones are Normally Closed contacts. These include door/window contacts, motion detecting sensors, and glass break detectors.

When using a hardwired, Normally Closed contact, we suggest that you always use an EOL (end of line) Resistor whenever possible. The control panel or hardwired expander being used will determine the size of the resistor. Some alarm panels and/or expanders may not require EOL Resistors on all zones or may make them optional. If you choose not to use an EOLR, you must verify that the device you are using allows that. We also suggest trying to only have one (1) contact per zone. In the illustration below, with two (2) Normally Closed contacts in a closed state, the circuit's resistance should be very close to the value of the resistor.

The panel or expander you are using will have a tolerance associated with the resistor value. This tolerance is necessary because the wiring and the sensors used for the zone will all have a minor amount of their own resistance, which must also be accounted for. The amount of tolerance is specified by the manufacturer of the panel or the expansion module you are using. Zone tolerances are typically from 100-300 Ohms. Please check the documentation for the device you are using to determine the proper values.

The wiring could have failed. Alarm wire varies in how many wires, also known as conductors, are contained inside the outer sheath. Wire thickness, wire consistency, length, and whether shielded or unshielded, are also variables. In alarm systems, you will often see 4-wire or 2-wire cabling. This indicates that the wire is either 4 conductor, or it has 4 wires inside the outer sheath, or 2 conductor, with 2 wires inside. The thickness of the inside wires is measured using the term, gauge. We recommend 18-gauge or 18 AWG (American Wire Gauge) for the widest application support, and sometimes 22 AWG, which is acceptable in many applications. The higher the gauge number the thinner the wire is, which translates into shorter acceptable wire runs.

Wire consistency for alarm systems is either solid, (1 solid wire) or stranded (a number of smaller strands wrapped together to form a single conductor.) Solid wire does not bend as easily as stranded wire and can break with repeated bending. For this reason, we strongly recommend using stranded wire for all installations. Alarm wire can be shielded or unshielded. Shielded wire contains an extra component used to limit interference. This is a metal mesh layer between the outer sheath and the inner wire conductors. While this sounds like a good idea, shielded wire is usually not preferred in alarm applications. It can, at times, introduce issues and in nearly all instances will reduce the total acceptable distance you can run an individual wire.

While a voltmeter is an excellent way to measure the resistance or continuity of wire, thereby allowing you to determine if there's a break somewhere in the circuit, wire that is already installed is usually terminated in two different areas, making it impossible for the multimeter leads to reach both ends. This is where a cable tone & probe set would be a better option. This tool will allow you to determine if there is a break in a wire run, and if so, where the break is.

Resistor Issues

The resistor could have failed. Resistors have a value that is signified by their color bands. There are many online resources that explain how to tell the value and the tolerance of a resistor. The resistor tolerance is the amount the resistor may vary from its stated value. If you check a resistor with a multimeter and it has a reading outside of its stated value ± its tolerance, then the resistor is bad. Most of the resistors used in alarm systems come in either 4-band or 5-band values. You can see an example of a 5-band resistor in the image below, this resistor has a value of 5.2k Ohms with a 1% tolerance.

Resistors are typically rugged and will last a long time, but as with most things, they too can fail. When they do fail, usually you cannot tell visually. You must measure the resistor with a multimeter to determine if it is still reading the proper value, within tolerance. A multimeter gets the name "multi" because it can measure AC and DC voltage, current, and resistance among other things. If this is a newly setup zone and it is showing open when it should show closed, please verify you have wired the resistor correctly. For Normally Closed contacts the resistor should be wired in series. For Normally Open contacts, the resistor should be wired in parallel. If it is wired incorrectly, the burglary zone may behave backward, where it shows faulted when the sensor is closed and closed when it is actually open.

Panel Programming

For a hardwired zone to operate correctly, it also requires the zone to be properly programmed. Depending on the device you are connected to, you may or may not need an EOL Resistor. Although we recommend using one when possible, if the device allows, you may have an option to wire it as Normally Open (NO) or Normally Closed (NC) without using a resistor. Whichever option you choose, you must ensure the programming of the zone matches how it is wired. Some programming options include NO, NC, EOL, Zone-Doubled (ZD), or even Double-Balanced (DB). Double-balanced logic is an in-depth zone configuration that provides additional tamper protection. It is for high-security installs and is rarely used. It is important that your programming option matches how the zone is wired.

Bad Device Zone

At times a zone not operating correctly can be traced back to the zone itself. Whether this is a panel zone, zone expander, or some other type of device, it can go bad. It is not common but it happens. The easiest way to determine if the zone itself has gone bad is to swap the wiring of a similarly configured, but properly working zone to the terminals of the zone you're having issues with. If the problem remains with the zone number, it is likely the zone input itself is bad.


All of the above issues will cause a zone to display a fault in error. On a wired burglary zone with an EOLR, a fault can indicate either a short or an open circuit. An easy way to determine if the zone has a short or an open is to meter the zone terminals for voltage. If the zone measures 0 Volts DC, the zone is shorted. If the zone has voltage, then you know it's not a short. If you're not sure what this voltage indicates, find another zone on the panel that is working properly and has the same characteristics as the problem zone. Meter that zone for voltage while the zone is open but with the resistor in place. You can then compare this to your problem zone's voltage. If the problem zone has a higher voltage than the properly working zone, this tells you that it is open, and the resistor is not being seen. This can tell you what the problem is, but not necessarily where it is.

To figure that out, you can measure the resistance of the circuit. To do this we recommend that you first power down the panel or expansion module. To do this, you must unplug the battery and the transformer to the panel, or disconnect the power wires from the expander. Then remove the zone wiring that you're troubleshooting and use a voltmeter, capable of reading resistance. Do this by placing one meter lead on one of the zone wires you removed from the terminals on the panel or module, then put the opposite lead on the other wire you removed. Try to keep your fingers from being metered, as you also have a certain amount of resistance that the meter will pick up. You'll need to know what the expected resistance is for the panel or module.

Before you wade into troubleshooting wiring and resistors, always remember to check the sensor magnet first. This is both the easiest and the most common issue. Make sure the magnet is still in place and that it is at an acceptable distance (gap) from the sensor based on the manufacturer's specifications for it. Moving the magnet closer to the sensor could solve the issue. If not, then move into troubleshooting the circuit using the information above. Troubleshooting an existing zone that has been working and then suddenly has issues is different from troubleshooting a newly installed zone. With a zone that was previously working, you can usually assume that the programming is correct and that the correct resistor value and placement were used initially. A wiring issue, a resistor issue, or a magnet placement issue could still have occurred recently. Particularly with magnets that are installed using only double-sided foam tape.

Some zones may have multiple devices on a single circuit. This does make troubleshooting more difficult since we do not know which contact on the circuit may actually be causing an issue. It could be any of the multiple sensors in the circuit or none of them. While the above troubleshooting steps still apply in this situation, it takes the complexity of troubleshooting up to another level.

The biggest issue with troubleshooting a fault condition that shouldn't exist usually arises when some of the wiring is not accessible. In some installations, you will only have access to the wiring at the zone terminals themselves. In this case, again, you want to completely rule out the magnets of all sensors first. Alarm sensor magnets are usually just strong magnets. There is nothing special about them, aside from the fact that they are made to be similar in appearance to the corresponding sensor. If you have a strong magnet around the house, like a rare earth magnet, test it with a normally working sensor on a different zone to see if it's strong enough. Some larger, thicker refrigerator magnets may suffice. If the magnet works when placed next to a known working contact, you can use it to test the sensor(s) that are showing an erroneous fault. Alternatively, you can purchase spare or replacement alarm sensor magnets to rule out a bad magnet being the issue.

After that, you would move into measuring the resistance of each component that you can access. If you are unable to track down the issue because of an inability to access the wiring, you could see if you are able to run a new wire. If rewiring is not an option, and you've reached the end of troubleshooting every component that you have access to, then at this time we recommend converting all affected sensors over to wireless sensors if this is an option.

If you don't have access to the necessary test equipment there are still things you can do to troubleshoot this type of issue. With a zone programmed for EOLR, you can "strap" the zone out. "Strap" is just a term for putting the resistor across the two (2) zone terminals while eliminating any wiring from the zone. Once strapped, you can manually simulate a door opening by removing one leg of the resistor, this should cause a fault. You can short across the resistor with a screwdriver or a short piece of wire, and this should cause a fault as well. This ensures the zone, the programming, and the resistor are all correct.

After performing the test from the paragraph above, you can then check to see if one or more contacts are causing an issue. If your contact has terminals at the sensor, (like the one pictured below) starting with the contact closest to the panel, you can remove the wiring from the contact and connect the two (2) wires together to simulate a closed contact. If the zone is programmed to look for an EOLR, be sure you have one in the circuit. If the zone fault clears, this tells you that the wiring up to the first contact is good. Connect the wires back to the contact, but if there are other contacts in the same circuit after this one, don't reconnect them at this time. With the single contact wired into the circuit, does it show open and closed status properly? If so, then this contact is good. You must now perform a similar test on each contact in the circuit until you figure out where the problem is. You can perform this same type of troubleshooting if your contacts have wire jumpers permanently attached, but it may be slightly more difficult.

If you have hit a brick wall and you are an Alarm Grid monitored customer, you can email us at support@alarmgrid.com. Alarm Grid monitored customers receive free remote technical support. Remember that our support hours are Monday - Friday from 9:00 am - 8:00 pm Eastern Time, excluding holidays. If you contact us outside of our regular hours, we'll get back to you as quickly as possible on the next business day.

Did you find this answer useful?

We offer alarm monitoring as low as $10 / month

Click Here to Learn More

Answered By