Nuisance door held and forced alarms

Likely causes

• Door position switch gap past the switch's make and break distance

  ~25%

  Hold the door tight closed and the alarm clears; let it rest against the stop and it trips. Measure the resting magnet-to-switch gap and compare it to that switch's published make and break: recessed and wide-gap types differ a lot, and it is always a published per-model number.

• Request-to-exit not shunting the door position switch

  ~20%

  Forced alarms correlate with people leaving and never with people entering. Press the REX and watch whether the panel logs a shunt at all: no shunt event means the input isn't wired or isn't programmed to shunt.

• Latch not re-latching on close

  ~15%

  Push the closed door gently and it pops without touching the lever. The position switch says closed; the latch never threw. Look for latch or bolt monitor events if the hardware has them.

• Held-open timer shorter than real human use of the door

  ~12%

  Alarms cluster at shift change and delivery windows and clear themselves. Look at who uses the door: carts, deliveries and accessible users all need longer than a very short timer allows.

• Door closer out of adjustment, failed, or obstructed

  ~10%

  Release the door and it stops short or drifts instead of latching. Accessible doors want a slow enough sweep, at least 5 s from 90 to 12 degrees, so a fast held timer plus a compliant closer is a guaranteed alarm.

• Relock and shunt timing out of order against the strike time

  ~8%

  Log shows granted, then open, then forced within a second or two of the strike time expiring. The shunt window and the strike time aren't lined up with how long the door is actually open.

• Position switch failing, wired to the wrong input, or the wrong end-of-line value

  ~10%

  Simulate each state at the panel terminal with resistors and watch whether the panel's door state follows. If it doesn't, the door is innocent: it's the input, the programming, or the supervision value. EOL values and the expected resistance for each state are panel-specific; 1k, 2.2k and 4.7k are all common, so look up the panel's own table.

What to bring

• Laptop or phone with live event log
• Feeler gauge and shims
• Tape measure
• DMM
• Resistors to the panel's specified EOL values
• Closer adjustment tools
• Ladder

Steps

1. 1

   Step 1: Stand at the door with the live event log open and cycle it

   Badge in, exit, then let it close on its own while you watch open, closed, granted, forced and held in real time. Which event fires, and in what order, names the fault. Free, and it beats an hour of guessing at the head end.

   If that doesn’t do it

   Measure the switch gap.

2. 2

   Step 2: Measure the door position switch gap at rest

   At the closed, resting position, magnet to switch, against that switch's published make and break. Marginal gaps are the single biggest source of phantom door alarms. Shim or move the magnet; do not extend the timer.

   If that doesn’t do it

   Prove the input at the panel.

3. 3

   Step 3: Prove the input at the panel, the right way for the input type you have

   On an unsupervised two-state input, a hard short and a hard open are valid and must flip the door state. On a supervised input they are NOT: short and open are both trouble states, and the two door states are two specific resistance values. Look up the panel's expected value per state and simulate each one with resistors, then short and open deliberately to prove trouble reports as trouble.

   If that doesn’t do it

   Panel state doesn't follow the simulated values: stop working on the door. It's the input, the programming, or the EOL value.

4. 4

   Step 4: Verify the REX actually shunts

   Press it and confirm the log shows the shunt and no forced alarm. Make sure the shunt window covers the time a real person takes to get through, not the time you take. A REX that shunts is not the same job as a REX that releases. See Door won't release for egress.

   If that doesn’t do it

   Watch the latch throw.

5. 5

   Step 5: Watch the door close, latch and report secure unassisted

   Release from 30 degrees as the quick latching check, no hand on it. If the door is fire rated, that is not the test that counts: a fire door assembly must close and latch from the fully open position, and that is what gets checked at the annual inspection. A door that latches from 30 and stalls from 90 will pass your quick check and fail in a fire.

   If that doesn’t do it

   Adjust the closer and the strike, then re-test, from full open on a rated door.

6. 6

   Step 6: Tune the timers last, and only last

   Strike time is typically 3 to 7 s and held-open typically 15 to 30 s. If the only way to stop the alarms is a very long held timer, you've buried a closer or alignment fault and the customer will call again, probably on your day off.

   If that doesn’t do it

   Write up the door hardware for the locksmith or the GC.

More Access Control guides

• Reader dead: no light, no beep
• Valid read, door never unlocks
• Denied at certain times or certain doors
• Card works at one door, not another
• Intermittent reads and ghost reads on Wiegand
• Read range short at one reader
• Keypad won't take the PIN

All 54 guides