Who Has Door Position Switch Recommendations?

A class member in our Access Fundamentals class asked recommendations on door position switches/ contacts you have good success with. (See Door Position Switches Tutorial for the basics.)

As an integrator, I typically used generic magnetic contacts and Dynalock roller ball plungers. Some of you may have strong preferences for specific types based on field experience.

So can you help? Do you have a certain brand or model that is your 'go-to' sensor?


I have never installed a DPS.

Have allways used the built in status in either maglock's or strike's. Much better way to see that a door is shut and locked. Maglocks offer "bond" or "sense" status that tells you that the magnet is engaged. Strikes offer latch bolt monitoring and latch bolt strike or keeper status which when used in series give you positive shut and locked (secure) feedback.

Have allways used the built in status in either maglock's or strike's.

While I think it's very smart to use latchbolt monitors/bond sensors to confirm whether a door is locked, there can be problems using them as position switches, namely they don't monitor door position, just by correlation 'lock status'.

They are useful as a supplementary input for sure. Having positive confirmation a door is closed and also locked is useful. But by design, the lock status only confirms if a lock is active/engaged, not the position of a door.

What happens when a user scans a badge, unlocks a lock, but is unable to enter? What if someone tampers with the latch bolt monitor? What if maglock power drops? Logical problems can be mitigated by using both sensors together.

You make a good case for not relying solely on the door strike sensor, but can you give some more examples on why a maglock bond sensor is generally insufficient for determining door status?

My naive thinking is that in the case when the power drops to the maglock, although the door may be technically 'closed', it is not secure, so it should be reported. The bond sensor would be NC when working, and naturally fault to 'open' in case of power loss.

Some municipalities forbid maglocks outright, so there's always that.

In many cases, a power drop (or fire alarm) kills a maglock dead by code, but there is no requirement to kill a door controller. Being able to confirm a door remains shut during one of these events is valuable. (Backup power to controllers/PoE switches are common.)

The door many be unlocked, but the door position switch monitors if the door is actually ever opened. For some facilities, this could be huge.

We have used the GRI 18412's for our recessed door contacts, and they also make a good surface mount option. They aren't terribly expensive either.

GRI Door Contacts

In new installs where we were doing access AND intrusion, I used to use the GRI AA/AC dual contacts, so we didn't have to install two separte ones. Otherwise I used their standard recessed and surface mounts.

They seemed to be more reliable, rust and fail less often, and had rare earth magnets for wide gaps. They also had the handy plastic mounting legs for steel doors with a top channel, which I don't recall being too common among manufacturers.

I tried to change out to other manufacturers occasionally, but techs always preferred GRI and complained about others.

Sentrol used to be the dominant market leader in magnetic contact switches. I have probably specified tens of thousands of Sentrol switches over the years. They were then bought by GE Security and went downhill fast, and then spun off to Interlogix. They still make a good product, but the number of product options available is only a fraction of what Sentrol originally had.

GRI is now my preferred manufacturer of magnetic contact switches. Honeywell Security also offers some good options.

It is my opinion that bonding sensors in mag locks and latch bolt monitors in electric strikes should be used in conjunction with, not in place of, door position switches. They provide different functions and you can get some interesting results when you try and substitute one for the other.

For example, many access control systems reset the door unlock time when a door is opened. This is to prevent a second person from passing through the door after the first person walks through. If you use a bonding sensor on a mag lock as your door switch input, the door has the potential to immediately relock itself after a card has been presented.

We've had issues with maglocks with built in DSM (door status monitoring), though not through any fault of the maglock. Our technicians have had a hard time lining up the maglock properly and as a result we have seen several doors with intermittant false "door held" or "door forced" alarms. The RCI mini-mags that we have used most often are not very forgiving in lining up the DSM contact.

Thanks to everyone who has replied. Your information is helpful. I am specifically looking for a good "monitored" electric strike lock for use in exterior doors. Our standard is to use door prop alarms. When the sensing devise built into the electric strike is not consistently accurate, we get door prorp alarms on doors that are actually adaquately locked. We welcome the alarms when the door is not secure, but alarms on secured doors is a real problem.

We have always opted for optical sensors as opposed ot the mechanical plunger type. We fear dirt and the elements will impact the movment of the plundger. If anyone is aware of a good/reliable monitored electric strike, I would love to hear about it.

THANKS!

We have had good luck with the HES 5200 series strikes. Specifically the ones with "Latchbolt Monitoring" (LBM) and "Latchbolt Strike Monitoring" (LBSM). Wired like the sample schematic below gives you shut and locked status.

99% of the false alarms we get are because the door is installed badly not due to switch failure. Also using the wrong lockset is going to give you headaches.