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4.22.20 – SSI –

Tech expert Bob Dolph shares some alternative sources for many of the Sentrol sensors that will no longer be available, as well as application resources

I would like to start out this month’s column with a brief memorial prayer. This is in remembrance of a great old-time sensor manufacturer, Sentrol. So, here’s to you Sentrol! May you rest in peace. We will all miss you.

I can recall back in the 1970s, Sentrol was a sensor leader and then it was acquired, and acquired, and acquired, etc. Eventually it was under the roof of United Technologies Corp. (UTC) as part of Interlogix, and we all know how that ended.

Shame on you United Technologies for just dropping such an iconic company into the financial sewer. The loss of Sentrol often reminds me of the song, “Where Have All the Flowers Gone?”

Ok, wipe your tears, as we must move on. In keeping with this year’s theme of different ways professional security dealers can keep themselves separated from all the DIY and amateur riff-raff emerging today — having an arsenal of specialized alarm sensors and knowing how to apply them is a good start to proving you are the pro.

To start out I want to point to you a still FREE fabulous alarm sensor application notebook. It is the “Intrusion Sensor Application Notebook” and is buried in the Interlogix Online Library.

Even though the products will no longer be available, this is still a great 192-page reference book with many sensor application examples and explanations. Download while you still can. I am not sure how much longer this resource will be available. Now let’s look at some sensors.

Magnetic door and window alarm contact sensors are probably the most common and widely used in the industry. They are also one of the most misused and misunderstood. They are typically comprised of one part magnet and one part sensitive magnetic reed switch that is hermetically sealed in a protective glass enclosure.

How many times have you needed that extra little tap to press a recess contact into a slightly undersized hole? How many times have you done this with the heel of your screwdriver?  That is a big no-no, as the slightest extra compression can fracture that glass-sealed reed enclosure.

Air may then infiltrate the broken protective environment. You may not have performance issues immediately, but down the road this environmental intrusion can often cause intermittent performance of the alarm contact.

Respect the delicate nature of these devices. You should only use slight finger pressure to seat that recessed alarm contact. Anything more and you should make the hole slightly larger.

Here’s a tip: If you need to drill a larger hole and the wire is already pulled through the hole, you may want to consider this month’s Tool of the Month.

Speaking of GRI, I will let you in on a little secret. GRI has a wonderful substitute listing of its sensors for other manufacturers, including Sentrol.

Another new kid on the block that you may have not looked at yet is Magnasphere. This company too has a comparison listing for previous Sentrol door contacts. Magnasphere offers a unique alternative to the traditional reed switch, which in turn offers high resistance to breakage, magnetic tampering and contact welding. That is a quality selling point.

Another old Sentrol favorite was the 5402 / 5422 shock sensors. They were self-powered and UL Listed. This is a good example of the uniqueness of certain Sentrol products. Some similar shock sensors are Honeywell’s SC100 Series seismic vibration sensors or the GRI Shockgard 1 SG-1.

Sentrol was also known for its extensive glassbreak sensor line known as the ShatterPro Series. In particular, the 5820 Recessed ShatterPro II was very low-profile. One possible alternative to this is the Honeywell FG1625RFM glassbreak detector.

In addition to the previously mentioned brands, other potential alternatives to popular Sentrol sensors can be found from United Security ProductsAmseco/PotterFlair ElectronicsSeco-Alarm and Tane Alarm. I think you will find these as good resources for alarm sensor alternatives. My apologies to anyone I might have missed in this listing.

Tool of the Month

It not uncommon to have a door or window alarm contact cable pulled only to find out the predrilled hole is undersized. Pushing the cable back in the wall to redrill is a pain.

This is why I have selected the specialized ReBore-Zit tool from Labor Saving Devices as the Tool of the Month. It allows you to redrill a hole with the sensor cable intact. Magic? Maybe.

About the Author


Bob is currently a Security Sales & Integration “Tech Talk” columnist and a contributing technical writer. Bob installed his first DIY home intercom system at the age of 13, and formally started his technology career as a Navy communication electronics technician during the Vietnam War. He then attended the Milwaukee School of Engineering and went on to complete a Security Management program at Milwaukee Area Technical College. Since 1976, Bob has served in a variety of technical, training and project management positions with organizations such ADT, Rollins, National Guardian, Lockheed Martin, American Alarm Supply, Sonitrol and Ingersoll Rand. Early in his career, Bob started and operated his own alarm dealership. He has also served as treasurer of the Wisconsin Burglar and Fire Alarm Association and on Security Industry Association (SIA) standards committees. Bob also provides media and training consulting to the security industry.