Selecting the Right Electric Strike

By: Brian Rhodes, Published on Jan 22, 2013

Despite being one of the most common components of access control, specifying the right electric strike can be deceptively complex. Understanding the particulars of each device can be overwhelming. In this note we describe which characteristics of strikes are most important and how to select the right one.

Function Explained

Strikes are basically moveable portions of the door frame, consisting of 3 main components, shown to the left:

  • The Strike Box contains the internal components to the strike that sits inside the frame. Electric strikes are typically driven by one or more solenoids, either directly or via a simple geared carriage inside the box.
  • The Strike Plate affixes the device mechanism to the frame and is responsible for the proper alignment the device in relation to the door locking hardware.
  • The Keeper is the component of the strike that moves. When 'locked', the keeper is rigid and forms a positive stop - interfering with the latch to prevent opening of the door. When 'unlocked', the keeper swings out of the way of the latch and allows the door to open.

Unlike other types of hardware, strikes do not replace or improve the existing hardware mounted on a door. In fact, a strike totally relies on mechanical door locks for securing the door. The strike simply allows for the locking hardware to remain locked and still gain entry through the opening.

Fail Safe/Fail Secure: Unlike maglocks that 'fail safe' on power loss, strikes can be configured to 'fail secure' - meaning the keeper remains rigid regardless if they are powered or not. In order to preserve the life/safety compliance of the opening, the door hardware must accommodate free egress in an emergency. Whether through panic bars/exit devices, lever sets, or even latch sets, egress doors cannot be locked to prevent escape, and hardware must take no more than one, intuitive action to open the door.

AC or DC powered: Most modern strikes either allow selecting between AC and DC or available in AC or DC versions. All strikes are low-voltage, with either 12 or 24 volts standard. Final polarity and voltage selection depend on several design criteria:

        • Noisy vs. Quiet: Due to differences in the way solenoids handle power types, AC electric strikes make a characteristic 'buzzing' noise when operating, while a DC model is quieter (or even 'silent'). In the past, solenoid reliability was tied to polarity types, but modern strikes can be purchased to exceed 'Grade 1' reliability, leaving polarity choices subject to matching existing power supplies or tolerated noise.
        • Battery Backup vs. Low Current Draw: Since 12 VDC 'backup' batteries are common to many electronic systems, they are an inexpensive option for backup power compared to 24 volt cells. However, the current draw of 24 volt strikes is typically lower than 12 volt versions, so if multiple devices are to be powered from a single source or if overall energy consumption is a concern, 24 VDC devices are a popular choice.

Integrated Readers: A newer trend in strike design is integrating a proximity-style reader into the device and running both power and communication bus down a single cable. This integration allows a more streamlined installation and offers a less intrusive install by combining the reader and strike into a single unit. Variants exist that include 'read-in' and 'read-out' capability, with the unsecured side reader being connected through the frame or wall assembly via bluetooth.

Door/Latch Monitoring: A common option for many strikes is a latch monitor, or a simple contact switch that detects when a latch bolt is being contained inside the strike. This sensor also functions as a defacto 'door position' contact, since the door must be shut for the latch to be present. While not all strikes feature this switch, it usually does not add significant cost to the device but greatly enhances the reporting function of the device.

Strike Types

Get Notified of Video Surveillance Breaking News
Get Notified of Video Surveillance Breaking News

Selecting the right type of strike includes considering the 'form factor' of the device. Strike are available in two common types:

Mortise: The most common type of strike is the mortise variety, which typically requires a cutout in the frame for install. Mortise Strikes are used when the door locking hardware is a mortise or cylindrical lock - or any other lock whose latch is retracted into the door leaf during operation. Since the bolt protrudes into the frame, a mortise strike's keeper replaces a portion of the reveal. As we will cover in the installation section, installing a mortise strike requires the strike to be installed deep into the frame, often requiring frame material to be precisely cut away for a clean fit.

Surface: These types of strikes are used when the companion locking hardware is a 'rim style' device, meaning it is mounted to the inside surface of the door [link no longer available] rather than inside the door. Common 'rim' devices are 'exit devices [link no longer available]' or surface deadbolts. Even though a portion of the device protrudes on the 'door rabbet', the strike box may still require an additional cutout in the frame for proper mounting.

Strikes Vs. Other Hardware

The relative value of strikes compared against other electrified hardware types

Pros

  • Inexpensive: Strikes are among the least costly electrified devices, with Grade 1 quality devices selling between $100 - $300. Compared to locks like maglocks that range between $400 - $ 1000 per unit. Even when considering the installation labor, the cost of a strike is between $175 and $375 per door.
  • Reuses Existing Hardware: Another benefit of strikes are they are specified to work with door hardware already in use. Not only does this reduce the 'hard cost' of buying more locks, it saves on the 'soft costs' attributed to re-keying, installation labor, and redistribution of mechanical keys.
  • Energy Efficient: Unlike maglocks that require a steady impulse of electricity to operate, a strike uses only intermittent impulses to operate. While the operational amperage is relatively small for either device, when multiplied over tens or even hundreds of doors, using strikes can cut hundreds of amps from a facility's electricity consumption.

Cons

  • Wear: Unlike maglocks, strikes cannot be installed once and operate for years without attention.Since electric strikes have moving parts, they can wear or break over time. Components like load springs and solenoids require periodic maintenance attention.
  • Adjustment is Vital: Since the strike is totally dependent on the door's locking hardware for security, the relationship between strike and latch is vital and the tolerances for movement are limited. Even during the course of normal operation, door hinges sag, door frames shift, and door latches fall out of throw range of the strike. Anywhere strikes are used, a companion door maintenance problem is vital to guarantee security.
  • Extra Hardware: In some cases, additional hardware is required to protect the strike. Take the example below, where an exposed exterior strike is vulnerable to outside tampering unless additional 'latch protectors' are installed on the door:

Installer Skill Required

Properly mounting a strike takes considerable skill in precision measurement and often requires cutting metal. While the overall installation process is typically straightforward, the installer's craftsmanship and trade skills determines more than cosmetic quality - the operation of the device is affected as well.

For example, while frame cuts are simplified by the use of mounting templates included with the device, the position of the template is subject to accurate measurements and assumptions that the frames, doors, and existing hardware are square and properly mounted.

Successfully mounting a strike free of problems like "preloading [link no longer available]" (often caused by misalignment and warping of the door) requires the installer to apply a skillful eye to the door condition before beginning work, and be prepared to correct structural problems by shimming hinges or even replace a warped door leaf. Will will examine the problems, and their corrective actions in an upcoming report on "Maintaining Electrified Hardware".

6 reports cite this report:

Fail Safe vs. Fail Secure Tutorial on Oct 02, 2019
Few terms carry greater importance in access control than 'fail safe' and 'fail secure'. Access control professionals must know how these...
Access Control Lock Guide on Sep 26, 2018
In this guide, we examine locks; critical elements of any security system and fundamental parts of every access control system. Two fundamental...
Assa's Lowest Power Draw Maglock: Securitron M680E Examined on Feb 14, 2018
Securitron produces some of the most extreme maglocks on the market, including massively strong maglocks and even ones with integrated CCTV cams...
Top Maglock Provider Warns Against Using Maglocks on Nov 21, 2017
Do not buy my company's product. It sounds strange indeed, but a senior Allegion consultant stated that maglocks should not be used in common...
Most Needed Improvement: Access Control Software on Feb 16, 2015
100 integrators answered IPVM's question: "Which aspect/element of access control system technology (ie: credentials, locks, controllers,...
Electric Strikes: Why They Are So Popular on Jul 31, 2014
Electric strikes are a mainstay part of access control, but how often do integrators use them? In our recent integrator insights survey, we asked...
Comments : PRO Members only. Login. or Join.

Related Reports

Access Control Door Controllers Guide on Oct 22, 2019
Door controllers are at the center of physical access control systems connecting software, readers, and locks. Despite being buried inside...
Securing Access Control Installations Tutorial on Oct 17, 2019
The physical security of access control components is critical to ensuring that a facility is truly secure. Otherwise, the entire system can be...
Access Control Course Fall 2019 - Last Chance on Oct 17, 2019
Register Now - Fall 2019 Access Control Course. Thursday, October 17th is the last day to register. IPVM offers the most comprehensive access...
Altronix Claims Tango 'Eliminates Electricians' on Oct 15, 2019
Power supply provider Altronix claims its new Tango power supply 'eliminates the need for an electrician, dedicated conduit and wire runs'. In...
Pelco CEO Out, New CEO Found on Oct 15, 2019
Just 2 months after Pelco was sold, Pelco's CEO is out, with Pelco bringing in an outside President and searching for a new CEO from the industry,...
Camera Focusing Tutorial on Oct 14, 2019
Camera focus is fundamental to quality imaging. Mistakes can significantly reduce details, making cameras less effective. In this guide, we...
Last Chance - Register Now - October 2019 IP Networking Course on Oct 10, 2019
Last Chance - Register Now - Fall 2019 IP Networking Course. The course starts next week. This is the only networking course designed...
HID Fingerprint Reader Tested on Oct 09, 2019
HID has released their first access reader to use Lumidigm optical sensors, that touts it 'works with anyone, anytime, anywhere'. We bought and...
Avigilon H5A Analytic Cameras Tested on Oct 07, 2019
Avigilon has released its H5A analytic cameras, claiming to "detect more objects with greater accuracy even in crowded scenes." We tested the...
'Bunker Busting' Wireless Access Startup: Sure-Fi Profile on Oct 03, 2019
An access startup is claiming its 'bunker busting' wireless Wiegand radios can punch through 'any obstruction'. We examine their offering,...

Most Recent Industry Reports

Access Control Door Controllers Guide on Oct 22, 2019
Door controllers are at the center of physical access control systems connecting software, readers, and locks. Despite being buried inside...
Alarm.com Acquires OpenEye on Oct 21, 2019
Alarm.com is targeting commercial expansion and now they have a commercial cloud VMS with the acquisition of OpenEye. In this note, based on...
Government-Owned Hikvision Wants To Keep Politics Out Of Security on Oct 21, 2019
'Politics' made Hikvision the goliath it is today. It was PRC China 'politics' that created Hikvision, funded it, and blocked its foreign...
Integrated IR Camera Usage Statistics 2019 on Oct 21, 2019
Virtually every IP camera now comes with integrated IR but how many actually make use of IR or choose 'super' low light cameras without IR? In...
Alarm Veteran "Demands A Criminal Investigation" Of UL on Oct 18, 2019
The Interceptor's Project pressure against UL continues to rise. Following Keith Jentoft's allegation that "UL Has Blood On Their Hands", Jentoft...
Camect "Worlds Smartest Camera Hub" Tested on Oct 18, 2019
Camect is a Silicon Valley startup that claims the "Smartest AI Object Detection On The Market", detecting not only people and vehicles, but...
Hikvision Global News Reports Directory on Oct 17, 2019
Hikvision has received the most global news reporting of any video surveillance company, ever, ranging from the WSJ, the Financial Times, Reuters,...
Camera Calculator V3.1 Release Improves User Experience on Oct 17, 2019
IPVM has released a new version of our Camera Calculator, V3.1, with significant user experience improvements, a new development plan, and an...
Securing Access Control Installations Tutorial on Oct 17, 2019
The physical security of access control components is critical to ensuring that a facility is truly secure. Otherwise, the entire system can be...
Access Control Course Fall 2019 - Last Chance on Oct 17, 2019
Register Now - Fall 2019 Access Control Course. Thursday, October 17th is the last day to register. IPVM offers the most comprehensive access...