SJUK Exclusive: What’s behind door security?

April 25, 2022


A key factor in the security of any door is control, says Tim Lloyd, Product Specialist, Magnet Schultz Ltd.

A lock is the simplest and most recognisable form of door control – they have been used for centuries. Today, locking technology takes many forms, with locking automation a part of our everyday lives. Whether it be a card or a biometric reader to permit access to a building, the remote locking of a car when leaving it parked or using a smartphone to check-in, the technology behind these functions often goes unnoticed and is taken for granted.

Electromagnetic actuation for locks has been around for well over a century. Some solenoid assemblies still in widespread use have changed little in 50 years or more; one proven design found early favour in the UK as a dependable solution to automatically lock the doors of GPO vans. Some readers will remember that the GPO was responsible for the Royal Mail and the National Telecommunications Service (which became BT in 1980).

Automated locking with a solenoid mechanism provided easy and dependable security for the contents of the van. That Magnet Schultz solenoid was called the Type 61. We now call it the EBL-I, but it’s only the name that has changed to be more meaningful; EBL-I stands for Electric Bolt Lock – Industrial. That same EBL-I electric lock mechanism is now widely used in cash-in-transit (CIT) vehicles for broadly the same security reason. In this application, the lock also provides secondary locking functionality for the driver and passenger.

In applications that provide security for buildings, electric lock mechanisms play a critical role. Solenoid actuated solutions like the EBL-I are found everywhere in access control, in many premises. Among the less obvious applications is security for roller shutters in the distribution hubs of logistics companies and supermarkets. Transport managers can easily prevent access to valuable stock and shipments in loading areas, offering access time slots to loading bays as part of a coordinated logistics strategy. But, this all relies on dependable electric locks.

A high class jeweller in a major British city deploys industrial solenoid lock mechanisms on its entrance doors. Access is controlled from behind the serving counter. Staff can grant access or deny access to keep people out. They can also deny exit to keep people in if things get troublesome!


In an article published by Security Journal UK late last year, we looked at aesthetics as a key consideration for security door mechanisms in some applications. That article covered the Floor Lock, which is mounted beneath the floor surface to remain unobtrusive and virtually invisible.

In many Floor Lock installations, the objective is not to detract from the aesthetics of the premises. The entranceway to Edinburgh University’s 19th Century Old College building, which is the campus reception, is a fine example. As well as being discreet, the Floor Lock features anti-jacking deadlock technology that is a function of its internal mechanisms that comprise a solenoid actuating through a 90° bell crank to raise a 15mm stainless steel pin from the floor that locks a glass door. With that pin actuating in a different plane to the solenoid, force applied to the pin will not cause it to retract.

In other electric locking security applications, the aesthetics of the lock mechanism itself is the consideration. A variant of the robust and popular EBL-I solenoid lock is the Marine Lock (EBL-M). Rather than an open frame construction, the Marine Lock is sealed into a highly polished V4A stainless steel enclosure. It is fully waterproof due to its construction and corrosion-proof to the saltwater environment endured by marine craft.

It is a highly popular lock mechanism that’s widely specified by builders of superyachts. These prestigious craft feature rapid lockdown technology controlled from the helm as a general security measure and specifically as an anti-piracy solution. While counter-intruder security in the event that invaders board the vessel is imperative in some parts of the world, the locking solution must keep up appearances on board multi-million-dollar vessels. The EBL-M Marine Lock is mostly used on internal doors and hatches but is now frequently also deployed on external accessways. It also features anti-jacking technology.

In addition, the EBL-M is the only Magnet Schultz electric lock mechanism that includes a keeper for the strike plate. This enables a simple but effective extra feature that is being increasingly embraced on prestigious craft. The Marine Lock incorporates a reed switch in its housing, while the keeper contains permanent magnets that activate that switch when a door or hatch is closed.

This allows installers to use the switch to send a signal to trigger an event, such as an audio ‘ping’ to denote door activity, or an alarm, or to run a CCTV system whenever the door is opened or closed, even if it’s not locked. Timestamped video adds another dimension to on-board security, providing footage of who opened or closed the door and when.


Among the most familiar security mechanism for doors are straightforward electromagnets. Powerful box magnets are used widely for door holding or release and for locking to provide access control. They can be seen in many shops, supermarkets and office buildings. They are however also widely used outdoors and in more demanding environments, such as marinas, on-board ferries and other vessels and even on oil and gas rigs. In these applications, special qualities are needed.

Most box electromagnets are manufactured to an IP54 rating that provides protection from the ingress of dust and splashing water that could compromise operation. MSL is the only manufacturer to produce electromagnets with IP68 ratings specifically for demanding environments. That’s fully dust tight and more than just weatherproof or splash proof; it’s fully submersible and some applications do indeed use these box magnets under water.

Door security in different forms

Just as locking mechanisms vary, so do the products that constitute a door. Many are guards or gates in installations designed to ensure the security of personal safety. For instance, MSL supplies locking mechanisms that comply with the Machinery Directive and a special TALL (Type Approved Lift Lock) electric lock for lifts that are designed to be type-approvable against the more stringent 2014/33/EU Lifts Directive.

The company is actively seeking a partner to help finalise the testing and approval procedure for the TALL lock. In addition, MSL designs and supplies standard and bespoke electric locking mechanisms for many types of DDA (Disability Discrimination Act) platform lifts that provide disabled or wheelchair access.

While only a percentage of the millions of solenoid actuators produced by Magnet Schultz are deployed in locking conventional doors, MSL solenoids are used in locks by a customer renowned across the industry as a premium security door manufacturer and supplier.

However, the security-centric applications of electromagnet mechanisms address a much broader range of markets and applications that are a constant feature of security and access control in everyday life – as well as unlikely lock variants and applications. One such is a special solenoid door lock used by BT in secure buildings including telephone exchanges. Unusually, this mechanism operates from a 50 Volt supply, taking advantage of the telephone network’s own power system to provide engineers with phone-activated remote access.

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This article was originally published in the April edition of Security Journal UK. To read your FREE digital edition, click here.

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