Access Control in the Energy Sector

Access Control in the Energy Sector

Ensuring the safety of personnel and equipment when accessing hazardous energy areas is imperative. Within the energy sector, maintenance of electrical transmission and distribution equipment often involves multiple power sources to be isolated across the system before personnel can be assured it is safe to enter and they are out of harm’s way. Following a predefined sequence of operations to manage safe access to machinery and electrical equipment is essential for the safety of all involved.

Implementing a trapped key interlocking (TKI) system that has been designed to specific criteria and having the system properly installed, ensures the isolation and earthing conditions can take place under the safest of conditions. A trapped key interlock system provides a visual, physical barrier on switching equipment that indicates the power isolation operations have been completed. A personnel key can also be coordinated into the solution as the last step in the sequence, providing the operator control of the full interlock system until maintenance has been completed and power can be safely restored. Trapped key interlock solutions are flexible enough to be re-configured if the need to incorporate changes to safety procedures arise or if new equipment is integrated into the operations.

Typical examples of access control in the energy sector include maintenance of electrified equipment such as switchgear, capacitor banks, back-up power or ups systems, and transformers.

Benefits of TKI over Alternative Solutions

Electrical interlocking allows for the sequential operation of switches. An example of an application within substations implements an electrical interlocking scheme allowing for the safe operation of disconnects, however, when maintenance activities are being performed, there is a need for a site controlled mechanical device. A mechanical trapped key interlock solution device allows the site operative to complete the sequence of interlock events to release the final authorization key or permission to access key. This final key means that the sequence of operations can only be reversed an controlled by the personnel performing the maintenance activities.

To compare TKI systems to LOTO; LOTO gives the operator control over the environment they are working in and is an effective form of protection. It is a padlock-based/identifiable process that aligns with detailed written operating procedures and signage to visually show the maintenance environment is protected. However, if the procedures are not followed or signage not obeyed, this can cause an unsafe environment on site. Trapped key interlock systems can be integrated within a LOTO procedure or implemented as an alternative method for controlling hazardous energy, as they are recognized by the guidelines of ANSI Z244.1 Integrating a TKI solution can reduce the opportunity for procedures to be skipped or followed out of order, eliminating human error and further mitigating damages.


Access control in energy applications can be far more complicated than other sectors, owing to the fact that it is part of a larger site system with multiple energy sources. The uniquely identified trapped key system provides a full safety system to ensure safe access to multiple power sources and hazardous areas.

KIRK has operated in the energy sector worldwide since in 1932. KIRK products have safeguarded thousands of lives and ensured the safe operation of critical equipment aiding in the efficient operations and maintenance within the energy sector with less down time and higher operational safety.

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