Demystifying Control of Work

Demystifying Control of Work – The Terminology

ISSoW, SSoW, CoW, PTW, HIRA, JSA, TRA and LOTO. What do they mean and what is the difference between each? Is ISSoW CoW? Is CoW the same as PTW? Should you adopt HIRA or a TRA or maybe even a HITRA?

Is ISSoW CoW? Is CoW the same as PTW? Should you adopt HIRA or a TRA or maybe even a HITRA? These acronyms are thrown around on a daily basis and are enough to bewilder any novice, and even some of the more experienced bunch can struggle to give concise definitions.

Integrated Safe System of Work (ISSoW) and Control of Work (CoW) are essentially the same.  They are management systems.  They manage all work on operating and/or shut down facilities.  They comprise Risk Assessment, Permit to Work, Energy Isolation Management and Lock Out Tag Out, or LOTO as it is commonly called. Both can be deployed electronically, as a paper-based system or even a hybrid combination of the two.

Cresent’s Control of Work system, WorkSafe®, has a systematic approach that forces rigour when planning, authorising and performing work.  This is essential to assure work is performed with the least risk to the facility, to the people, and to the environment.

The system should comply with, or exceed the expectations of:

Within this, and depending on the operational complexity and facility size, there are numerous sub-systems that cannot be ignored such as confined space entry, working at height, diving and scaffolding etc.  In addition to this, there are essential influencing factors which must be taken into consideration such as Electrical Safety Rules (legal requirement) and process isolation standards which, although not legal requirements, are absolutely essential.

Demystifying Control of Work


Whilst often synonymous with CoW, PTW is its own entity.  Permit to Work (PTW) is a formal process used to control certain types of work which could cause potential danger.  Permits clearly communicate what, where and when work is required, along with who can authorise the job and who will carry out the job.  You’ll often hear people refer to a CoW system as simply a Permit to Work system, but it is important to remember that the two are different.

In principle, Hazard Identification and Risk Assessment (HIRA), Job Safety Analysis (JSA), Task Risk Assessment (TRA) and Hazard Identification and Task Risk Assessment (HITRA)are more or less identical processes used to identify any potential hazards relating to a task.  This process facilitates the selection and implementation of relevant controls to mitigate the hazards by reducing the residual risk from each hazard to as low as reasonably practicable (ALARP).  Dynamic Risk Assessment (DRA) is then used to continue the identification of hazards and the assessment of risk throughout the task to spot any new or previously unforeseen hazards.


Lock Out Tag Out (LOTO) is the segregation of energy sources from by creating a secure isolation.  It ensures that equipment is wholly isolated by creating a safe environment which cannot be inadvertently de-isolated during task execution.  There are a variety of methods used to achieve and communicate individual isolations such as locks, hasps and tags which are all important, but it is the LOTO system that manages this.

CoW systems, and their subsystems or modules should all have the ability to be tailored to suit operational and organisational requirements.  This can range from the user interface to company-specific terminology being delivered in any language with even the ability to ‘toggle’ between languages to suit an international workforce. This is a key feature of WorkSafe®.

Whilst electronic Control of Work (eCoW) systems, like WorkSafe®, boast an array of advantages such as streamlined processes, improved legibility and automatic integration between PTW, HITRA & LOTO, paper is still applicable and appropriate for some operations.  The decision should be made on a facility-by-facility basis and never seen as one-size-fits-all.  This should all be thoroughly analysed during the first stage of CoW: system requirements specification.

It is crucial to remember that the success of your system is only as good as the people using it.  Control of Work system providers should be experts in the field with a well-documented background in health and safety system design and configuration with a genuine passion to make work safe.

If you are planning to move from an older existing system to a new and electronic CoW system then this is a management of change (MoC) project involving technology and people.  The technical aspects are by far the easiest to manage and to predict the effect the change will have.  Training, as well as more general communication, should be thoroughly planned, prepared and delivered in a variety of methods and personalised to suit the prevailing safety culture.  Good quality training increases organisational knowledge retention, individual system user confidence and easier acceptance of the change by the end user.  Delve a little deeper and invest in role-based training: a programme designed specifically for individual roles and responsibilities.  It helps to ensure excellent Return On Investment (ROI).

Control of Work is complex subject with a multi-discipline impact that deserves the appropriate investment of both time and money.  It does, however, pave a path to better safety performance, workforce engagement as well as improved productivity and operating cost savings.  To find out more about Control of Work, and our associated services, speak to one of our experts today.


Hopefully, the different terminology associated with Control of Work all makes sense now.

If you’re still looking for some additional assistance why not take a look at our Introduction to Control of Work e-learning course. Alternatively, get in touch at and one of our team will be able to assist.

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