Tagging Along – the importance of lockout and tagout procedures

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Lockout and tagout (LOTO) processes are vital in some sectors for life safety and for protecting investments made in machinery and other equipment.

LOTO is often seen as a rather technical process — something that, incorrectly, can be seen as part of risk assessment simply to be followed up afterwards as an operational control.

There are successful prosecutions arising from LOTO: for example, HSE v BW Riddle (2014) in December 2014, where the defendant received a £70,000 fine plus costs for an incident involving an inadequately isolated conveyor belt that led to an employee being injured. This is just one case involving LOTO.

In other words, LOTO is not something to be left just to the experts, especially as there may be different national standards and indeed, different technical opinions as to the best way to apply LOTO.

What is LOTO?

Lockout and tagout is a system or protocol for isolating energy sources before the inspection and maintenance of equipment. In short, it can prevent accidents and prevent unplanned damage to machinery and the processes it supports.

Depending on the circumstances, LOTO prevents operation of such equipment whilst it is under repair, out of commission or where it is only for use for certain groups or shifts. It can also be used to isolate the energy sources to, for example, a piece of machinery without any physical safety risk that could be involved in isolating the machine itself. In other words, following on from these processes, LOTO then prevents the accidental use of such equipment or unauthorised staff from operating it.

LOTO can encourage wider safe operating procedures; because LOTO will require a clearly defined protocol, staged from shutdown through to maintenance, this can encourage a review of the safe systems of work present at each stage of the LOTO process.

In terms of isolating energy sources, LOTO can have wider applications than just isolating electricity — it can used any part of industrial process, e.g. isolating feedstock into a process. This can include the so called “hot processes” often found in the petrochemicals sector, involving liquids and gases under pressure.

Similarly, LOTO can be adapted for more research-based scenarios where risk assessments may include concerns about novel processes or uncertain outcomes or simply where the veracity of experiments need to be established. LOTO can help provide this by ensuring a restricted number of authorised personnel can have access to key equipment and devices producing such results.

A recommended staged LOTO process is as follows:

  • Prepare for shutdown
  • Inform employees
  • Turn off equipment
  • Isolate energy sources
  • Perform maintenance
  • Test all circuits
  • Test the equipment controls
  • Lock off switches.

Of course, this may need to be adapted to individual circumstances, but it shows the importance of a safety process, effective communication, competence and awareness of all energy and feedstock sources are vital. These have wider safety benefits than just LOTO.

Where electrical isolation is used as one of the main tasks of LOTO, there needs to be careful checking of all energy sources. This may sound obvious, but circuit diagrams and other understandings make not always be fully correct, especially in older business premises — and LOTO can only fully isolate or inform when these sources are fully understood.

The same principle applies with second hand machinery or machinery designed for operation outside the UK — the use of energy sources and safety by design needs to be fully understood in accordance with UK practice before applying LOTO principles.

iStock_000029306606_FullThe only control?

LOTO may not be the only control to prevent access to equipment that is undergoing maintenance. Some machinery is devised not to operate when certain key components are immobilised or isolated during maintenance; equally, as the majority of machinery and devices have an element of computer control within them and so a “fail safe” is programmed within to respond to any identified malfunction. On a larger scale processes, there may be supervisory control and data acquisition (SCADA) systems which have similar functions and additionally will deploy early warning and real-time process information that makes the accidental deployment of isolated equipment more unlikely.

As with all controls, including safety by design and SCADA-type systems, it is important to understand what the limitations, rather than focusing on what the control will do. For example, tag off is often used with SCADA systems to record safety status on individual values or control panels.

Types of LOTO equipment

In broad terms, LOTO kits falls into the following broad categories.

  • Conventional lock boxes and bags. These can used to store safety critical equipment at site level with access only to authorised persons – in remote locations this may include storage of the LOTO equipment. Locking such equipment away minimises the risk of it being used by unauthorised personnel who have not, perhaps, properly isolated the equipment
  • Lockout devices. These can actually isolate (or otherwise) the machine or feedstock. Examples include electrical lock out, value lock outs, cable lock out and cylinder lock outs. They can be designed for the specific machine concerned or be more generic, and specialist advice needs to be taken in selection.
  • Padlocks, hasps and ties. In addition to specific lock out devices, padlocks, hasps and ties can be used in a number of LOTO scenarios, often with accompanying tags, but please note that there are many different configurations and applications.
  • Tags and signs. These provide information to employees and record key facts such as when the lock out took and by whom. Again, these can be colour-coded especially where is there is more one lock out authority, i.e. different staff doing their own maintenance regimes on the machine concerned.



In almost every application involving machinery and large devices, LOTO needs be considered. Sometimes it is the only solution to maintain compliance and promote safe working.

As with many aspects of operational controls, safe systems of work should never be assumed. Implementing LOTO procedures may highlight other areas of improvement within the safety process. Specialist advice will often be indicated to ensure that the most appropriate LOTO devices are employed for the task in hand.


Disclaimer: The information provided through Legislation Watch is for general guidance only and is not legal advice. Legislation Watch is not a substitute for Health and Safety consultancy. You should seek independent advice about any legal matter.

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