Three steps to foolproof isolation


Published: 05 August 2021

Paul Wilson, UK & Ireland sales manager at Martindale Electric, explains how safe electrical isolation can be achieved and why ignorance is no excuse.

By their very nature, air conditioning and refrigeration systems and equipment rely on electricity and feature a number of electrical circuits. Whilst you may not be required to have a complete set of electrical qualifications to install and maintain this equipment, you most certainly need an understanding of what’s involved, and you must be able to competently and safely isolate such equipment from the electrical supply if you are to work on the equipment. The Health and Safety Executive (HSE) is quite clear that live work should never be undertaken where there is the option to work dead.

By introducing a robust safe isolation procedure, compliance with the latest standards is assured, helping to reduce the number of electricity-related injuries and fatalities within the workplace whilst also avoiding significant financial penalties and consequential losses.

Safe isolation seems relatively simple – you identify the point of isolation, lock it off and label it - but to establish real confidence around your safe isolation procedure, you need to create a more rigorous electrical safety process. And that requires you to prove that the circuit is dead, then verify that the equipment you have used to confirm the circuit is dead is actually working. These are critical components of the overall safe isolation process, so let’s look at each step in more detail.

STEP 1: Identify the point of isolation, lock off and tag

The first port of call is to identify the point of isolation. Before you do anything further, ensure you have gained permission to isolate from this point. It seems obvious, but you’d be surprised how many times this slips people’s minds.

Once permission has been granted, you can lock off and place warning tags onto the equipment.  

Lock-off kits are available to ensure that a suitable locking-off device is always to hand. A basic lock-off kit should include a selection of MCB locks, a padlock with a unique key, a hasp if more than one person is working on a system, as well as lockout tags and warning labels. If an accident were to occur, it’s not enough to say that you didn’t have the right device for the circuit because you could isolate the board. If you can turn equipment off but can’t isolate it at the point of connection, trace the supply back to a point where it can be safely locked off. 

Lock-off tagging systems are an essential safety process for anyone working on or near circuits or equipment. Lock-off devices are a sensible option for all workers. When several people are working in the same area, hasps enable each worker to be allocated their own padlock with its individual, unique key ensuring their safety.

There is no point in proving the circuit dead if someone else comes along and restores power without your knowledge. This can be lethal if you are working on a circuit that is suddenly energised. It can also be dangerous to others, such as a worker cleaning a piece of equipment that suddenly becomes live or starts to operate.

A major problem encountered when working on existing sites is the lack of comprehensive circuit labelling. Even when circuits appear to be correctly labelled, alterations are often made by unqualified or untrained staff. As a result, even if the changes are safe, the labelling may frequently be incorrect.

STEP 2: Use a voltage indicator to check the circuit is dead

No doubt you are familiar with voltage indicators, but not all voltage indicators are equal!

Reliability is key when choosing the right voltage indicator for a particular application, be it for residential projects, commercial or industrial facilities. The best models are available without batteries, ranges, or switches, making them incredibly user-friendly and reducing the opportunity for error (I strongly advise against the use of multimeters here as these can confuse and can be misread).  Ensure the voltage indicator is compliant with HSE Guidance Note GS38, which you can easily do by ensuring that the unit you are purchasing complies with BS EN 61243-3, such as the VI13800 voltage indicator from Martindale Electric which has been specifically designed to meet this standard.

STEP 3: Prove the circuit is dead

It is recommended to use a dedicated proving unit matched to the voltage indicator to test that all LEDs on all ranges are working fully. Check your voltage indicator is working before you test the circuit. A proving unit is safer than the mains and provides a live source wherever you are working. 
The next step is to test for dangerous voltages on any circuit conductor to be worked on, whether single or three-phase. If there is no voltage detected and the circuit is dead, the operator should re-test the voltage indicator using the proving unit. If it’s working correctly, then the operator has proved dead and the system is safe to commence work.

Top tips to stay safe and compliant

With these three steps, it is now possible to ensure full compliance with the latest standards by combining the correct tools for the job with clear and transparent processes.  

To make it even easier and ensure you have the right equipment for the task at hand, I’d recommend investing in a complete safe isolation kit, which brings together all the necessary equipment to prove dead and lockout the circuit being worked on.  These widely available kits - including from Martindale Electric - incorporate the industry standard GS38 voltage indicator, proving unit, and locking off devices in a combination carry case so that the vital proving unit cannot be accidentally left behind. Easy to use, with no need to take the proving unit out of the case, the kits ensure compliance with the latest regulations and legislation.

It's worth investing in a complete safe isolation kit

The other thing to consider investing in is training; it is important to understand what’s required to implement effective safe isolation procedures. Training is readily available through a dedicated training provider. Martindale provides safe isolation educational resources on its website. The training should address the latest standards to ensure compliance and provide industry insight and advice that can be readily implemented.

By creating a complete safe isolation system, ensuring that relevant, industry compliant equipment is always available and used, the margin for error is reduced, and points of failure are minimised. Ultimately, this means reduced risk to life, and that has to be the number one priority.

Martindale Electric