Safe isolation procedures and using the correct equipment can help prevent workers being exposed to danger when working on or near live electrical systems. Failure to use correct procedures could result in a circuit inadvertently remaining live, potentially resulting in serious injury. The 5 key questions below give a basic overview of safe isolation considerations.

1) Why do I need Safe Isolation?
Safe isolation procedures are necessary to ensure workers on site are not exposed to danger when working on or near live electrical systems. Electrical Safety First, in association with other industry bodies, such as SELECT, has produced a document that covers best practice for safe isolation (Best Practice Guide 2 Iss.3 2015). This includes guidance on proving isolated equipment or circuits are dead, using suitable test lamps and voltage detectors.

2) What equipment is required for safe isolation?
The point of isolation should be locked off using a unique key or combination, retained by the person carrying out the work or appointed person, and a caution notice attached to the point of isolation. Locking off the circuit is just one part of the procedure. Before carrying out any work, it’s essential to verify that the circuit is definitely dead. Circuits are frequently mislabelled, so there is no certainty that the correct circuit is locked off. To do this, you should use a dedicated voltage indicator and a proving unit.

3) What is the correct equipment to use for proving dead?
You should use a dedicated voltage indicator and a proving unit when carrying out this procedure. Equipment must comply with BS EN61243. It is important to note that the voltage indicator MUST function without the need for a battery. If you are using a device that needs a battery in order to work and the battery is flat, you will not be able to prove if the circuit is dead or not.

4) Why can’t I use a multimeter or non-contact voltage detector to prove dead?
The use of multimeters or non-contact voltage detectors is advised against in the HSE guidance. For multimeters, it is very easy to select the wrong range, plus they rely on battery power to function, thus there is a high risk of making a false “dead” reading on a live circuit. Non-contact voltage detectors also require a battery in order to work and are often sensitive to other signals, such as static electricity. It’s also not possible to prove they are working correctly with a standard proving unit. Whilst these units can be used to detect live cables, they cannot reliably be used to prove dead.

5) How can I find more information?
These questions have only briefly touched on safe isolation procedures, further information can be found in the HSE’s publication Electricity at Work – Safe Working Practices (HSG85), the ESF Best Practice Guide 2 or guidance and resources at With guidelines well established and safe isolation kits readily available, implementing safe isolation procedures is neither difficult nor expensive and has been proven to save lives and avoid injury. It’s essential for compliance with Electricity at Work Regulations for safe working when installing and maintaining electrical equipment and systems.