Anyone who works with electrical installations as part of their job should be able to understand and apply the safe isolation procedure. This post explains what safe isolation is, the purpose behind it, and the steps involved in isolating an installation from a live supply.

Testing a socket with an electrical meter

 

What is Safe Isolation in Electrical Work?

When working on an electrical installation, it’s vital that you disconnect it from the live supply and test whether any current is running through it before making a start on the task at hand. In the electrical trade, this process is referred to as safe isolation.

Once you’ve disconnected an installation from the rest of the circuit and checked that no current is flowing through it, the system is said to be “dead” (as opposed to “live”). At this point, you can safely start investigating and fixing the installation.

We isolate systems from the rest of the circuit prior to working on them primarily for safety purposes: if part of the installation is still live (i.e. connected to the mains supply), then you and other people on site run the risk of receiving an electric shock and serious burns.

The most common way to disconnect an electrical installation is to use the main switch, which controls the supply of electricity to a property. Once you’ve done this, you’ll still need to test the system properly before you start to carry out any work.

Consumer unit

Source

The rules on how you should safely isolate and test an electrical system are set out in the Electricity at Work Regulations and BS7671 (the 18th edition wiring regulations). To save you some time, however, we’ve provided a complete breakdown of the safe isolation procedure and the equipment you’ll need below.

 

The Safe Isolation Procedure

Isolating an electrical installation by disconnecting it from the mains supply is just one part of the safe isolation procedure. There are also a number of other stages involved, such as obtaining permission to carry out the work beforehand and testing the voltage of the installation afterwards.

Before looking more closely at these other parts of the process, we should first run through all of the equipment that you’ll need to isolate the system in the safest possible way and ensure that you comply with the current regulations.

 

What You’ll Need: Safe Isolation Equipment

It’s important that you have all of the right equipment at the ready before you begin. The easiest way to get hold of the parts you need is simply to buy a safe isolation kit, which should contain the following items as a minimum:

  • 1 x voltage detector
  • 1 x proving unit
  • 2 x grip tight MCB (main circuit breaker) lockouts
  • 2 x mini circuit breaker lockouts
  • 1 x safety padlock and key
  • 2 x safety lockout ID tags
  • 1 x steel lockout hasp

You can purchase a safe isolation kit directly from the NICEIC.

 

Safe Isolation Procedure: Step-by-Step Guide

The steps involved in the safe isolation procedure are as follows:

  1. Obtain the required permission to work on the installation (this will depend on the type of work and whether you’re working in a domestic or commercial setting).
  2. Identify the source(s) of supply using the voltage detector or test lamp.
  3. Test your voltage detector or test lamp to make sure that it is working properly.
  4. Isolate the supply, disconnecting the system from the mains.
  5. Secure or “lock off” the isolation using your safety padlock, preventing any tampering.
  6. Use your voltage detector or test lamp to determine that the system is dead.
  7. Prove that your voltage detector or test lamp is functioning correctly as you did in step 2.
  8. Put up clearly visible warning signs to indicate that the installation has been isolated.
  9. Once you’ve confirmed that the system is dead – i.e. there is no current flowing through it – work can begin.

 

Key Takeaways

We’ve covered a lot of material over the course of this post, explaining the concept of safe isolation; the tools you’ll need to use, and the safe isolation procedure itself. With this in mind, here are a few key takeaways to help you remember it all:

  • Safe isolation refers to the process of disconnecting an electrical installation from the rest of the circuit and testing that no current is flowing through it.
  • The purpose of isolating an installation is to ensure the safety of the people who are working on it, preventing them from receiving an electric shock.
  • The most common way to disconnect a system is to use the main switch (also known as the isolator switch).
  • All of the equipment you need can be purchased in the form of a safe isolation kit.
  • The safe isolation procedure is not just about disconnecting the system and testing whether it is dead; there are nine steps involved in the process in total, as outlined above.

 


This guide has provided an introduction to the safe isolation procedure and explained how it should be carried out in accordance with the regulations. If you’d like to learn more, take a look at our safe electrical isolation course or get in touch today.