What Is The Electrical Isolation Procedure?

The electrical isolation procedure is a process that ensures electrical equipment has been safely, securely and properly disconnected from the power source. Following this procedure, the flow of electricity should have ceased, reducing the risk of shocks, fires and other electrical hazards when working with or near electrical systems. It’s a critical component of electrical safety.

Why Is An Electrical Isolation Procedure Necessary?

Carrying out an electrical isolation procedure is essential for ensuring the safety of those working on or around electrical systems. In the UK, it’s a legal requirement under the Electricity at Work Regulations 1989 for electrical systems to be isolated and powered down before being worked on. 

Under the regulations, ‘isolation’ means ‘the disconnection and separation of the electrical equipment from every source of electrical energy in such a way that this disconnection and separation is secure’. Having a standard procedure in place ensures that this can be achieved. 

According to the regulations, the procedure must be carried out and ‘no person shall be engaged in any work activity on or near any live conductor’ unless three distinct conditions have been met:

• It is unreasonable for the live conductor to be dead

• It is reasonable to be at work or near the conductor while it is live

• Suitable precautions have been taken to prevent injury

All three conditions must be met simultaneously to allow for work on live equipment. 

Who Should Carry Out An Electrical Isolation Procedure?

The electrical isolation procedure should be undertaken by the individual scheduled to perform the work. For high-voltage systems – or primary low-voltage systems – this should be a competent person who has been issued a permit by an authorised person. The individual should be trained and have both the knowledge and experience to safely conduct both the procedure and the planned work. 

Types Of Electrical Isolation

There are three forms of electrical isolation that may be used to cease electrical connectivity:

Voltage Isolation

This is the most common form of isolation and involves disconnecting equipment from its power supply. This may include turning off a circuit breaker, removing a fuse or unplugging the equipment.

Power Isolation

Power isolation ensures that all energy sources supplying the equipment are cut off, including any stored energy in the system. It involves disconnecting both power circuits and control circuits.

Galvanic Isolation

This means creating a separation between the power source and the equipment using transformers. It’s mostly used in electronic systems to prevent interference from voltage spikes or electrical noise.

It’s recommended to combine these forms of electrical isolation to ensure the highest level of safety is achieved when working with electrical systems. 

Step-By-Step Guide To The Electrical Isolation Procedure

To safely isolate electrical equipment, a structured and thorough approach is required. Below is a detailed breakdown of the standard steps involved in most accepted electrical isolation procedures:

1. Preparation 

Source Appropriate PPE

Before beginning any isolation procedure, it's crucial to ensure that appropriate PPE is available to protect against potential electrical hazards. The PPE required can vary depending on the type of system and the specific task but may include insulated gloves, arc flash protection and face shields.

Locate The Isolation Point

Identifying where the system can be disconnected from its power source is key. This might involve switching off a circuit breaker, using a main disconnect or unplugging the equipment. This step can be relatively simple in domestic environments but more complex for high-energy systems. 

Post Warning Signs

Danger notices may need to be placed around the work zone to warn others, especially if part of the system remains energised. These signs serve as visual reminders that certain parts of the system are unsafe, helping to prevent accidental exposure to significant electrical hazards.

2. Isolation And Switch Off 

Initiate The Isolation Process

This involves disconnecting the power supply. For low-voltage systems, switching off an isolator or circuit breaker may be sufficient. However high-voltage systems may require more detailed procedures where the act of cutting off the supply and isolating the system involves multiple steps.

Begin The ‘Lockout Tagout’ (LOTO) Process

This ensures that equipment can’t be inadvertently energised while work is carried out. A lockout device applied to the power source prevents anyone from re-energising it, while a tag serves as an extra precaution to ensure the equipment is not operated until the lockout device is removed. 

3. Safety Checks

Verify Isolation

Before beginning any work, it’s essential to prove that the equipment is completely de-energised. This involves using a voltage tester or indicator to check for residual electricity. The tester should be verified on a known live circuit before and after testing to ensure it’s functioning correctly.

Conduct A ‘Dead Test’

After initial checks, a ‘dead test’ should be performed to ensure that no electrical energy is present at the point of work. This confirms that the system is safe to work on. The procedure should be repeated if there’s any doubt. The Health and Safety Executive offers protocols for such a test. 

4. Power Restoration 

Re-Energise The System

Once all work has been completed, the system can be re-energised. Follow the steps of the isolation procedure in reverse, ensuring that all checks are carried out as power is restored to the equipment, leaving the equipment and environment in a safe condition. 

It’s recommended to use a checklist when carrying out the electrical isolation procedure for peace of mind and to confirm that all necessary safety precautions have been followed before starting work. 

The Importance Of Using Safe Isolation Procedures

Implementing the proper isolation procedure is an important safety measure in any role that involves working with electrical systems. Every year, many workers are injured – some fatally – from electrical accidents that could have been prevented had the correct safety protocols been put into place. Following a well-documented and carefully executed electrical isolation procedure ensures the risk of electrical accidents is eliminated, helping to keep everyone safe while working in high-risk settings.