Electrical thumb rules for switching, isolating and earthing

Guidelines to proper switching, isolating and earthing

It is essential that the electrical engineers, or operators who will be in charge of switching, isolating, and earthing operations of the switchgear have a good understanding of the rules that must be followed. In addition, it is of the utmost need to guarantee that the operator and the substation are both safe during the execution of these tasks.

The most effective way for accomplishing this is through meticulous planning, as well as the documentation of both the procedures and the safety precautions undertaken.

However, this isn’t always the case, as engineers or individuals unfamiliar with the procedures often perform operations like switching, disconnecting, isolating, or earthing. Inexperienced engineers and technicians can also make critical mistakes while operating in a power substation.

Let’s dive now into the rules!

Table of Contents:

1. Who’s Authorised To Operate Electrical Equipment
2. Switching Operation and Personal Safety
3. General Switching Rules
4. Declaring “Out of Commission”
5. Earthing Before Performing ANY Work
6. Electrical Access And Authorities
7. Sanction For Testing Procedure
8. Barriers and Signs (Live Electrical Equipment)
9. Attachment (PDF) ✅ – Modern substation condition monitoring strategies for switchgear, transformers and cables

1. Who’s Authorised To Operate Electrical Equipment

Thumb Rule №1 – Switching and associated duties on electrical equipment MUST be performed by either Electrical Operators or engineers whose training, duties and instructions cover the particular electrical equipment.

However, any engineer who has the ability may perform operations in the following circumstances:

1. When explicitly directed by, or permitted by the relevant Operating Authority.
2. In a critical situation posing significant danger to individuals or assets.

Thumb Rule №2 – All switching must be directed and controlled by the appropriate Operating Authority.

Figure 1 – Substation engineer performing an operation of racking-in breaker

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2. Switching Operation and Personal Safety

Thumb Rule №1 – When operating electrical equipment, you must:

1. Wear certified protective headgear and clothing
2. Wear certified and appropriate eye protection.
3. Wear certified insulating sole footwear.
4. Only use devices to open circuits under load that are capable of interrupting the current involved.
5. Avoid contact with ANY earthed conductive equipment.

Thumb Rule №2 – When engaging with electrical equipment through a metal handle (such as racking-in or racking-out rackable metal clad switchgear breakers), it is essential to put on suitable insulated gloves that are routinely tested and maintained, along with one of the following:

1. An insulated platform (e.g. ladder, EWP).
2. A high-voltage mat.
3. Two interleaved low-voltage mats.
4. A high-voltage operating sleeve (appropriately tested and maintained).

Thumb Rule №3 – When operating electrical equipment via operating sticks, they must be:

1. Of the appropriate length for the voltage involved.
2. Appropriate for the task involved.
3. Appropriately tested, maintained and within test date.

Watch Video – Operating switchgear using hookstick

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3. General Switching Rules

Thumb Rule №1 – When switching any substation equipment the following must apply:

1. To avoid ANY misunderstandings, switching instructions issued over the radio, by phone, or in person should be repeated for confirmation. The equipment and its label must be described in sufficient detail to allow for absolute identification.
2. After operating a piece of equipment, the operator must confirm the equipment’s status (OPEN, CLOSED, DISCONNECTED, EARTHED)
3. Appropriate tags must be attached to all switches and/or control circuits operated to de-energise equipment or line sections on which an Access Authority is required.
4. If during the course of switching a piece of electrical equipment it is found to be defective it must be reported to the appropriate control centre or authorised individual and an appropriate tag attached.
5. Employees must not remove or alter in any way, without consulting the operating authority or individual who attached the tag, any tags that have been applied to a device.

Thumb Rule №2 – For the purposes of identification, wherever practicable, electrical equipment must be clearly labelled.

Figure 2 – An operator wearing proper clothing and gloves working on Low-voltage equipment

Thumb Rule №3 – Before making any substation equipment alive, the operating authority must ensure that:

1. In the case of new equipment, all necessary clearances have been verified by the operator. This can also include certificates for electrical certification for HV customers.
2. Any Access Authorities, or other documents pertaining to the equipment have been cancelled.
3. The results of any pre-activation tests required to be carried outon the equipment are satisfactory.
4. All earths are removed and a visual inspection shows that to allappearances the equipment is ready for service.