How to operate or service high voltage switchgear containing SF6

Requirements for businesses that operate or service high voltage switchgear that contains sulphur hexaflouride (SF6).


Department for Environment, Food & Rural Affairs and Environment Agency


1.     Types of switchgear

2.     Use trained technicians

3.     Check for leaks

4.     Install leak detection equipment

5.     Keep records

6.     Recover SF6

Sulphur hexaflouride (SF6) is used to insulate equipment in the electricity industry like circuit breakers, switches and transformers.

You operate switchgear if you’re in charge of the day-to-day running of the equipment. You don’t have to own the equipment to be the operator.

You’re a service company if you maintain switchgear, for example if you install equipment or repair leaks.

There’s separate guidance for manufacturers on how to label switchgear that contains SF6.

Types of switchgear

SF6 is used in both:

·         high voltage transmission switchgear

·         medium voltage switchgear

High voltage transmission switchgear often contains hundreds of kilograms (kgs) of SF6. The gas is contained in segregated metal enclosures, which can be accessed to perform maintenance.

Medium voltage switchgear typically contains less than 5kg of SF6. The gas is often sealed within the equipment. You don’t have to maintain SF6 if it’s sealed inside equipment.

Use trained technicians

You must have an F gas (fluorinated greenhouse gas) handling certificate to carry out any activity on switchgear that involves handling SF6. That includes:

·         installation

·         maintenance and repairs

·         recovery of SF6

·         ‘decommissioning’ equipment at the end of its working life

Find out how to get an F gas handling certificate for work on high voltage switchgear.

Service companies are responsible for making sure their staff have proper qualifications.

Check for leaks

You must check your equipment for leaks if it contains more than 6kg of SF6unless either of the following apply:

·         it has a pressure or density monitoring device

·         the manufacturer has tested it to show it has a leakage rate of less than 0.1% per year, and labelled it to confirm this

Most medium voltage switchgear contains less than 5kg of SF6, so doesn’t require leak checks.

Most large high-voltage swithgear equipment is fitted with a pressure or density monitoring device, so doesn’t require leak checks.

Operator and service companies share responsibility for stopping SF6 leaks.

This is a requirement from 1 January 2015. You didn’t have to check high voltage switchgear for leaks under the 2006 regulation.

How often to check

If you do have to check your equipment for leaks, you must do this every:

·         6 months if it contains between 6 and 22kg of SF6

·         3 months if it contains more than 22kg of SF6

You only have to check for leaks half as often if you install a system that automatically detects them.

If you find a leak

If a leak is found during a check, you must repair it and repeat the test within a month to check the repair worked.

Install leak detection equipment

You must fit a leak detection system to any equipment installed after 1 January 2017 that contains more than 22kg of SF6. The operator is responsible for making sure the system is fitted.

The leak detection system must alert the operator or service company if a leak is detected.

You must have your leak detection system checked at least every 6 years to make sure it’s working properly.

This is a requirement from 1 January 2015. You didn’t have to install leak detection equipment on high voltage switchgear under the 2006 regulation.

Keep records

The company operating the switchgear, or the company servicing it, must keep the following records about any equipment that has leak checking requirements:

·         quantity of SF6 in the equipment when it’s installed

·         quantity of SF6 added during any maintenance (eg installation or leak repairs)

·         quantity of SF6 recovered during any maintenance (eg decommissioning at end of life or leak repairs)

·         details (name, address and certificate number if relevant) of any companies that work on the equipment

·         dates and results of all mandatory leak checks

·         measures taken to recover SF6, and the quantity recovered, when you decommission the equipment

If your technician adds recycled or reclaimed SF6 to your equipment, you or your contractor must record the following details about the recycling or reclamation facility:

·         name

·         address

·         certificate number

You must keep records for 5 years and make them available to inspectors if they ask for them.

The following requirements weren’t in the 2006 regulation:

·         recording measures taken to recover and dispose of gases

·         recording if the gas is recycled or reclaimed and the facility that recycled or reclaimed it

Recover SF6

You must recover SF6 when your service high voltage switchgear and before you dispose of high voltage switchgear that you’re decommissioning.

You must employ someone with an F gas handling certificate for work on high voltage switchgear to do this.

The qualified technician that you hire will discuss the options for reusing or destroying recovered SF6.

Published 31 December 2014


Q200,Ultra High Sensitivity SF6 Trace Gas Leak Detector,as the quantitative leak detector, as the main detection instrument of SF6 gas leakage of high-voltage switch, transformer and other SF6 equipment, has long been used by switch manufacturers,and various power operating units are used in the factory inspection, acceptance installation and daily leak detection of SF6 electrical equipment. Its high sensitivity (10-8 mL/S (0.01 PPM) and stability make up for the inadequacy of imaging leak detector (accuracy 10-3 mL/S (1000PPM) which can not locate the single point leakage.


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