How to operate or service electrical switchgear containing SF6
Source: gov.uk (2025-03-21)

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

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

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

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

There’s separate guidance for manufacturers (https://www.gov.uk/guidance/labelling-f-gas-equipment-you-produce-import-or-install) on how to label electrical switchgear that contains SF6.

Use trained technicians

You must have an F gas (fluorinated greenhouse gas) handling certificate to carry out any activity on electrical 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 electrical switchgear (https://www.gov.uk/guidance/qualifications-required-to-work-on-equipment-containing-f-gas).

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

Check for leaks

SF6 is used in both:
- high-voltage transmission electrical switchgear
- medium-voltage electrical switchgear
You must check your electrical switchgear for leaks if it contains more than 6kg of SF6 unless 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 electrical switchgear contains less than 5kg of SF6, so doesn’t require leak checks.

Most large high-voltage electrical switchgear is fitted with a pressure or density monitoring device, so doesn’t require leak checks. The gas is usually contained in segregated metal enclosures, which can be accessed to perform maintenance.

Operators and service companies share responsibility for preventing SF6 leaks.

How often to check

If you do have to check your electrical switchgear 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
If you install a system to automatically detect leaks, you can double the period of time allowed between leak checks. This may be separate to a pressure or density monitoring device.

If you find a leak

If a leak is found during a check, you must repair it without undue delay and repeat the test within a month to check the repair worked.

Install leakage detection equipment

You must fit a leakage detection system to any electrical switchgear that contains more than 22kg of SF6.

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

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

Keep records

The company operating the electrical switchgear, or the company servicing it, must keep the following records about any electrical switchgear that has leak checking requirements:
- quantity of SF6 in the electrical switchgear when it’s installed
- quantity of SF6 added during any maintenance (for example, installation or leak repairs)
- quantity of SF6 recovered during any maintenance (for example, decommissioning at end of life or leak repairs)
- details (name, address and certificate number if relevant) of any companies that work on the electrical switchgear
- dates and results of all mandatory leak checks
- measures taken to recover SF6, and the quantity recovered, when you decommission the electrical switchgear
- measures taken to recover and dispose of gases
- if the gas is recycled or reclaimed and the facility that recycled or reclaimed it
If your technician adds recycled or reclaimed SF6 to your electrical switchgear, 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.

Recovery of SF6

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

You must employ someone with an F gas handling certificate for work on electrical switchgear (https://www.gov.uk/guidance/qualifications-required-to-work-on-equipment-containing-f-gas) to do this.

The qualified technician that you hire will discuss the options for reusing or destroying recovered SF6 (https://www.gov.uk/guidance/recovering-reclaiming-and-recycling-f-gas).