Last reviewed 2 December 2021

The Health and Safety Executive (HSE) has granted a legal exemption that will enable the use of more environmentally friendly gases in the electricity distribution network.

With full details available at, and in effect from 1 December 2021, the exemption is applicable to any pressure system containing an insulating and interrupting gas and forming an integral part of high voltage (HV) electrical apparatus.

It will remain in force for five years and will then be reviewed.

The decision was made by HSE’s Product Safety and Market Surveillance Unit, which acts as a policy lead for Pressure System Safety Regulation 2000 (PSSR), after it was approached last year by the Energy Network Association (ENA), the body representing energy suppliers in the UK.

The PSSR aims to guarantee safe design and use of pressure systems, including high voltage pressurised units, that form part of the electrical network across the UK, and that are critical to maintaining supply.

Current regulations include an exception, which effectively exempts application of PSSR to high voltage apparatus which have been manufactured to remain sealed, and which contain sulphur hexafluoride (SF6) — an extremely potent and persistent greenhouse gas (GHG), with warming potential 23,900 times that of carbon dioxide (CO2) and with atmospheric residence of up to 3200 years.

Facing increasing restrictions and potential international bans on the use of SF6, leading manufacturers are beginning to develop new designs of high voltage electrical apparatus using alternative gases with significantly lower global warming potential.

The ENA requested that the exception be extended to include other gases which meet the same technical and safety criteria offered by SF6.

Luke Messenger, an inspector from the Product Safety and Market Surveillance Unit said: ‘’The new exemption removes a barrier to technical progress thereby facilitating the removal of SF6. It will help level the playing field amongst the network operators and will bring equipment user legislation (Pressure Systems Safety Regulations 2000) in line with product supply legislation (Pressure Equipment Safety Regulations 2016)”.