MOBs Phase 3: Task 8 - Electrical Safety Report

There is a requirement for gas distribution network (GDN) operators to understand the cost, safety, and practicality of converting network pipelines from natural gas to hydrogen in multi-occupancy buildings (MOBs). Previous work undertaken during project “MOBs Work Pack 2 Asset Information Review” [1] considered the requirements for domestic electrical safety in MOBs following a conversion to hydrogen and identified gaps in technical evidence.
SGN is leading a feasibility project with some applied testing to understand the steps needed to convert MOBS to Hydrogen. Task 8 relates to potential electrical safety requirements associated with the conversion of MOBs from natural gas to hydrogen. It was proposed that ROSEN review the projects “EUSE – Hazardous Areas Within Buildings” [2] and “ATEX Equipment & SR/25 Modification Assessment” [3], to confirm their applicability to MOBs. The objectives of this review are to:
1. Confirm whether the standards to which electrical equipment is currently specified relates to natural gas only, or to any flammable gas
2. Determine whether requirements for electrical equipment are impacted by hydrogen being gas group IIC versus gas group IIA for natural gas
3. Investigate whether the existing separation distance between natural gas pipes/meter and electrical equipment remains the same with hydrogen.
ROSEN has reviewed the outputs from these research projects, as well as relevant standards to determine electrical safety requirements for the conversion of MOBs from natural gas to hydrogen.
The review of standards and research projects undertaken has drawn the following conclusions in regards to electrical safety.
1. To comply with the requirements of DSEAR, meter banks, energy centres and common areas within MOBs must be risk assessed to determine the location and extent of explosive atmospheres and their classification once repurposed for use with hydrogen. The risk assessment includes hazardous area classification of the pipework and components.
2. For pure hydrogen, the necessary air change rate per hour to allow classification as Zone 2 NE is increased from 0.5 (for natural gas) to 1.5 air changes per hour (ACH). Where this cannot be achieved, uncertified electric lighting and other electrical equipment will need to be relocated or replaced with certified gas group IIC equipment.
3. There will be no requirement for a hazardous area classification for hydrogen in a domestic environment (individual dwellings) as DSEAR does not apply.
4. The minimum separation distances between electrical equipment and gas equipment are independent of the gas being transported and research projects have concluded that these do not need to change.
5. Lightning protection requirements are independent of the gas being transported, and are in place to protect the pipe structure from damage and existing IGEM/G/5 guidance can remain unchanged.
6. Research indicates that most incidents relating to electrical safety are due to non-compliance with current standards.
7. Any electrical equipment located in the vicinity of gas installations should be assessed for compliance by a competent person, prior to the conversion of MOBs to hydrogen.
This report was submitted to HSE for their assessment of the safety evidence for 100% hydrogen heating, which can be found at Hydrogen heating: HSE assessment of the safety evidence - GOV.UK.
Queries should be directed to DESNZ: https://www.gov.uk/guidance/contact-desnz.