Compliance
Gas Interlock Regulations & the Law
In a commercial kitchen with mechanical ventilation, BS 6173 requires a means of preventing gas use unless ventilation is proven. In practice that means a gas interlock, and an inspector will expect to see one.
- BS 6173 — installation of gas-fired catering appliances
- IGEM/UP/19 — design and application of interlock devices for gas safety
- Gas Safety (Installation and Use) Regulations 1998 — the duty on the responsible person
Who needs one
- Commercial kitchens with mechanical extract serving gas catering appliances
- Restaurants, pubs, hotels, schools, care homes, hospitals and staff canteens
- Mobile and modular catering units with gas appliances and forced ventilation
- Plant rooms where gas detection is used to isolate the supply automatically
What an inspection looks for
| Check | Expected |
|---|---|
| Interlock present and functional | Gas cannot be used with ventilation off |
| Emergency shut-off | Latching e-stop in an escape route position, tested |
| Valve type | Normally closed — fails safe on power loss |
| Records | Commissioning certificate and annual test record |
| Ventilation performance | Extract and make-up air rates suitable for the appliance gas load |
Who is responsible
The duty sits with the responsible person for the premises — the operator, landlord or facilities manager — not the chef. Insurers and environmental health officers routinely ask for the interlock test record alongside the gas safety certificate.
Frequently asked questions
Is a gas interlock system a legal requirement?
The Gas Safety (Installation and Use) Regulations require commercial gas installations to be safe, and BS 6173 sets the accepted way to achieve that where mechanical ventilation is fitted — an interlock. If you have mechanical extract and gas catering appliances, treat it as required.
Do I need an interlock if my kitchen has only natural ventilation?
An interlock proves mechanical ventilation, so a genuinely naturally ventilated kitchen is a different assessment. Have a commercial engineer assess the ventilation against the appliance gas rating before assuming an interlock is unnecessary.
What is CP42?
CP42 is the Gas Safe Register code of practice covering the safe use of gas in commercial catering, including ventilation and interlock requirements.
How often must the interlock be tested?
At least annually, and after any alteration to the gas installation or the ventilation system.
Related guides
Gas Interlock Systems
The pillar guide: how interlocks work, standards and fault-finding.
Servicing & Testing
Annual interlock testing, certification and planned maintenance.
Commercial Kitchen Gas Safety
Ventilation interlock, airflow proving and CP42 compliance.
Interlock Installation
Kit selection, 28mm and 35mm valves, wiring and commissioning.
Gas Proving Systems
Pressure proving panels, operating sequences and commissioning.
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