A commercial kitchen gas interlock links the availability of gas to safety conditions associated with the kitchen ventilation and, where applicable, air quality. If the required conditions are not proved, the system prevents or isolates the gas supply. The exact design must follow the current standards and be specified and commissioned for the actual installation.
Why the gas and ventilation systems are connected
Gas-fired catering appliances need adequate combustion air and safe removal of combustion products. Commercial kitchens also require ventilation to capture heat, steam, grease, smoke and cooking odour.
If mechanical ventilation stops or performs inadequately, continuing to operate the gas cookline can create unsafe conditions. An interlock reduces the risk of appliances operating without the required supporting ventilation.
The HSE advises employers to make sure the gas supply is interlocked with the ventilation of relevant commercial plant and to provide enough ventilation to remove combustion products: HSE gas safety for employers.
The main documents
Two technical references are central:
- BS 6173:2020, covering installation and maintenance of gas-fired catering appliances.
- IGEM/UP/19 Edition 2, covering design and application of interlock devices and associated systems in commercial catering gas installations.
IGEM states that UP/19 was developed with Gas Safe Register and the catering industry. Its scope includes air-flow and air-quality interlock devices for new commercial catering establishments and considerations for replacement or extension work.
These are standards, not a DIY wiring guide. The installation needs input from a suitably qualified commercial catering Gas Safe engineer and coordination with the ventilation and electrical/control designers.
What the system may include
Depending on the design, a complete arrangement may include:
- gas isolation valve;
- interlock control panel;
- means of proving extract and/or supply air performance;
- air-quality monitoring where required by the current design standard;
- fan status and fault signals;
- start-up and reset sequence;
- emergency gas isolation;
- connection to fire or other safety systems where specified;
- alarms or indicators that tell the operator why the system has not enabled gas.
The important word is proving. A fan power light or the sound of a motor does not necessarily demonstrate that the required air movement is being achieved.
Does every commercial kitchen need a gas interlock?
An all-electric kitchen has no gas supply to interlock. For a kitchen with gas catering appliances and mechanical ventilation, interlocking is a core design and gas-safety consideration.
Existing or unusual installations should not be judged from a generic internet rule. IGEM/UP/19 has provisions and risk-assessment considerations that need competent application. Changes to the cookline, ventilation system, gas valve or controls can also trigger a review.
Ask the responsible Gas Safe engineer to document what applies and why.
Airflow proving and air-quality monitoring are different
Airflow proving checks whether the ventilation system is delivering an appropriate operating condition. Air-quality monitoring looks at conditions within the space.
Neither should be casually substituted for the other. Sensor position, set-up, maintenance, failure modes and the start-up/shutdown sequence all affect safety. Use the arrangements required by the current standard and the competent engineer's design for the installation.
Common interlock failures on projects
Controls are ordered before the design is agreed
A generic panel is purchased before appliance type, fan arrangement, valve size and proving method are confirmed. The site then has to adapt around the product.
The fan is “proved” only by an electrical signal
A run signal can exist while a belt, damper, filter or duct problem prevents the intended airflow.
Replacement air is omitted
Proving extract alone does not solve excessive negative pressure or inadequate air replacement.
The gas valve or pipework is treated as an electrical accessory
Valve selection, location and gas installation work belong within the competent gas design and installation.
Nobody owns commissioning
The ventilation contractor tests the fans, the electrician powers the panel and the gas engineer checks appliances, but nobody demonstrates the whole safety sequence under normal and failure conditions.
Operators bypass nuisance trips
Repeated trips are a fault or design signal. Bypassing the interlock removes a safety function and should never become the operational fix.
What should be demonstrated at handover?
The project team should agree a witnessed test that shows, as applicable:
- normal start-up sequence;
- required ventilation conditions being proved;
- gas becoming available only when permitted;
- response to loss or failure of ventilation;
- response to relevant air-quality conditions;
- operation of emergency isolation;
- correct reset behaviour after a trip;
- clear fault indication for staff;
- interaction with any fire or building controls included in the design;
- safe operation after power loss and restoration.
Retain the schematic, product information, set-up/commissioning record, test results, operating instructions and responsible contractor details.
Who can work on the system?
The gas installation and appliances require a Gas Safe registered engineer with the relevant commercial catering categories. Electrical and control work also needs appropriate competence. Because the system crosses trade boundaries, the project should identify one person or organisation responsible for overall functional coordination.
Check the gas engineer's ID card categories rather than assuming all commercial gas work is covered.
Keep the safety sequence on the installation checklist
The KIG 318 Commercial Kitchen Installation Checklist helps project teams keep interlocks, commissioning, records and handover items visible through the installation rather than discovering them immediately before opening.
Related reading
Sources and further reading
- IGEM: UP/19 Edition 2
- IGEM: UP/19 scope and application
- BSI: BS 6173:2020
- HSE: Gas safety for employers
- HSE: Gas safety in catering and hospitality
This article explains the function of an interlock; it is not a design or commissioning procedure. Gas work must be carried out by a suitably qualified Gas Safe registered engineer using current standards. Last reviewed: 13 August 2026.