Compliance · 2026
Gas Interlock Compliance in Commercial Kitchens
A gas interlock commercial kitchen system shuts off the gas to your catering appliances the moment the ventilation stops doing its job. It is not an optional extra. If you have been told you need one, or an EHO has flagged it on inspection, this is what the interlock does, when it applies, and what happens if you trade without it.
The short answer
What a gas interlock system actually does
A gas interlock ties the gas supply to your cooking line to the kitchen ventilation. Before it will release gas to the appliances, the system has to prove that the extract and make-up air fans are running and actually moving air. If the ventilation stops, slows below the proven level, or fails to start, the interlock isolates the gas at a solenoid valve and keeps it isolated until airflow is restored and the system is manually reset.
The reason is simple. Gas appliances under a canopy produce heat, combustion products and, if anything goes wrong, carbon monoxide. The ventilation is what carries all of that out of the room. Run the burners with the fans off and you are filling an occupied kitchen with the products of combustion. The interlock removes that possibility by design, rather than relying on staff to remember to switch the extraction on.
A compliant interlock comprises a handful of parts that have to work together:
Gas solenoid valve
A normally-closed valve on the gas supply that only opens when the control panel is satisfied the ventilation is running. Lose power or lose airflow and it shuts.
Airflow proving
An air pressure differential switch across the fan, a current monitor on the fan motor, or both, to prove the extract is genuinely moving air and not just powered on.
CO2 air-quality sensor
Now the minimum standard on new installations under IGEM/UP/19. It isolates the gas if carbon dioxide in the working area climbs past the set limit, catching a system that is running but under-ventilating.
Control panel and manual reset
The brain of the system. It takes the proving signals, drives the valve, and forces a deliberate manual reset after any trip — no automatic re-opening of the gas.
The rules
When commercial kitchens with gas need a gas interlock
Two documents set the expectation. BS 6173:2020, the standard for the installation of gas-fired catering appliances, states that gas appliances used with mechanical ventilation are interlocked with that ventilation. IGEM/UP/19 (Edition 2) then sets out how the interlock devices themselves apply specifically in catering. Between them, the position is settled: any commercial kitchen with gas appliances under mechanical extraction needs a gas interlock.
New kitchens
Any new commercial kitchen with gas appliances and mechanical ventilation should be fitted with a gas interlock from the outset. It has been the expected standard for new installs since BS 6173:2001, and CO2 interlocking is now part of that baseline.
Major refurbishments
A significant refurbishment of an existing kitchen brings it up to current standards. If you are reworking the cooking line or the ventilation, the interlock comes with it — this is the most common point at which an older kitchen has to catch up.
Gas plus mechanical ventilation
The trigger is the combination: gas catering appliances together with a mechanical extract system. That is the great majority of commercial kitchens. A kitchen with only electric appliances, or with no mechanical ventilation, is a different case.
After an EHO or Gas Safe flag
If an Environmental Health Officer or a Gas Safe engineer has recorded the absence of an interlock as a concern, you are already on notice. The work is no longer optional and the clock is usually running.
In practice
What a compliant installation looks like
A gas interlock is only as good as the way it is installed and commissioned. These are the details that separate a system that passes inspection from one that gets written up.
Proven airflow, not just power
The proving has to confirm the fan is moving air. A current monitor alone can be fooled by a slipping belt or a blocked filter, which is why pressure differential proving, or a combination, is the robust approach.
CO2 monitoring on new work
IGEM/UP/19 makes CO2 sensing the minimum on new installations. The gas isolates if carbon dioxide in the staff working area rises above the set limit, so an under-performing system that still proves airflow is still caught.
No overrides or bypasses
IGEM/UP/19 does not permit override switches, fan bypasses or secondary interlocking. A system wired with a way to run the gas without the ventilation is not compliant, however convenient it seems on a busy service.
Manual reset after a trip
After the interlock isolates the gas, someone has to physically reset it. The gas never re-opens on its own when airflow returns, so a fault always gets a human eyes-on before cooking resumes.
Commissioned by a competent engineer
The interlock and the gas appliances must be installed and commissioned by a Gas Safe registered engineer qualified in commercial catering. The commissioning record is what you show an EHO or your insurer.
Tied into the wider system
The interlock is one part of a properly designed extraction scheme. We handle it alongside the canopy, ductwork and make-up air on our commercial kitchen extraction work, so the proving matches the system it sits on.
Setting it straight
Common misconceptions
"A carbon monoxide alarm does the same job"
It does not. An alarm warns you after a problem exists. An interlock prevents the problem by refusing to release gas unless the ventilation is proven. The standards are built around CO2 air-quality and airflow proving, not a CO alarm on the wall.
"My kitchen is old, so it's exempt"
Age is not an exemption. An older kitchen without an interlock is exposed the moment it is refurbished, inspected or assessed after an incident. The practical answer is to retrofit, which is usually straightforward.
"We just remember to turn the fans on"
Relying on staff is exactly what the standard removes. People forget, fans fail mid-service, and filters block. The interlock is there because the consequence of getting it wrong is gas burning in an unventilated room.
"An existing interlock never needs touching"
An older interlock may pre-date the CO2 requirement, and proving switches and sensors drift over time. It should be tested as part of your gas safety regime and reviewed when the kitchen is refurbished.
The downside
What happens if you don't have one
The risk of running a gas kitchen without a compliant interlock is not theoretical. It is a safety failure with a clear regulatory and financial tail.
The immediate hazard is carbon monoxide and a build-up of combustion products in an occupied room — the scenario that has killed and hospitalised kitchen staff. On top of that sits the regulatory exposure. A Gas Safe engineer finding gas appliances on mechanical ventilation with no interlock can classify the installation as At Risk or Immediately Dangerous and disconnect it. An EHO can issue a notice or refuse to sign off a new kitchen, and serious failings under the Gas Safety (Installation and Use) Regulations carry the weight of the Health and Safety at Work Act behind them.
Then there is insurance. If a gas incident occurs in a kitchen that should have had an interlock and did not, the insurer has a clear reason to question the claim. You are left carrying the damage, the closure and the rebuild. You can read the interlock standard via IGEM, and check an engineer's commercial catering qualifications on the Gas Safe Register.
If you are not sure whether your kitchen is compliant, or you have been told you need an interlock, book a free site survey and we will tell you exactly where you stand and what bringing it up to standard involves.
Common questions
FAQ
Is a gas interlock a legal requirement?
There is no single law that says "fit a gas interlock". The requirement comes from the recognised standards, BS 6173 and IGEM/UP/19, combined with the legal duties in the Gas Safety (Installation and Use) Regulations 1998 and the Health and Safety at Work Act. In practice, a commercial kitchen using gas appliances under mechanical ventilation is expected to have an interlock, and a Gas Safe engineer, EHO or insurer will treat its absence as a serious safety failing rather than an optional upgrade.
Does every commercial kitchen need a gas interlock?
The trigger is gas catering appliances used together with a mechanical ventilation or extraction system, which covers the large majority of commercial kitchens. A kitchen with only electric appliances does not need a gas interlock, and a kitchen with no mechanical ventilation is a different and unusual case that should be assessed on its own. If you have gas under a powered canopy, you need an interlock.
Further questions
What is the difference between CO2 and carbon monoxide interlocking?
IGEM/UP/19 uses carbon dioxide (CO2) as the air-quality measure for interlocking, because rising CO2 is a reliable early sign that ventilation is not keeping up, before conditions become dangerous. Carbon monoxide (CO) is the toxic gas everyone worries about, but it appears later and is the thing the system is designed to prevent reaching the room. On new installations, CO2 sensing is the minimum, working alongside airflow proving.
Does my existing gas interlock need upgrading?
If you have a working interlock that proves airflow and isolates the gas correctly, it is not automatically obsolete. But an older system may pre-date the CO2 air-quality requirement, and the proving switches and sensors can drift over time. The interlock should be tested as part of your routine gas safety checks, and reviewed against current IGEM/UP/19 guidance whenever the kitchen is refurbished or the cooking line changes.
Who can install and commission a gas interlock?
The gas appliances and the interlock must be installed and commissioned by a Gas Safe registered engineer who holds the relevant commercial catering qualifications. On handover you should receive commissioning documentation recording that the system proves airflow, isolates the gas correctly and meets the standards. That record is what you produce for an EHO inspection or an insurer, so keep it with your gas safety paperwork.
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