Your gas engineer finishes up, wipes their hands, and slides a small card across to you. You glance at it. There's a logo, some numbers, a couple of letter codes you don't recognise. You say thanks, maybe offer a cup of tea, and the card ends up on the kitchen counter next to the takeaway menus. Gone by Tuesday.
That card is a legal document. Not in a vague, technically-speaking sort of way. In an actual, courts-would-care-about-this sort of way. And buried in those two-letter codes is a formal verdict on whether your home is, right now, safe to be in.
Worth knowing what it says, then.
The Three Verdicts (Not the Three Suggestions)
Every Gas Safe registered engineer in the UK is required by law to classify any gas appliance they inspect. There are three possible outcomes. They are not opinions. They are formal safety classifications with specific legal consequences attached to each one.
The first is ID: Immediately Dangerous. This means the appliance poses an immediate risk to life. Carbon monoxide leaking into the room. A flue so badly deteriorated that combustion gases are backing up inside the house – something that cannot be left running. Under the Gas Safe Register's own procedure – which engineers are legally bound to follow – an ID classification requires the engineer to ask your permission to disconnect the appliance on the spot. If you refuse permission, they are required to warn you in writing that you are living with something dangerous and to notify your gas supplier, who can then act without your consent. That is not a letter from a worried friend. That is a statutory notification.
The second verdict is AR: At Risk. The appliance isn't going to hurt you in the next ten minutes, but there's a fault, a deterioration, or a setup that puts you in danger if it's left unattended. An AR classification doesn't require immediate disconnection, but the engineer must tell you in writing what the risk is, advise you not to use the appliance, and again notify your supplier if you carry on regardless. The word "advise" sounds soft. The legal position once that card is in your hand is less so. If something then goes wrong and it comes out that you were handed an AR card and carried on using the boiler, your insurer's position becomes considerably more comfortable than yours.
The third is NCS: Not to Current Standards. This one trips people up because it sounds relatively harmless – a bit out of date, perhaps, like a kitchen from 2003. It doesn't mean dangerous today. It means the appliance or its installation no longer meets the standards that would be required if it were being installed fresh. Worth fixing, worth budgeting for, worth not ignoring indefinitely. But it's not a crisis. For plumbing and heating services, visit https://perkypad.co.uk/buying-tips/the-furniture-in-your-living-room-has-already-survived-a-fire-test/
What Your Signature Actually Means
Here's the part most people miss entirely. When you sign the Gas Safe Register record – and many engineers will ask you to sign or at least acknowledge the paperwork – you are confirming that the classification was explained to you and that you received it. At that point, the legal responsibility shifts. The engineer has done their job. You are now the person who knows.
This matters enormously for AR and ID classifications. If you carry on using an appliance marked Immediately Dangerous, you have been warned formally, in writing, by a qualified professional acting under statutory obligation. Whatever happens next, you were told. That's not a moral judgement, just the legal reality of what the card represents.
How to Actually Read the Thing
Most Gas Safe cards list each appliance inspected, its classification, and a space for the engineer's notes. If everything is fine, you'll see nothing alarming – possibly a tick, possibly the word "Safe" or no code at all. But scan down to the classification column before you put it away. If you see ID, AR, or NCS against anything, that's your cue to ask questions before the van pulls out of the drive. Not three weeks later when you can't remember the engineer's name.
Keep the card somewhere sensible too. Not the takeaway drawer. If you rent the property out, you're legally required to hold a copy and provide it to tenants.
It's a small bit of card. It carries a surprising amount of weight.
FAQ
What do ID, AR and NCS mean on a Gas Safe card?
When an engineer carries out a gas safety inspection of an appliance, he will classify it as ID (Immediately Dangerous), AR (At Risk) or NCS (Not to Current Standards). These are formal safety classifications that all Gas Safe registered engineers must use when inspecting appliances, each with its own legal consequences. ID and AR classifications relate to danger. NCS installations are not dangerous but are not operating to current standards.
What happens if my engineer marks an appliance as Immediately Dangerous?
If the engineer wants to disconnect your appliance immediately, s/he must ask for your consent to do so. If you refuse, the engineer must provide you with written notification of the danger posed by the appliance and notify your gas supplier, who can then act without your consent. Appliances classified as ID pose an immediate risk to life, and must not be left connected and switched on.
Can I keep using a boiler marked At Risk?
We advise against using it, and require that the engineer sets out the risk in writing. You don’t have to disconnect it immediately but your supplier can be notified that you are intentionally ignoring the warning. Subsequent failure may result in your insurer’s having a significantly stronger position than yours, since you had been formally warned of the risk by a qualified professional.
What does signing the Gas Safe record actually mean?
Your signature on the document confirms that the classification has been explained and that a copy has been given to you. Thereafter you shall be legally responsible, as the engineer has done their job, and for ID and AR classifications this means you have been provided with a formal written warning by a qualified professional.
