Hiring an unregistered gas engineer is one of the most dangerous mistakes a London homeowner can make. It's also illegal. Every year, people are seriously injured or killed by gas work carried out by unqualified tradespeople. This guide explains exactly what to look for — and what to avoid.
What Is Gas Safe Registration?
Gas Safe Register is the official UK register of gas engineers who are legally qualified to work on gas appliances. It replaced CORGI in 2009 and is regulated by the Health and Safety Executive (HSE).
Under the Gas Safety (Installation and Use) Regulations 1998, it is a criminal offence for anyone who is not Gas Safe registered to carry out work on gas fittings and appliances. This applies to:
- Boiler installation, repair, and servicing
- Gas fire installation and maintenance
- Gas hob, oven, and appliance connections
- Any work on the gas supply pipe or meter
Who Does NOT Need Gas Safe Registration?
Not all plumbing work involves gas. A standard plumber (without Gas Safe registration) can legally carry out:
- All water supply and drainage work
- Tap, toilet, and shower repairs
- Radiator installation (if not connected to a gas boiler)
- General bathroom and kitchen plumbing
However, if any work involves connecting to or working near gas pipes or appliances, Gas Safe registration is required.
How to Verify a Gas Safe Engineer in London
There are two ways to verify Gas Safe registration:
- Ask to see their Gas Safe ID card before work begins. Every registered engineer carries a card showing their name, photo, registration number, and the specific type of gas work they are licensed to carry out. Check the expiry date.
- Check online at gassaferegister.co.uk — enter their licence number and the website will confirm whether they are registered and what categories of work they are authorised for.
Important: The ID card lists specific categories of work. An engineer registered for domestic natural gas boilers is not automatically authorised for LPG appliances, for example. Always check the card matches the work you need.
Questions to Ask Before Hiring a Gas Safe Plumber
- "Can I see your Gas Safe ID card?" — any legitimate engineer will show this immediately
- "What categories of gas work are you registered for?" — match this to your job
- "Will you provide a Gas Safe certificate after the work?" — legally required for new installations and major repairs
- "Are you VAT registered?" — relevant for budgeting larger jobs
- "Do you carry public liability insurance?" — protects you if they cause damage
- "Can you provide a written quote before starting?" — never agree to gas work without a written estimate
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Be wary of any gas engineer who:
- Refuses to show their Gas Safe ID card — this is an immediate disqualifier
- Offers unusually low prices for boiler work — unregistered engineers undercut the market because they have no certification costs
- Says you don't need a certificate — for new boiler installations and certain repairs, a Gas Safe certificate is legally required
- Works in cash only with no paperwork — this makes it impossible to trace them if something goes wrong
- Is unwilling to let you check their registration online — a legitimate engineer has nothing to hide
- Recommends unnecessary work — get a second opinion if you're not sure
What Can Go Wrong With Unregistered Gas Work?
The consequences of using an unregistered gas engineer can be severe:
- Gas leaks — improper connections can cause slow or sudden gas leaks, creating an explosion risk
- Carbon monoxide poisoning — CO is odourless and colourless; faulty boiler work is a leading cause of CO deaths in the UK
- Voided home insurance — if your insurer discovers gas work was carried out by an unregistered engineer, your policy may be invalid
- Legal liability — as the homeowner, you may be liable if you knowingly allowed unregistered gas work on your property
- Failed property sale — buyers' solicitors now routinely request Gas Safe certificates; missing documentation can delay or kill a sale
How Emergency Plumbers Vets Gas Engineers
Every plumber on our London network who carries out gas work has their Gas Safe registration verified before they are accepted. We check:
- Current Gas Safe registration status
- The specific work categories they are authorised for
- Public liability insurance (minimum £1m)
- Identity verification
We re-verify registrations annually and remove any engineer whose registration lapses or is suspended.
Frequently Asked Questions
How much extra does Gas Safe registration add to the cost?
Gas Safe work commands a small premium — typically £80–£120/hr compared to £60–£100/hr for non-gas plumbing. The premium reflects the engineer's additional certification costs and the specialist nature of the work. See our full London plumber costs guide.
Do I need a Gas Safe certificate for a boiler service?
A standard annual boiler service does not always require a certificate — but many engineers provide one as proof of the service. A new boiler installation legally requires a Building Regulations Completion Certificate (which the installer submits to your local council) and a commissioning certificate. Always ask your engineer what documentation they will provide.
What is a Landlord Gas Safety Certificate?
If you are renting out a property in London, you are legally required to have all gas appliances inspected and certified by a Gas Safe registered engineer every 12 months. This is called a Landlord Gas Safety Certificate (CP12). Failure to comply is a criminal offence and can result in a £6,000 fine per appliance.