Gas: the law and the engineer

Lesson 1 gave you the gas law in two lines: registration binds businesses, and competence binds everyone. This lesson reads the words those two lines come from, and uses them on the cases people actually meet: a relative's favour, a favour that turns into a sideline, a card held up at the door, and an appliance you've stopped trusting. Then it looks at the US, where this course found no single rule at all.

Lesson 9, "Gas: the smell and the valve", gave each country's leak steps, and lesson 7, "Heating: boilers, radiators and furnaces", drew the line at the boiler's casing. Most of this lesson's sections state law, so here is the caution that goes with them. This is general information, not legal advice. The rules differ between England, Wales, Scotland and Northern Ireland, and between US states and cities, and they change.

The law in Great Britain and Northern Ireland

This is general information, not legal advice.

Two duties in one regulation

Regulation 3 of the Gas Safety (Installation and Use) Regulations 1998 applies in England, Wales and Scotland. Its first paragraph: "No person shall carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so."¹ "No person" means anyone.

Its third paragraph is the one people mean when they talk about the Register. In plain words: an employer can't let staff do gas work, and a self-employed person can't do it, unless they belong to the class of people HSE has approved. The paragraph itself reads: "no employer shall allow any of his employees to carry out any work in relation to a gas fitting or service pipework and no self-employed person shall carry out any such work, unless the employer or self-employed person, as the case may be, is a member of a class of persons approved for the time being by the Health and Safety Executive".¹ HSE's page on the Register says a gas business must be on the Gas Safe Register.⁹ Read who the paragraph names: employers and the self-employed. A householder working on their own home is neither.

Three kinds of text are in play from here on. The Regulations are the law. HSE's Approved Code of Practice sits inside L56, HSE's book on the Regulations, and has a special legal status, below. The rest of L56 is HSE's guidance, which explains both. The guidance says, in paragraph 52: "For the purposes of GSIUR, ‘work’ includes do-it-yourself activities, work undertaken as a favour for friends and relatives, and work for which there is no expectation of reward or gain, eg voluntary activity for charities. This means that anyone carrying out such work must have the necessary competence, as required by regulation 3(1). However, membership of an HSE-approved class of persons (under regulation 3(3)) is required only by businesses carrying out gas-fitting work."⁴ (GSIUR is L56's short name for the 1998 Regulations.)

So there are two duties. Registration binds those who do gas work as a business. Competence binds everyone, householders included.

What "competent" means

The Code isn't the Regulations, but it isn't only advice either. L56 says: "You may use alternative methods to those set out in the Code in order to comply with the law." But the Code "has a special legal status. If you are prosecuted for breach of health and safety law, and it is proved that you did not follow the relevant provisions of the Code, you will need to show that you have complied with the law in some other way or a Court will find you at fault."⁴ So there are other ways to comply, but someone who didn't follow the Code has to prove theirs.

Paragraph 81 is part of the Code, and it says: "Gas work should only be undertaken: (a) by a person who has successfully completed an industry-recognised training course followed by assessment of competence." Its other two limbs are for people who are or were registered and have proved competence through a certification scheme, and for premises outside the Regulations.⁴ Paragraph 85, which is guidance, defines the word: "Competence is a combination of practical skill, training, knowledge and experience to carry out the job in hand safely, and ensuring the installation is left in a safe condition for use."⁴

And paragraph 83 applies the duty to everyone: "do-it-yourself gas engineers and those performing favours for friends and relatives all need to have the required competence." It adds that the competence needed "should match the full extent of work done, but needs only to be sufficient for and relevant to that work".⁴ For gas work beyond the user instructions, the Code's measure is still the course and the assessment in paragraph 81.

Regulation 3 makes two narrow exceptions, from the registration duty only and not from competence: replacing the hose or the regulator fitted to a portable or mobile space heater, and replacing a hose that connects a refillable cylinder to the pipework.¹ HSE's guidance says the same: people doing those like-for-like replacements "need to have the required competence and ensure that they follow instructions, eg given by the gas supplier/appliance manufacturer, as appropriate."⁴

So, under the gas safety regulations, "it's illegal to do any gas work yourself" overstates the law, because the registration duty doesn't reach a householder, and "it's legal, so it's fine" misleads, because the competence duty does, measured by a recognised course and an assessment. Other law can apply as well. In England and Wales, the Building Regulations 2010 list installing a heat-producing gas appliance, such as a boiler, among the jobs a member of the Gas Safe class can self-certify; lesson 22 comes back to that.

One rule that binds you in a leak

Regulation 6(5) is a single line: "No person searching for an escape of gas shall use any source of ignition."² L56 says this prohibition "extends to householders and other members of the general public."⁴ So in Great Britain, part of lesson 9's no-flame step is law as well as advice: nobody looking for a leak may use a flame or any other source of ignition. A lighter held to a pipe to find a leak is what it forbids.

What the advice says

The advice is the one lesson 1 gave, and it hasn't moved. HSE "strongly advises that all gas appliances, flues and pipework should be installed, regularly maintained and serviced at least annually by a Gas Safe registered engineer", and the Register says "Don’t DIY with gas appliances, always use a Gas Safe registered engineer".⁵⁶ So gas work in Great Britain is Call someone.

Northern Ireland

Northern Ireland has its own instrument, the Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004. Its regulation 3 has the same shape: "A person shall not carry out any work in relation to a gas fitting or gas storage vessel unless he is competent to do so", and the same registration duty on employers and the self-employed, with the approval given by "the Executive" rather than by HSE.⁸ HSE says the Gas Safe Register covers "Great Britain, Northern Ireland, the Isle of Man and Guernsey".⁹ L56 is written for the 1998 Regulations, and this course did not read the Northern Ireland guidance.

A free hob from a brother-in-law

This is general information, not legal advice.

Now the harder case, in England. Sam lives in a 1970s townhouse in Rutland and has bought a new gas hob. His brother-in-law, who is handy, has fitted kitchens and is not registered, offers to put it in on Saturday for nothing. Sam wants to know where he stands. Read it with him, a step at a time.

Is it gas work? Yes. Fitting an appliance is installation, and L56 says installing a gas appliance counts as work "even where the connection is made by a bayonet fitting or other self-sealing connector".⁴ Paragraph 52 says a favour for a relative is work.

Does the registration duty reach the brother-in-law? Regulation 3(3) names employers and the self-employed, and paragraph 52 says membership "is required only by businesses carrying out gas-fitting work". An unpaid favour isn't a business, so on those words, no.¹⁴

What about having it checked afterwards? The brother-in-law suggests a registered engineer could look it over when he's done. The Gas Safe Register says of this: "It is illegal for someone who is not Gas Safe registered to fit a gas appliance or do other gas work and then have the work checked by a Gas Safe registered engineer. Both parties would be breaking the law."⁶ That is the Register's statement. If the first person does gas work as a business, regulation 3(3) covers them. For an unpaid helper who does have the competence, this course read regulation 3 and HSE's guidance and couldn't find the provision the Register has in mind, so it reports the sentence as Gas Safe's, not as the law. Either way, a check afterwards doesn't supply the competence the law asks of the person doing the work.

And the advice? HSE and the Register both say to use a Gas Safe registered engineer.⁵⁶ The Register adds that using an illegal gas worker "could invalidate the warranty on your boiler and may invalidate your home insurance".⁷ What home insurance does and does not cover is Personal Finance Fundamentals lesson 8, "Handing off what you cannot absorb".

So Sam's hob is Call someone: the law asks for a competence neither of them has, and the advice is a registered engineer.

What you may do yourself

This is general information, not legal advice.

If gas work is for an engineer, what is left for you? The Register answers on the same archived page. You "can perform the tasks set out in the user’s instructions, (provided by the appliance manufacturer) that are intended for the user to carry out. This would not be a breach of the law." And: "The law allows you to replace or adjust any component or control that is designed to be operated or replaced by the consumer e.g., a cooker tap control knob." It then draws the line: do nothing that disturbs the gas-carrying parts, such as the supply pipe, or that could affect combustion.⁶

The same page deals with the case on an appliance. A decorative case, it says, can usually be removed by the consumer, such as ones that "can be lifted off or are hinged panels and do not need to be unscrewed". But many cases also form part of the combustion circuit, and "If removing the case involves undoing a number of screws, this normally means it is a functional case and it should not be removed by the consumer".⁶ In doubt, it sends you to the maker's instructions, helpline or website.

HSE, in its guidance for landlords, gives one everyday case. A free-standing cooker connected by a flexible connector (a bayonet fitting) can be moved temporarily, for instance to clean the space it stands in, and that is not "work" under the Regulations. Anything more is, and HSE says it "must be carried out by a Gas Safe registered engineer". For a householder working on their own home that is advice, since the legal duty there is the competence one above.¹⁰ The Register's own advice is stricter: "never try to fix, fit or move appliances like your boiler or cooker yourself".⁶ So even the temporary move is Yours, on conditions: the cooker's user instructions allow it and you don't disturb the connection. Otherwise, Call someone.

Two more lines from the Register belong on your list. Know where your gas pipes run, so that you "don’t accidentally hit them during DIY work", and don't block or cover air vents and flues.⁶ And some work inside a boiler's casing doesn't need a Gas Safe engineer at all: the Register says a non-gas part such as a water circulating pump or a central heating control valve can be replaced by another competent tradesperson, a plumber or an electrician, provided nobody breaks a combustion chamber seal or disturbs a gas-carrying part or the module that controls combustion.⁶ That's a trade's job, not yours; it's here because a plumber may be the right person for some boiler faults.

So the user tasks are Yours, on conditions, and the condition is that the appliance's own user instructions give the job to the user.

Checking the engineer

A Gas Safe registered engineer carries an ID card. HSE describes it: "The front of the card has a photograph, a registration number and an expiry date and the reverse shows the different categories of work that the engineer is qualified to undertake, eg cookers, boilers, gas fires."⁹

The back is the part people skip. Registration is not a licence for every gas job: the card lists what this engineer is qualified for, and HSE's home-owner page says "The gas engineer's competencies are clearly marked on the back of the engineer's Gas Safe Register ID card."⁵

To check that the person at your door is the engineer on the Register, HSE's page for home owners sends you to the Register's Check an Engineer service on its website. You enter "the licence number from the engineers ID card", and it shows pictures of registered engineers and their qualifications.⁵ HSE's page on the card calls the number on its front a registration number, and this course didn't see a card, so if you can't tell which number is the licence number, ring the Register. HSE gives its freephone helpline as 0800 408 5500, and says the helpline can also send the engineer's picture to a mobile phone as a picture message.⁵ For a question about gas safety rather than about one engineer, HSE runs a free Gas Safety Advice Line on 0800 300 363, open 9.00am to 5.30pm Monday to Thursday and 9.00am to 5.00pm on Friday, bank holidays excepted.⁵

Here is the check done once, in the simple case. Priya lives in a semi outside Chelmsford, and her combi boiler is being replaced. The engineer arrives and she asks for his card, as the Register's page says to.⁶ On the front: his photograph, which matches him, a registration number, and an expiry date next spring. On the back, among the categories, is one for boilers. She types the licence number into Check an Engineer on the Register's website, and the name, photograph and qualifications match the card.⁵ The job is in his categories, the card is in date and the Register agrees, so she lets him start. Had the back listed only cookers and fires, she would have asked for an engineer whose card covers boilers.

The reason to bother is the Register's own figure: "Approximately two thirds of illegal gas work inspected by the Register has been found to be unsafe."⁷ That is the Register's figure for the work it inspected, with no year or count given on the page; it describes work that reached an inspection, not all unregistered work. How to check a trader more generally, and what to agree before work starts, is lesson 23, "Hiring a tradesperson, and when to stop". The doorstep pressure pattern is Personal Safety lesson 5, "Home, the door and the doorstep".

An appliance you don't trust, and the annual service

This is general information, not legal advice.

HSE is plain about the first: "It is illegal for anyone to use a gas appliance if they suspect it is unsafe. Turn the appliance off and do not touch it until it has been checked by a Gas Safe registered engineer."⁵ The regulation behind it, regulation 34, puts the duty on "the responsible person", which it defines as the occupier, the owner and anyone with authority to act on the gas fittings there, so it covers most readers of this course.¹⁶

The signs that should make you suspect one are set out differently in each country. In Great Britain, HSE's warning signs at the appliance are lesson 11's, with carbon monoxide. In the US, Columbia Gas of Ohio, about its own customers, tells them to contact "a qualified professional" if they notice a change such as no heat or overheating from a furnace or boiler, a yellow flame or soot around a burner on a gas stove, or a furnace or water heater fan that keeps kicking on and off.¹¹

The annual service is HSE's advice, quoted above: installed, maintained and "serviced at least annually by a Gas Safe registered engineer".⁵ HSE's reason is on the same page: "Every year around 7 people die from gas-related carbon monoxide (CO) poisoning." The page gives no year for the figure.⁵ HSE also says a carbon monoxide alarm "should not be regarded as a replacement for regular maintenance".⁵ Lesson 11, "Carbon monoxide and the alarms that warn you", sets out that order in full.

If you rent in Great Britain, the law puts the check on your landlord. Regulation 36 requires a landlord to have each gas appliance and flue they provide "checked for safety within 12 months of being installed and at intervals of not more than 12 months since it was last checked", to keep a record, and to give a copy to each existing tenant "within 28 days of the date of the check".³ (Where no gas appliance is in any room the tenant occupies, the landlord may display the record instead.) The duty covers homes let on a lease of less than seven years or a periodic tenancy, and homes or rooms let under a licence. HSE's domestic gas FAQs, in the section for tenants, include a specimen letter asking to see the record.¹⁰ That is the whole of the landlord law this course teaches; the rest of tenancy law is not taught here.

Who may work on gas in the US

This is general information, not legal advice.

This course read no general US rule on who may do gas work. What it read is one utility's advice and two places' law.

The advice: Columbia Gas of Ohio says "For your safety, a qualified professional should perform all work on natural gas lines and equipment inside the home", and of fitting an appliance, "Never attempt this yourself!"¹¹ It says "qualified", not "licensed".

New York City: the city's Department of Buildings says that ordinary repair work needing no permit, including "allowable replacement/relocation of plumbing, gas piping, equipment and components", still "must be performed by a Licensed Master Plumber."¹² No permit is not the same as no licence.

Texas: the state's plumbing licence law says "A property owner is not required to be licensed under this chapter to perform plumbing in the property owner's homestead" (homestead is the statute's word, and this course didn't read where Texas law defines it). It defines "plumbing" to include piping used to "supply, distribute, circulate, or recirculate water, other liquid, or gas".¹³ So the state licence law does not require a homestead owner to be a licensed plumber for gas piping. That is a statement about the licensing statute, read in the state board's unofficial 2023 text. The exemption says nothing about permits and inspections, which are set locally, and this course did not read any Texas city's rules.

The Texas exemption is another case of the law allowing more than the advice read, which is a utility's "qualified professional". Wherever you are in the US, ask your city or county building department what a permit needs, and your gas utility what it advises, before anyone touches a gas line. On the advice read, the label is Call someone.

What people get wrong

"It's illegal to do any gas work yourself." Not in those words. In Great Britain the registration duty binds businesses, and the competence duty binds everyone (see "The law in Great Britain and Northern Ireland" above).

"It's legal for me to do it, so it's fine." The competence duty is law too; see what "competent" means, above. HSE and the Register both advise a registered engineer.

"If a registered engineer checks it afterwards, it's all right." The Register says that arrangement puts both parties in breach (a statement this course couldn't match to a provision for a competent unpaid helper; see "A free hob from a brother-in-law"). Either way, a check afterwards does not make the first person competent.⁶

"A Gas Safe card means the engineer can do any gas job." The back lists the categories they are qualified for (HSE).⁹

"Texas lets homeowners do their own gas work, so America does." Texas's exemption is from one state's licence law, and says nothing about permits there or about any other state (see "Who may work on gas in the US" above).¹³

Practice

For your plan

This lesson adds to the calendar: every gas appliance serviced once a year by a Gas Safe registered engineer (HSE), or by a qualified professional in the US; and, if you rent in Great Britain, the landlord's check record within 28 days of each check. It adds to the call list: how to check an engineer on the Register's site, the Register's helpline, and HSE's Gas Safety Advice Line. It adds to the stop list: any gas job beyond the user instructions, any case held on with screws, and any appliance you suspect is unsafe, which is turned off and not used until an engineer has checked it.

Connections

Lesson 1, "How a house works, and where it switches off", gave the gas law in brief, and this lesson read it in full; lesson 7's line at the boiler's casing comes from the same rules. Lesson 9, "Gas: the smell and the valve", gave the leak steps, and regulation 6(5) makes part of one of them law. Next, lesson 11, "Carbon monoxide and the alarms that warn you", takes what a badly burning appliance gives off, and why the alarm is the last protection, not the first. Lesson 22, "Who may do what: reserved work, and the argument about licensing", comes back to who may do gas and electrical work across the UK nations and five US places, including the Building Regulations, and lesson 23 to checking a trader.

Go deeper

• HSE, "Gas safety: home owners", free. The regulator's short answers on leaks, servicing, alarms and checking an engineer.
• HSE, Safety in the installation and use of gas systems and appliances, L56, fifth edition, 2018, a free PDF. This course read paragraphs 52 to 55 and 81 to 95, the Code's legal status and paragraph 121. Paragraphs 52 and 81 to 85 are the two duties in HSE's own words.
• Gas Safe Register, "Don't DIY when it comes to gas appliances", as archived on 23 October 2025, free. What the Register says you may do and may not, including the two kinds of casing.

Sources

1. The Gas Safety (Installation and Use) Regulations 1998 (SI 1998/2451), regulation 3. Read: in full; re-read on the live page 26 September 2026, no known outstanding effects. Extends to England, Wales and Scotland.
2. The Gas Safety (Installation and Use) Regulations 1998, regulation 6. Read: in full on the live page, 25 September 2026.
3. The Gas Safety (Installation and Use) Regulations 1998, regulation 36. Read: in full, including the definitions and paragraphs (3) to (7), on the live page, 26 September 2026.
4. Health and Safety Executive, Safety in the installation and use of gas systems and appliances, L56, fifth edition, 2018. Read: the legal-status page; paragraphs 52 to 55, 81 to 95 and 121; the glossary entry "gas engineer"; re-read 26 September 2026.
5. Health and Safety Executive, "Gas safety: home owners". Read: full text; re-read 26 September 2026, including the Register's helpline number.
6. Gas Safe Register, "Don't DIY when it comes to gas appliances", Internet Archive capture 20251023004454 (the live site blocks automated readers). Read: full page text of the capture, re-read 26 September 2026.
7. Gas Safe Register, "Concerns & Reporting Illegal Gas Work", Internet Archive capture 20260221055602. Read: full page text of the capture, 25 September 2026.
8. The Gas Safety (Installation and Use) Regulations (Northern Ireland) 2004 (SR 2004/63), regulation 3. Read: full text of regulation 3; re-read on the live page 25 September 2026, no known outstanding effects.
9. Health and Safety Executive, "Gas Safe Register". Read: full text; re-read 26 September 2026.
10. Health and Safety Executive, "Domestic gas: frequently asked questions". Read: the landlord and tenant sections; re-read 26 September 2026. The bayonet-cooker lines are in the section for landlords.
11. Columbia Gas of Ohio, "Safe appliance installation". Read: full page; re-read 25 September 2026. An Ohio utility, about its own customers.
12. New York City Department of Buildings, "Project Requirements for Owner: Residential and Community Facilities". Read: full page; re-read 25 September 2026. Undated.
13. Texas State Board of Plumbing Examiners, Plumbing License Law, unofficial plain-view text, June 2023, Texas Occupations Code chapter 1301. Read: sections 1301.002(7), 1301.051 and 1301.052; re-read 25 September 2026. The official statutes site returns a page that needs a script to display, so the board's unofficial text is the one read.
14. Health and Safety at Work etc. Act 1974, section 53. Read: the definition of "self-employed person", on the live page, 26 September 2026; and the 1998 Regulations' introduction, which names section 15 of this Act among the powers they were made under.
15. Interpretation Act 1978, section 11. Read: in full on the live page, 26 September 2026, no known outstanding effects.
16. The Gas Safety (Installation and Use) Regulations 1998, regulation 34. Read: paragraphs (1) and (2), on the live page, 26 September 2026, no known outstanding effects.