Slab penetration with a late-discovered gas line
You are the licensed plumber on a renovation of a 1970s brick-veneer house. The client wants a new bathroom, and the drain for the new shower must cross a 200 mm suspended concrete slab to reach the existing stack. You set out the penetration and core a 100 mm hole. While drilling, the bit snags and you smell gas. The gas line to the kitchen cooktop is a 15 mm copper run that, according to the owner, was installed by the previous owner about 15 years ago and has no documentation. The gas meter is at the front of the house; the cooktop is at the rear. The slab is the ceiling of a habitable basement room below. The client is impatient and asks you to just patch the pipe and keep going.
1. What should you do immediately after the snag, and how do you decide whether the gas installation is compliant before any repair?
Read the worked answer
Stop work and make the area safe first. Do not continue coring. Isolate the gas supply at the meter, ventilate the basement, and keep ignition sources away. Notify the occupant and, if gas is escaping uncontrollably, contact the gas distributor and emergency services.
The key judgement is that a struck gas line is not a patch-and-move-on situation. The pipe is concealed in a slab with no documentation, so you cannot assume its route, material, or condition. Before any repair you must establish the installation's status: locate and expose the run, confirm it is copper and not deteriorated, and check that it is not buried in concrete without protection. Gas pipes must not be encased in concrete in a way that prevents inspection or access, and any concealed run needs to be identifiable and protected. A 15 mm line feeding a cooktop over a long run also needs a pressure and sizing check, because the previous owner's work may never have been verified.
If the run is non-compliant or cannot be verified, the correct answer is to reroute it in a compliant accessible path and have the work certified, not to patch the damaged section and conceal it again. Document the find and advise the client in writing.
2. The client insists on patching and continuing. How do you respond, and what records do you leave?
Read the worked answer
You cannot comply. As the licensed person you are responsible for the gas installation you touch, and concealing a damaged, undocumented line in a slab would leave a defect you created or failed to rectify. Explain plainly that the repair must be done compliantly and that continuing the drain work over a live, unverified gas line is unsafe.
Offer a practical path: isolate and cap the line, reroute it externally or in an accessible ceiling space, pressure-test it, and issue a compliance certificate for the altered installation. Only then proceed with the shower drain. If the client refuses, record your advice in writing, note the isolation, and do not reconnect or conceal anything.
Leave records: a written notice describing the defect, the date and time, the isolation performed, photographs of the exposed pipe, and a copy of the compliance certificate for the rerouted work. These records protect both safety and your licence if the matter is later disputed.