NSW Plumbing Licence key terms

The network of pipes, fittings and fixtures inside a building that carries soil and waste water by gravity to the sewer connection, excluding roof stormwater and trade waste pre-treatment equipment.

The pipe that connects a single fixture's trap outlet to the main drainage line. It must be sized to carry that fixture's peak flow and graded to drain freely.

A trapped fitting installed in a drainage line to receive discharge from fixtures or surface water while maintaining a water seal that stops sewer gas entering the building.

The depth of water held in a trap that blocks sewer gases from passing into a building. It must be maintained against evaporation, siphonage and back pressure.

A one-way valve fitted to a vent pipe that admits air into the drainage system when pressure drops, protecting trap seals, while preventing sewer gas escaping into the building.

A pipe connected to the drainage system that allows air to move in and out, equalising pressure so trap seals are not siphoned or forced out by flow.

The height of the lowest inside surface of a pipe or drain at a given point, measured from a datum. It is used to set grades and confirm flow direction.

The downward slope of a drain or pipe expressed as a ratio or percentage, set so solids are carried along without the liquid flowing too fast and leaving residue behind.

A one-way device installed on a drainage line to stop sewage flowing back into a building when the downstream sewer surcharges during heavy rain or blockage.

A trapped fitting located at or near the property boundary on the discharge line, providing a seal between the private drainage system and the public sewer.

A strength and tightness test in which a gas installation is pressurised with air or inert gas and monitored for a set period to confirm there are no leaks before commissioning.

The process of finding escaping gas using approved methods such as electronic detectors or leak-detection fluid on joints, never by flame, before any installation is put into service.

The final stage of an installation where appliances are purged, ignited, adjusted and tested to confirm they operate safely and to the manufacturer's stated performance before handover to the owner.

A passage or duct that carries products of combustion from a gas appliance to outside air, designed and installed so combustion gases cannot spill back into the occupied space.

The air supplied to a gas appliance for burning fuel. It must be provided at the required rate and be free of contaminants that could affect safe combustion.

The escape of products of combustion from an appliance or flue opening into the room rather than up the flue. It indicates a drafting fault and is a serious safety hazard.

A fitting or assembly that stops water in a plumbing system flowing backwards into the supply main, protecting drinking water from contamination by pollutants or contaminants.

Any actual or potential link between a potable water supply and a source of contamination. Cross-connections must be removed or protected by an appropriate backflow device.

A valve that blends hot and cold water to deliver a controlled, safe outlet temperature, commonly used to limit scald risk at baths, basins and other outlets.

The design and adjustment of hot water delivery so stored water is hot enough to limit bacterial growth while outlet temperatures at fixtures are limited to prevent scalding.

The network of gutters, downpipes, pits and pipes that collects rainwater from roofs and surfaces and carries it to a lawful discharge point such as a street kerb or soakage system.

The vertical pipe that carries rainwater from a roof gutter or rainwater head down to the stormwater drainage system, sized to handle the roof catchment area.

A box-like fitting at the top of a downpipe that collects water from roof outlets, allows debris to settle and provides an overflow path if the downpipe blocks.

A deliberately provided outlet or gap that lets excess rainwater escape safely when a gutter or downpipe cannot cope, preventing water from entering the building.

A weatherproofing strip of metal or other material installed at junctions between roof covering and walls, penetrations or valleys to stop water entering the structure.

Any opening cut through the roof covering for a pipe, flue, vent or skylight. Each must be sealed and flashed so it remains watertight under wind-driven rain.

A pliable membrane or sheet laid under roof cladding to shed any water that passes the covering and to reduce wind and dust entry into the roof space.

A gutter formed with a flat or near-flat base and vertical sides, usually built into the roof, which requires careful sizing and overflow provision because it holds water.

The installed network of pipes, valves and outlets that delivers medical gases or vacuum from a source to points of use, and which must be installed and tested under strict controls.

The terminal fitting in a clinical area where equipment connects to a medical gas or vacuum supply. It is gas-specific and must not accept the wrong probe.

An isolation valve installed on a medical gas line to a department or zone so supply can be shut off for maintenance or emergency without affecting other areas.

The continuous flow of inert gas through a medical gas pipe during brazing that keeps oxygen away from the hot joint, preventing internal oxidation and contamination.

A controlled test of a medical gas pipeline at specified pressures using oil-free gas and approved procedures, held for a set time to prove strength and tightness.

Building systems such as heating, ventilation, air conditioning, pumps and controls that are installed and coordinated by trades alongside plumbing and drainage work.

The safe separation of equipment or a circuit from its energy source, locked and tagged where required, so work can proceed without the risk of energisation or release.

The authorisation required to perform electrical work. Plumbers may only disconnect and reconnect fixed electrical equipment within the scope their licence and training permit.

The practice of proving an electrical circuit or equipment is de-energised with a tested meter before touching it, confirming isolation has actually worked.

Equipment permanently wired to the installation, such as a hot water unit or pump, which may only be disconnected and reconnected under the restricted plumbing electrical scope.

The connection of conductive parts so they sit at the same electrical potential, reducing the risk of shock near pools, bathrooms and metallic pipework.