Before a project starts, determine the responsibility for specific work between the plumber, the main contractor and the electrician.

Discuss the location of pipe runs with the main contractor to minimise cutting or notching of framing.

Find out about:

• general installation requirements
• location
• access for maintenance and replacement
• provision of isolating valves
• equipotential bonding
• pipe insulation.

General installation requirements

Pipework must:

• comply with the durability requirements of B2 Durability
• be compatible with the support
• be installed to allow for thermal movement
• be protected from freezing by insulation, or being buried below the level of freezing
• be protected from damage
• be wrapped in flexible material or sleeved when penetrating masonry or concrete.

Location

Pipework may be installed:

• in a roof space
• under a timber floor
• below a concrete slab (BRANZ does not recommend within slab installation).

Where pipes are buried, they must have:

• 600 mm cover under trafficked areas
• 450 mm cover under lawns and garden areas (non-trafficked)

Where pipes are under concrete, they must have 50 year durability.

Where pipes cross other services below ground, they must comply with the details shown in the following diagram.

Access for maintenance and replacement

Pipes installed in locations that are difficult to access should:

• have a detailed durability statement for 50 year service from the manufacturer
• if passing through a structural element, be sleeved in a larger pipe that is open at both ends to allow the pipe to be inspected or replaced if necessary
• be installed in a chase or duct which will provide ready access and will not compromise structural elements.

Provision of isolating valves

Isolating valves are required to be installed in accessible positions points in the supply system to allow maintenance and repairs to be carried out. They must be provided in accordance with AS/NZS 3500.1 and NZBC G12/AS1 as shown below:

Location	AS/NZS 3500.1	NZBC G12/AS1
At the boundary	Yes	Yes
Inlet to a storage tank (cold or hot)	Yes	Yes
Outlet to storage tank (over 50 litres)	Yes	2
Inlet to a flushing cistern	Yes	2
Each appliance	Yes	2
Each backflow prevention device	Yes	Yes
Each thermostatic mixing valve	Yes	2
Each pressure limiting device	Yes	2
At each branch serving a separate dwelling	Yes	Yes

Equipotential bonding

Electric shock from water pipes may occur in any building where:

• the water supply piping is metal and in contact with the ground
• an electrical supply is provided into the building
• building occupants are able to make contact with exposed pipes.

To avoid the potential of electric shock:

• the pipework must be connected to an earth electrode using earth-bonding conductors
• metallic fixtures must be bonded to the pipework.

Safety precautions must be followed when cutting metal pipes.

Pipe insulation

NZBC Acceptable Solution G12/AS1 requires pipework to be insulated to:

• limit heat loss (hot water pipes)
• prevent water in pipes from freezing (hot and cold water pipes).

BRANZ recommends that all water pipes are insulated except where connected to a heat dissipation device.

More information

•    Energy>Water heating>Water heating supply and pipework