AS/NZS 5112:2015 pdf – Tunnel type terminal neutral bars for low voltage switchboards- Requirements for termination of copper conductors up to 50 mm.
Compliance shall be established in accordance with Clause 7.6.1.
6.5.2 Tunnel entries
The entry into each tunnel shall be clean and free from all burring to prevent mechanical damage to conductor strands.
Compliance shall be established in accordance with Clause 7.6.2.
6.5.3 Diameter of single screws in direct contact with a conductor
A single screw which is in direct contact with a conductor shall have a nominal diameter of at least 80% of the tunnel diameter.
If two screws are supplied the nominal diameter as a percentage of the tunnel diameter is not specified.
Refer to Appendix B for guidance.
Compliance for single screws shall be established in accordance with Clause 7.6.3.
6.5.4 Screws for tunnel terminals and saddle ter,ninals
6.5.4. 1 Number and spacing of screws in direct contact with a conductor
If screws are in direct contact with a conductor, two screws shall be used for the following:
(a) The main incoming neutral, sub main neutral or connections joining one bar to another.
(b) The main earthing conductor (minimum size 4 mm2).
(c) The neutral bar to earth bar or main earth connection (MEN connection).
(d) A PEN (protective earth neutral). e.g. to an outbuilding.
Exception: One screw with a nominal diameter of at least 80% of the tunnel diameter.
The screws shall be spaced far enough apart and the bar sufficiently wide enough to enable access to the screw heads by normal hand tools to allow screws to be tightened to the torques values in Table 2.
Grub screws shall have sufficient length to ensure effective thread purchase and not fall into the tunnel when no conductor is present, e.g. 8.5 mm diameter tunnel, M8 grub screw x 10.2 mm long.
Compliance shall he established in accordance with Clause 7.6.4
6.5.4.2. 1 Tunnel terminals with a plate or ferrule giving indirect pressure
Tunnel terminals with a plate or ferrule giving indirect pressure may have one screw for the connections specified in Clause 6.5.4.1.
6.5.4.2.2 Saddle term inals
The saddle of a saddle terminal shall be positioned to clamp the conductor across the full
diameter of the conductor by a screw on each side of the conductor position. Compliance shall be established in accordance with Clause 7.6.4.2.
6.6 4lechanical characteristics of screws and bars
6.6.1 General
When screws are tested in accordance with Clause 7.7.1, there shall be no undue damage to the screws or bars and the screw length will ensure the screw reaches the bottom of the tunnel.
AS/NZS 5112:2015 pdf – Tunnel type terminal neutral bars for low voltage switchboards- Requirements for termination of copper conductors up to 50 mm
