AS NZS 5112:2015 – Tunnel type terminal neutral bars for lowvoltage switchboards-—Requirementsfor termination of copper conductors upto 50 mm2
AS NZS 5112:2015 – Tunnel type terminal neutral bars for lowvoltage switchboards-—Requirementsfor termination of copper conductors upto 50 mm2.
The bars shall be provided with clamping facilities for sccurely terminating the conductors used in normal service.
The clamping of conductors shall be secure, not loosen in normal service and not exceed ihe allowable temperatures.
6.2 Range of conductors and connection requirements
6.2.1 Range of conduciors to he connected
The bars shall bc prosided with means to clamp stranded, solid and Ilexible copper conductor as shown in Table I. The conductors shall be unprepared and prepared conductors in accordance with the manulaciurer’s instructions.
The maximum size of an unprepared conductor to be clamped shall bc at least one size larger than the conductor with a current rating in Table 4 corresponding to the rated current of the neutral bar.
Compliance shall be established in accordance with Clauses 184.108.40.206 and 220.127.116.11.
NOTE: The test of 7.10 is carried out on the cable size corresponding to the rated current in Table 4, e.g. A 2$OA test is carried out on a 35 mm2 in Table 4. and not on the maximum connecting capacity of 50 mm’ which relates to Table 1. Ctausc 6.2.2 and 7.3.2.
6.2.2 if uximum connecting capacsit
The maximum connecting capacity is the largest unprepared stranded copper conductor size in Table I that can he clamped.
Compliance shall be established in accordance with Clause 7.3.2.
6.2.3 Separate terminals br ladE viclual conductors
The bars shall be provided with separate terminals for connecting each individual incoming and outgoing cable.
Compliance shall be established in accordance with Clause 7.3.3.
6.2.4 Tunnel terminal types
One or more of the following tunnel terminal types, as delined in Clause 3.9. may be used:
(a) Tunnel terminal with screws in direct contact with the conductors.
(b) Tunnel terminal with a ferrule or plate giving indirect pressure on the conductors from thc screw –
(c) Saddle terminals for incoming conductors.
Compliance shall be established in accordance with Clause 7.3.4.
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 he 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 Jbr tunnel terminals and saddle terminals
6.5.4. 1 Number and spacing of screws in direct contact wit/i 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 an o t lie r.
(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 be established in accordance with Clause 7.6.4.
18.104.22.168 Num her of screws fbr tunnel terminals with a plate or frrule giving indirect press iire an cijo r saddle term i,ials
22.214.171.124. 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 126.96.36.199.
188.8.131.52.2 Saddle terminals
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 184.108.40.206.