JULY 12.] THE NEW ZEALAND GAZETTE. 2415 provided in the outer conductor either a single-pole overload circuit-breaker on that pole which is connected to the outer conductor, or a single-pole switch and single-pole fuse.
(2) Where the neutral-conductor is not multiple-earthed,
there shall be provided either a double-pole overload circuit-
breaker or a double-pole switch with a fuse on each pole, but
where the neutral is known to be earthed at the source of
supply without a circuit-breaker or added resistance, the fuse
in the neutral may be omitted.
(3) For all two-conductor submains or circuits taken from
the outers, either a double-pole overload circuit-breaker or
a double-pole switch with a fuse on each pole shall be provided.
(4) A fuse or unlinked switch or unlinked circuit-breaker
shall not in any case be included in the neutral conductor,
but this requirement shall not prohibit the provision of an
isolating-link for testing purposes.
E. Two-PHASE THREE-WIRE Systems.

1. For each generator or service main there shall be pro-
   vided—
   (a) Where the common return is multiple-earthed, either
   a double-pole overload circuit-breaker controlling
   the outer conductors or a double-pole switch con-
   trolling the outer conductors with a fuse in each
   outer.
   (b) Where the common return is not multiple-earthed,
   either a triple-pole circuit-breaker with overload
   trips in the outer conductors only or a triple-pole
   switch with a fuse in each outer.
2. (1) To control each outgoing submain or circuit from
   the switchboard in the case of a three-conductor circuit there
   shall be provided—
   (a) When the common return is multiple-earthed, either a
   double-pole overload circuit-breaker controlling the
   outer phase conductors or a double-pole switch
   controlling the outer phase conductors with a fuse
   in each conductor except the common return.
   (b) When the common return conductor is not multiple-
   earthed, either a triple-pole circuit-breaker with
   overload trips on each phase or a triple-pole switch
   with a fuse on each conductor except the common
   return.
   (2) A triple-pole switch controlling any three-conductor
   circuit shall not connect the outer conductors to the supply
   before connecting the common return, or open the common
   return before the outer conductors have been opened.
3. (1) To control each outgoing submain or circuit from
   the switchboard in the case of a two-conductor circuit taken
   from the multiple-earthed common return and one outer
   there shall be provided in the outer conductor either a single-
   pole overload circuit-breaker or a single-pole switch and a
   single-pole fuse.
   (2) Where the common return conductor is not multiple-
   earthed, there shall be provided either a double-pole overload
   circuit-breaker or a double-pole switch with a fuse on each
   pole, but where the common return is known to be earthed
   at the source of supply without a circuit-breaker or added
   resistance the fuse in the common return may be omitted.
4. A fuse or unlinked switch or unlinked circuit - breaker
   shall not in any case be included in the common return con-
   ductor, but this requirement shall not prohibit the provision
   of an isolating-link for testing purposes.
   F. Two-PHASE Four-WIRE SYSTEMS.
5. For each generator or service main, when the supply
   is derived from an external source, there shall be provided
   either a four-pole circuit-breaker with overload trips on each
   phase or a four-pole linked switch with a fuse on each con-
   ductor.
6. For each outgoing four-conductor submain or circuit
   from the switchboard, there shall be provided either a four
   pole circuit-breaker with overload trip on at least one conductor
   of each phase or a four-pole linked switch with a fuse on each
   conductor.
7. For each outgoing two-wire submain or circuit from the
   switchboard, there shall be provided either a double-pole
   circuit-breaker with overload trip on at least one conductor
   or a double-pole switch with a fuse on each conductor.
   Part II.—Minimum Requirements as to Instruments to be
   provided for Generator Switchboards.
   A. Two-WIRE SYSTEMS.
8. When only one generator is installed, one ammeter and
   one voltmeter shall be provided.
9. When more than one generator is installed, the gene-
   rators being arranged to run in parallel, an ammeter for
   each generator and one voltmeter for use on any generator
   shall be provided. The voltmeter shall be fitted with a double-
   pole multiple-way switch or plug.
10. (1) When more than one generator is installed, the
    generators being arranged to run in parallel, an ammeter for
    each generator, and two voltmeters shall be provided, and if
    the current be alternating a synchronizing-device for paral-
    leling purposes shall also be provided.
    (2) For compound wound generators the ammeter shall be
    connected on the pole opposite to that to which the equalizer
    connection is made.
    (3) When more than two generators are installed, one of the
    voltmeters shall be fitted with a double-pole multiple-way
    switch or plug for use on any generator. The other voltmeter
    shall be permanently connected to the bus-bars.
    B. THREE-WIRE SYSTEMS (D.C. OR SINGLE-PHASE).
11. In addition to the instruments required for two-wire
    systems a voltmeter shall be connected between the neutral
    and each outer-bus bar.
12. There shall also be provided in the main neutral conductor
    a central zero ammeter if direct current, or a central zero
    wattmeter if alternating current.
    C. Two-PHASE AND THREE-PHASE SYSTEMS.
13. When only one generator is installed, an ammeter on
    each phase, or one ammeter with a two- or three-phase transfer-
    switch, as the case may require, and one voltmeter shall be
    provided.
14. When more than one generator is installed, the gene-
    rators being arranged to run in parallel, for each generator an
    ammeter on each phase, or one ammeter with a two- or three-
    phase transfer-switch, as the case may require, shall be
    provided.
15. There shall also be provided two voltmeters and a syn-
    chronizing device for paralleling purposes. One of these
    voltmeters shall be fitted with a double-pole multiple-way
    switch or plug for use on any generator. The other voltmeter
    shall be permanently connected to one phase of the bus-bars.
    All these voltmeter connections shall be made to the same
    phase in each case.
    Part III.—Conditions governing the Use of certain Types of
    Cables and of Steel Screwed Conduit and Wood Casing.
    CLASS L.—TAPEd AND BRAIDED CABLes.
16. In no case shall Class L wiring be used unless permission
    in writing is first obtained from the electrical supply authority,
    which shall give such permission only in respect of the use of
    such wiring in situations where the use of encased wiring is
    not practicable.
17. Taped and braided cables such as are specified in para-
    graph (b) of Regulation 84 of these regulations may be used
    without the further protection of conduit or casing, provided
    that—
    (a) They are open to view throughout their length, and,
    in particular, are not installed under floors or within
    partitions or buried in plaster.
    (b) They are kept away from all structural metal-work.
    (c) They are adequately protected in any position in which
    they would be liable to mechanical damage, and
    wherever they are within 6 ft. above the floor.
    (d) They are not in electrical or mechanical contact with
    gas or water pipes.
    (e) They are secured by porcelain cleats or insulators,
    which are so spaced as to prevent any two or more
    cables coming into contact, and which have smooth
    or rounded edges that will not indent or damage the
    braiding.
    (f) In all situations they are spaced not less than $\frac{1}{2}$ in.
    from walls, ceilings, or other structures to which
    they are attached by means of porcelain cleats or
    insulators, which are of non-absorbent material and
    the fixings of which are of non-absorbent non-rusting
    material.
    (g) When passing through floors, walls, partitions, or
    ceilings they are protected by being enclosed in
    metal, porcelain, or non-absorbent, non-ignitable
    conduits, the ends of which are bushed or so arranged
    as to prevent abrasion, such conduits, when in
    damp situations, being bitumen-filled.
    (h) When passing through party walls or fire-resisting
    floors, the conduits referred to in the last preceding
    paragraph are close-fitting, and the holes through
    which they pass are plugged with fireclay, or similar
    non-ignitable material, no space through which
    fire might spread being |left around or inside the
    conduits.
    CLASS M.—METAL-SHEATHED CABLEx.
18. Metal-sheathed cables, as specified in paragraphs (h)
    and (j) of Regulation 84 of these regulations are suitable for
    power-work, and may be used for that purpose only.