New Zealand Gazette – 1927 – No. 48

Page 2417

✨ Electrical Wiring Regulations

JULY 12.] THE NEW ZEALAND GAZETTE. 2417

CLASS W.—WOOD CASING.

All types of cables specified in Regulation 84 of these regulations as approved types may be enclosed in wood casing, provided that such casing be of kaikawaka or other timber approved by the Chief Electrical Engineer; and, further, that—
(a) Wood casing may be used only in dry situations and on the surface.
(b) It may not be fixed in contact with gas-pipes or water-pipes, or immediately below the latter, or in places where liable to be damaged by rodents, and that in no case shall it come within 12 in. above a floor.
(c) The capping is secured by incorrodible screws.
(d) If the casing forms part of ornamental woodwork, ready access must be provided to the cables contained therein.
(e) Wood casing shall be so constructed that the width of the fillet between the grooves is at least ½ in., and the thickness of the outside at least ¼ in.
(f) Wood casing shall be supported continuously and enclose the conductors throughout their entire length, the joints being close-fitted and all angles mitred.
(g) Under no circumstances shall wood casing be used for power, or on pressures exceeding 250 volts to earth, or for enclosing service-mains or passing through party walls.

THIRD SCHEDULE.

Tables.

The following is a list of the tables and of the regulations in which they are referred to :—
TABLE I.—Dimensions, Weight, and Resistance of Solid and Stranded Circular Conductors .. 75 (1).

TABLE II.—Comparison between the Old Standard Sizes of Conductors and the New Standard Sizes set out in B.S.S. No. 7 .. —
TABLE III.—Flexible Cables: Dimensions and Resistance of Conductors .. 75 (2).
TABLE IV.—Vulcanized-rubber Cables: Current-carrying Capacity (subject to Voltage-drop) and Corresponding Fall in Pressure .. 80 (b), 131 (4).
TABLE V.—Impregnated-paper and Lead-covered Cables: Current-carrying Capacity (subject to Voltage-drop) and Corresponding Fall in Pressure .. 80 (b), 131 (4).
TABLE VI.—Rubber-insulated Flexible Cables: Current-carrying Capacity .. 81.
TABLE VII.—Flexible Cords: Dimensions and Resistance of Conductors .. 75 (3).
TABLE VIII.—Flexible Cords: Thickness of Insulation and Current-carrying Capacity .. 81 (1), 91 (3), 92.
TABLE IX.—Insulation Resistance of Cables .. 95–97.
TABLE X.—Test Pressures for Flexible Cords 98 (1).
TABLE XI.—Insulation Resistance of Flexible Cords having Vulcanized-rubber Insulation 98 (3).
TABLE XII.—Permissible Number of Conductors in Conduits and Capacity of Conduits (Type B, screwed, B.S.S. No. 31) for the Drawing-in of Conductors .. 137 (3).
TABLE XIII.—Approximate Fusing Currents of Copper Wires in Free Air .. 68 (b) (ii).
TABLE XIV.—Approximate Fusing Currents of Lead-tin Alloy (Lead 75 per Cent., Tin 25 per Cent.) Wires in Free Air .. 68 (b) (ii).
TABLE XV.—Flexible Cords: Types to be used .. 117.
TABLE XVI.—Flexible Cables and Cords: Carrying-capacity for fusing purposes .. 68 (b) (iii), 71 (4).

TABLE I.—DIMENSIONS, WEIGHT, AND RESISTANCE OF SOLID AND STRANDED CIRCULAR CONDUCTORS.

Nominal Area.	Calculated Area.	Number and Diameter (In.) of Wires comprising Conductor.	Over-all Diameter of Conductor.	Weight per 1,000 Yards of Conductor.	Resistance per 1,000 Yards at 60° F.
					Standard.	Maximum allowable for Plain Wires.	Maximum allowable for Tinned Wires
1.	2.	3.	4.	5.	6.	7.	8.
Sq. in.	Sq. in.		In.	lb.	Ohms.	Ohms.	Ohms.
0·001	0·001018	1/·036	0·036	11·77	23·59	24·29	24·53
0·0015	0·001521	1/·044	0·044	17·58	15·79	16·26	16·42
0·002	0·001943	3/·029	0·062	23·37	12·36	12·61	12·85
0·003	0·002994	3/·036	0·078	36·02	8·019	8·180	8·260
0·003	0·003217	1/·064	0·064	37·20	7·463	7·687	7·761
0·0045	0·004546	7/·029	0·087	54·39	5·281	5·387	5·493
0·007	0·007005	7/·036	0·108	83·81	3·427	3·496	3·530
0·01	0·01046	7/·044	0·132	125·2	2·294	2·340	2·363
0·0145	0·01462	7/·052	0·156	174·9	1·643	1·675	1·692
0·0225	0·02214	7/·064	0·192	264·9	1·084	1·106	1·117
0·03	0·02840	19/·044	0·220	340·4	0·8468	0·8637	0·8721
0·04	0·03960	19/·052	0·260	475·5	0·6063	0·6184	0·6244
0·06	0·05999	19/·064	0·320	720·3	0·4002	0·4082	0·4122
0·075	0·07592	19/·072	0·360	911·6	0·3162	0·3225	0·3257
0·1	0·1009	19/·083	0·415	1211·0	0·2380	0·2427	0·2451
0·12	0·1168	37/·064	0·448	1403·0	0·2056	0·2097	0·2118
0·15	0·1478	37/·072	0·504	1776·0	0·1625	0·1657	0·1673
0·2	0·1964	37/·083	0·581	2360·0	0·1223	0·1247	0·1259
0·25	0·2465	37/·093	0·651	2963·0	0·09738	0·09933	0·1003
0·3	0·3024	37/·103	0·721	3635·0	0·07939	0·08098	0·08177
0·4	0·4064	61/·093	0·837	4886·0	0·05908	0·06026	0·06085
0·5	0·4985	61/·103	0·927	5994·0	0·04816	0·04913	0·04961
0·6	0·6062	91/·093	1·023	7290·0	0·03961	0·04040	0·04079
0·75	0·7435	91/·103	1·133	8942·0	0·03229	0·03294	0·03326
0·85	0·8459	127/·093	1·209	10175·0	0·02838	0·02895	0·02923
1·0	1·0376	127/·103	1·339	12481·0	0·02314	0·02360	0·02383

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🏗️ Electrical Wiring Regulations, 1927 (continued from previous page)

Domain🏗️ Infrastructure & Public Works
Dated11 July 1927
KeywordsRegulations, Electrical Wiring, Safety, Compliance, Wood Casing, Tables, Conductors, Cables, Current-carrying Capacity, Insulation Resistance

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