TRAMWAY.
No. 10 of 1902.
1433
1. Any dynamo used as a generator shall be of such pattern and construction as to be capable of producing a continuous current without appreciable pulsation.
2. One of the two conductors used for transmitting energy from the generator to the motors shall be in every case insulated from earth, and is hereinafter referred to as the "line"; the other may be insulated throughout, or may be uninsulated in such parts and to such extent as is provided in the following rules, and is hereinafter referred to as the "return".
3. Where any rails, on which cars run, or any conductors laid between or within three feet of such rails, form any part of a return, such part may be uninsulated. All other returns or parts of a return shall be insulated, unless of such sectional area as will reduce the difference of potential between the ends of the uninsulated portion of the return below the limit laid down in rule 7.
4. When any uninsulated conductor laid between or within three feet of the rails forms any part of a return, it shall be electrically connected to the rails at distances apart not exceeding one hundred feet by means of copper strips having a sectional area of at least one-sixteenth of a square inch, or by other means of equal conductivity.
5. When any part of a return is uninsulated, it shall be connected with the negative terminal of the generator, and in such case the negative terminal of the generator shall also be directly connected, through the current indicator hereinafter mentioned, to two separate earth connexions which shall be placed not less than twenty yards apart: Provided that in place of such two earth connexions the company may make one connexion to a main for water supply of not less than three inches internal diameter, with the consent of the owner thereof and of the person supplying the water, and provided that where, from the nature of the soil or for other reasons, the company can show to the satisfaction of an inspecting officer of the Government that the earth connexions herein specified cannot be constructed and maintained without undue expense, the provisions of this rule shall not apply. The earth connexions referred to in this rule shall be constructed, laid, and maintained so as to secure electrical contact with the general mass of earth, and so that an electro-motive force, not exceeding four volts, shall suffice to produce a current of at least two amperes from one earth connexion to the other through the earth, and a test shall be made at least once in every month to ascertain whether this requirement is complied with. No portion of either earth connexion shall be placed within six feet of any pipe except a main for water supply of not less than three inches internal diameter which is metallically connected to the earth connexions with the consents hereinbefore specified.
6. When the return is partly or entirely uninsulated, in the construction and maintenance of the tramway, the company shall (a) so separate the uninsulated return from the general mass of earth, and from any pipe in the vicinity; (b) so connect together the several lengths of the rails; (c) adopt such means for reducing the difference produced by the current between the potential of the uninsulated return at any other point; and (d) so maintain the efficiency of the earth connexions specified in the preceding rules, as to fulfil the following conditions, viz.:-