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at least four feet above the floor, except as provided in paragraph g below.

f. All portable lights must be equipped with approved keyless sockets of moulded composition or metal-sheathed porcelain type. These sockets must be equipped with handle, hook and substantial guard.

g. Switchboards and charging panels, at or upon which are mounted devices which in operation may produce a spark, must be located in a room or enclosure provided for the purpose unless all such spark producing devices are at least four feet above the floor or surrounded by vapor proof enclosures.

h. Motors or dynamos, not actually a part of a vehicle, if not located at least four feet above the floor, must be of the fully enclosed type. Motors located four feet or more above the floor, if not of the fully enclosed type, must be provided with wire screen of not less than No. 14 mesh over openings at commutator end.

8 443. Electric cranes.-All wiring, apparatus, etc., not specifically covered by special rules herein given, must conform to the general requirements of this chapter except that the switch required by $ 2080 of this chapter for each motor may be omitted.

a. Wiring.-1. All wires except bare collector wires, those between resistances and contact plates of rheostats and those subjected to severe external heat, must be approved rubber-covered and not smaller in size than No. 12 B. & S. gage. Insulation on wires between resistances and contact plates of rheostats must conform to paragraph d hereof, while wires subjected to severe external heat must have approved slow-burning insulation.

12. All wires excepting collector wires and those run in metal conduit or approved flexible cable must be supported by knobs or cleats which separate them at least 1 inch from the surface wired over, but in dry places, where space is limited and the distance between wires as required by 8 426h of this chapter cannot be obtained, each wire must be separately encased in approved flexible tubing securely fastened in place.

Collector wires must be supported by approved insulators so mounted that even with the extreme movement permitted the wires will be separated at all times at least 192 inches from the surface wired over. Collector wires must be held at the ends by approved strain insulators.

3. Main collector wires carried along the runways must be rigidly and securely attached to their insulating supports at least every 20 feet, and separated at least 6 inches when run in a horizontal plane; if not run in a horizontal plane, they must be separated at least 8 inches. If spans longer than 20 feet are necessary the distance between wires must be increased proportionately, but in no case shall the span exceed 40 feet.

4. Where bridge collector wires are over 80 feet long, insulating supports on which the wires may loosely lie must be provided at least every 50 feet.

Bridge collector wires must be kept at least 292 inches apart, but a greater spacing should be used whenever it may be obtained.

5. Collector wires must not be smaller in size than specified in the following table for the various spans:

Distance between
Rigid Supports,

feet.

Size Wire
Required
B. & S.

0 to 30. 30 to 60. Over 60.

6 4 2

b. Collectors must be so designed that sparking between them and collector wires will be reduced to a minimum.

c. Switches and cut-outs.-1. The main collector wires must be protected by a cut-out and the circuit controlled by a switch. Cutout and switch shall be so located as to be easy of access from the floor.

2. Cranes operated from cabs must have a cut-out and switch connected into the leads from the main collector wires and so located in the cab as to be readily accessible to the operator.

3. Where there is more than one motor on a single crane, each motor lead must be protected by a cut-out located in the cab if there is one.

d. Controllers must be installed according to $ 204 of this chapter, except that if the crane is located out doors the insulation on wires between resistances and contact plates of rheostats must be rubber where the wires are exposed to moisture and insulation is necessary and also where they are grouped. If the crane operates over readily combustible material the resistances must be placed in an enclosure made of non-combustible material, thoroughly ventilated and so constructed that it will not permit any flames or molten metal to escape in the event of burning out the resistances. If the resistances are located in the cab, this result may be obtained by constructing the cab of non-combustible material and providing sides which enclose the cab from its floor to a height of at least 6 inches above the top of the resistances.

e. The motor frames, the entire frame of the crane and the tracks must be permanently and effectively grounded.

§ 444. Wires, high potential systems in central stations, sub-stations and transformer vaults. Special permission in writing may be given for the installation of wires of high potential systems under such restrictions as the commissioner may prescribe. § 445. Transformers, high potential.

.-a. Transformers must be located as near as possible to the point at which the primary wires enter the building.

b. Transformers must be placed in an enclosure constructed of fireproof material. The enclosure shall have no opening to the building except through an approved tight-fitting fire door. It shall be ventilated in some approved manner, be used only to contain the transformers and other high potential regulating devices, and be kept securely locked to prevent access by other than responsible persons. Suitable oil drains and guard sills shall be provided, as may be required by the commissioner.

c. The transformer case must be permanently and effectually grounded.

447. Wires, extra high potential.

:-a, Primary wires must not be brought into or over buildings, except power stations, sub-stations and transformer vaults.

b. Secondary wires must be installed under rules for high-potential systems when their immediate primary wires carry a current at a potential of over 3,500 volts, unless the primary wires are installed in accordance with the requirements of article 3 of this chapter or are entirely underground.

ARTICLE 5

FITTINGS, MATERIALS AND DETAILS OF CONSTRUCTION

(As amended by ord., effective May 29, 1916) Sec. 548. Fittings, materials and details of construction.

$ 549. Wires, general.
$ 550. Rubber covered wires.
$ 551. Flexible cords.
§ 552. Fixture wire.

553. Conduit wire.
$ 554. Armored cable and cord.
$ 555. Slow burning weatherproof wire.

556. Slow burning wire. § 557. Weatherproof wire.

558. Metal conduits. $ 559. Outlet, junction and flush switch boxes. Š 560. Metal mouldings. Š 561. Tubes and bushings.

562. Cleats.

563. Flexible tubing. Š 564. Knobs. § 565. Switches.

566. Circuit breakers.

567. Cut-outs. § 568. Fuses. § 569. Panel boards. § 570. Cabinets and cut-out boxes. § 571. Rosettes.

572. Sockets, including lamp receptacles.
8 573.
Š 574. Arc lamps.
8.575.
§ 576. Insulating joints.
§ 577. Fixtures.
§ 578. Rheostats, resistance boxes and equalizers.
$ 579. Auto-starters.

580. Reactive coils and condensers.
581. Transformers, low potential.

582. Lightning arresters.
$ 583. Electric signs (for low potential systems only).

584.

Sec. 548. Fittings, materials and details of construction.-The re quirements and provisions of this article prescribe the general characteristics and classifications of fittings, materials and details of construction. Specifications for performance of fittings and materials, both under test and in service, shall be as prescribed from time to time by the commissioner. All fittings, materials and details of construction must be approved by the commissioner before being placed in service.

$ 549. Wires, general.-a. Wires, cables and cords of all kinds designed to meet the following specifications must have a distinctive marking the entire length of the coil so that they may be readily identified in the field. They must also be plainly tagged or marked as follows:

Wires described under $ 557 need not have the distinctive markings but are to be tagged.

1. The maximum working pressure or voltage for which the wire was tested or approved. This may be omitted for the wires described under 88 555, 556 and 557 of this chapter.

2. The words “National Electrical Code Standard."

3. Name of the manufacturing company and, if desired, trade name of the wire.

4. Month and year when manufactured.

5. The proper type letter for the particular style of wire or cable as given in the following schedule for each type of insulation.

RS—Rubber coated single braided for voltage. .

0–600 RS-15—Rubber covered single braided for maximum voltage 1500 RS-25—Rubber covered single braided for maximum voltage 2500 RS–35—Rubber covered single braided for maximum voltage 3500 RS-50—Rubber covered single braided for maximum voltage 5000 RS-70—Rubber covered single braided for maximum voltage 7000 RD, RD15—Rubber covered double braided, etc. RSL-Rubber covered, single braided, leaded. RDL–Rubber covered,, double braided, leaded. AC—Wires for use in armored cable. ACL-Leaded wires for use in armored cable.

b. Conductors or the strands of conductors must not vary in either diameter or in conductivity more than an approved per cent. from the standards adopted by the American Institute of Electrical Engineers.

$ 550. Rubber-covered wire. a. Conductors.—No individual conductor, whether solid or stranded, shall be less than No. 14 B. & S. gage in nominal size.

All conductors and the individual wires of stranded conductors shall be tinned.

b. Insulation. Conductors shall be insulated for their entire length with a properly applied and properly vulcanized rubber compound.

The insulation must be of the nominal thickness given in the following table, the requirements of which vary according to the sizes of conductors and the maximum working pressure:

Table of Thickness of Rubber Insulation for Rubber-Covered Wires

and Cables in 64th Inches

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c. Coverings. All single conductor rubber-insulated wires and cables must have a covering of fibrous material applied directly to the surface of the insulating wall.

For any single conductor wire there shall be at least one braid for sizes from No. 14 to and including No. 8. For all single conductor cables larger than No. 8 there must be at least two braids or a tape and a braid.

For twin wires and twisted pair wires and for all multiple conductor cables there shall be a fibrous covering on each individual wire and in addition a braid enclosing the bunched conductors.

For certain special service conditions, one or more additional coverings of fibrous material or of lead are required.

Fibrous coverings may be either braid or tape, but tape shall not be used for the outer covering. All braids must be impregnated with a moisture-proof compound.

Lead coverings may be applied to single or multiple conductors. Lead covered multiple conductor cable with more than two conductors must, in all cases, have the conductors spirally laid.

In all cases, the individual conductors in lead covered cable must have a fibrous covering and, except for two conductor cables, with conductors parallel, there must be a fibrous covering over bunched conductors.

The thickness of lead covering shall, in all cases, be that specified for cables for the various sizes and forms.

8 551. Flexible cords.--For pendant lamps and for portable use, inuding elevator lighting and control cables, and theatre stage and border-light cables.

a. These cords and cables must comply with the requirements of 8 549 a and b of this chapter.

b. Conductors. Each conductor must have a carrying capacity not less than that of a No. 18 B. & S. gauge wire and be built up from wires of approved sizes.

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