Class F.

MARINE WORK.

68. Generators.

a. Must be located in a dry place.

b. Must have their frames insulated from their bed-plates.

c. Must each be provided with a waterproof cover.

d. Must each be provided with a name-plate, giving the maker's name, the capacity in volts and amperes, and the normal speed in revolutions per minute.

69. Wires.

a. Must be supported in approved moulding or conduit, except at switchboards and for portables.

b. Must have no single wire larger than No. 12 B. & S. gage. Wires to be stranded when greater carrying capacity is required. No single solid wire smaller than No. 14 B. & S. gage, except in fixture wiring, to be used.

c. Splices or taps in conductors must be avoided as far as possible. Where it is necessary to make them they must be so spliced or joined as to be both mechanically and electrically secure without solder. They must then be soldered, to insure preservation, covered with an insulating compound equal to the insulation of the wire, and further protected by a waterproof tape. The joint must then be coated or painted with a waterproof compound.

For Moulding Work.

d. Must have an approved insulating covering.

e. Must have, when passing through water-tight bulkheads and through all decks, a metallic stuffing tube lined with hard rubber. In case of deck tubes, they shall be boxed near deck to prevent mechanical injury.

f. Must be bushed with hard rubber tubing, one eighth of an inch in thickness, when passing through beams and non-water-tight bulkheads.

For Conduit Work.

g. Must have an approved insulating covering.

For unlined metal conduits, conductors must conform to the specifications given for lined conduits, and in addition have a second outer fibrous covering at least one thirty-second of an inch in thickness, and sufficiently tenacious to withstand the abrasion of being hauled through the metal conduit.

h. Must not be drawn in until the mechanical work on the conduit is completed and same is in place.

i. Where run through coal bunkers, boiler rooms, and where they are exposed to severe mechanical injury, must be encased in approved conduit.

70. Portable Conductors.

a. Must be made of two stranded conductors, each having a carrying capacity equivalent to not less than No. 14 B. & S. gage wire, and each covered with an approved insulation and covering.

Where not exposed to moisture or severe mechanical injury, each stranded conductor must have a solid insulation at least one thirty-second of an inch in thickness, and must show an insulation resistance between conductors, and between either conductor and the ground, of at least fifty megohms per mile after two weeks' submersion in water at 70 degrees Fahrenheit, and be protected by a slow-burning, tough-braided outer covering.

Where exposed to moisture and mechanical injury—as for use on decks, holds and fire-rooms—each stranded conductor shall have a solid insulation, to be approved, of at least one thirty-second of an inch in thickness and protected by a tough braid. The two conductors shall then be stranded together, using a jute filling. The whole shall then be covered with a layer of flax, either woven or braided, at least one thirty-second of an inch in thickness, and treated with a non-inflammable, waterproof compound. After one week's submersion in water at 70 degrees Fahrenheit, it must show an insulation between the two conductors, or between either conductor and the ground, of fifty megohms per mile.

71. Bell or Other Wires.

a. Shall never be run in same duct with lighting or power wires.

72. Table of Capacity of Wires.

B. & S. G.	Area Actual C. M.	No. of Strands.	Size of Strands B. & S. G.	Amperes.
19	1,288	..	..	..
18	1,624	..	..	3
17	2,048	..	..	..
16	2,583	..	..	6
15	3,257	..	..	..
14	4,107	..	..	12
12	6,530	..	..	17
..	9,016	7	19	21
..	11,368	7	18	25
..	14,336	7	17	30
..	18,081	7	16	35
..	22,799	7	15	40
..	30,856	19	18	50
..	38,912	19	17	60
..	49,077	19	16	70
..	60,088	37	18	85
..	75,776	37	17	100
..	99,064	61	18	120
..	124,928	61	17	145
..	157,563	61	16	170
..	198,677	61	15	200
..	250,527	61	14	235
..	296,387	91	15	270
..	373,737	91	14	320
..	413,639	127	15	340

73. Switchboard.

a. Must be made of non-combustible, non-absorptive insulating material, such as marble or slate.

b. Must be kept free from moisture, and must be located so as to be accessible from all sides.

c. Must have a main switch, main cut-out and ammeter for each generator. Must also have a voltmeter and ground detector.

d. Must have a cut-out and switch for each side of each circuit leading from board.

74. Resistance Boxes.

(For construction rules, see No. 60.)

a. Must be located on switchboard or away from combustible material. When not placed on switchboard they must be mounted on non-inflammable, non-absorptive insulating material.

75. Switches.

(For construction rules, see No. 51.)

a. Must not be single pole when the circuits which they control supply devices which require over 660 watts of energy.

b. When exposed to dampness, they must be enclosed in a water-tight case.

c. Must be of the knife pattern when located on switchboard.

d. Must be provided so that each freight compartment may be separately controlled.

76. Cut-Outs.

(For construction rules, see No. 52.)

a. Must be placed at every point where a change is made in the size of the wire (unless the cut-out in the larger wire will protect the smaller).

b. In places such as upper decks, holds, cargo spaces and fire-rooms, a water-tight and fireproof cut-out may be used, connecting directly to mains when such cut-out supplies circuits requiring not more than 660 watts energy.

c. When placed anywhere except on switchboards and certain places, as cargo spaces, holds, fire-rooms, etc., where it is impossible to run from center of distribution, they shall be in a cabinet lined with fire-resisting material.

d. Except for motors, searchlights and diving lamps shall be so placed that no group of lamps, requiring a current of more than 660 watts, shall ultimately be dependent upon one cut-out.

77. Fixtures.

a. Shall be mounted on blocks made from well-seasoned lumber treated with two coats of white lead or shellac.

b. Where exposed to dampness, the lamp must be surrounded by a vapor-proof globe.

c. Where exposed to mechanical injury, the lamp must be surrounded by a globe protected by a stout wire guard.

d. Shall be wired with same grade of insulation as portable conductors which are not exposed to moisture or mechanical injury.

e. Ceiling fixtures over two feet in length must be provided with stay chains.

78. Sockets.

(For construction rules, see No. 55.)

79. Wooden Mouldings.

(For construction rules, see No. 50.)

a. Where moulding is run over rivets, beams, etc., a backing strip must first be put up and the moulding secured to this.

b. Capping must be secured by brass screws.

80. Interior Conduits.

(For installation rules, see No. 25.)

(For construction rules, see No. 49.)

81. Signal Lights.

a. Must be provided with approved telltale board, located preferably in pilot-house, which will immediately indicate a burned-out lamp.

82. Motors.

a. Must be wired under the same precautions as with a current of same volume and potential for lighting. The motor and resistance box must be protected by a double-pole cut-out and controlled by a double-pole switch, except in cases where one-quarter horse power or less is used.

b. Must be thoroughly insulated. Where possible, should be set on base frames made from filled, hard, dry wood and raised above surrounding deck. On hoists and winches they shall be insulated from bed-plates by hard rubber, fiber or similar insulating material.

c. Shall be covered with a waterproof cover when not in use.

d. Must each be provided with a name-plate giving maker's name, the capacity in volts and amperes, and the normal speed in revolutions per minute.

83. Insulation Resistance.

The wiring in any vessel must test free from grounds; i. e., the complete installation must have an insulation between conductors and between all conductors and the ground (not including attachments, sockets, receptacles, etc.) of not less than the following:—

Up to 25 amperes	800,000 ohms.
Up to 50 amperes	400,000 ohms.
Up to 100 amperes	200,000 ohms.
Up to 200 amperes	100,000 ohms.
Up to 400 amperes	50,000 ohms.
Up to 800 amperes	25,000 ohms.
Up to 1,600 amperes	12,500 ohms.
All cut-outs and safety devices in place in the above.

Where lamp sockets, receptacles and electroliers, etc., are connected, one half of the above will be required.