Section 12 Installation of equipment

12.1.1 Cable runs are to be, as far as possible, straight and accessible.

12.1.2 Cables having insulating materials with different maximum-rated conductor temperatures are not to be bunched together, or, where this is not practicable, the cables are to be operated so that no cable reaches a temperature higher than that permitted for the lowest temperature-rated cable in the group.

12.1.3 Cables having a protective covering which may damage the covering of other cables are not to be bunched with those other cables.

12.1.4 The minimum internal radius or bend of installed cables is to be generally in accordance with:

12.2.1 Cables exposed to risk of mechanical damage are to be protected by metal channels or casing or enclosed in steel conduit unless the protective covering (e.g. armour or sheath) is sufficient to withstand the possible damage.

12.2.2 Cables in cargo holds and other spaces where there is exceptional risk of mechanical damage are to be suitably protected, even if armoured, unless the steel structure affords adequate protection. See also Pt 6, Ch 2, 13.6 Cables and cable installation.

12.2.3 Metal casings for mechanical protection of cables are to be efficiently protected against corrosion.

12.3.1 Metal coverings of cables are to be effectively earthed at both ends of the cable, except in final sub-circuits where earthing at the supply end only will be considered adequate. This does not necessarily apply to instrumentation cables where single point earthing may be desirable for technical reasons.

12.3.2 The electrical continuity of all metal coverings of cables throughout the length of the cable, particularly at joints and tappings, is to be ensured.

12.3.3 The lead sheath of lead-sheathed cables is not to be used as the sole means of earthing the non-current carrying parts of items of equipment.

12.4.1 Cables are to be effectively supported and secured without their coverings being damaged.

12.4.2 The distances between supports is to be chosen according to the type of cable.

12.4.3 Supports and accessories are to be robust and are to be of corrosion-resistant material or suitably corrosion inhibited before erection.

12.5.1 Penetration of watertight bulkheads or decks is to be carried out with either individual watertight glands or with packed watertight boxes carrying several cables. However carried out, the watertight integrity of the bulkheads or decks is to be maintained.

12.5.2 Cables passing through decks are to be protected by deck tubes or ducts.

12.5.3 Where cables pass through non-watertight bulkheads or structural steel, the holes are to be bushed with lead or other approved material. If the steel is at least 6 mm thick, adequately rounded edges may be accepted as the equivalent of bushing.

12.5.4 Materials used for glands and bushings are to be such that there is no risk of corrosion.

12.5.5 Where rectangular holes are cut in bulkheads or structural steel, the corners are to be radiused.

12.6.1 Metal conduit systems are to be earthed and are to be mechanically and electrically continuous across joints. Individual short lengths of conduit need not be earthed.

12.6.2 The internal radius of bend of pipes and conduit is to be not less than that laid down for cables, provided that for pipes exceeding 64 mm diameter, the internal radius of bend is not less than twice the diameter of the pipe.

12.6.3 The drawing-in factor (ratio of the sum of the cross-sectional areas of the cables to the internal cross-section area of the pipe) is not to exceed 0,4.

12.6.4 Expansion joints are to be provided where necessary.

12.6.5 Where necessary, ventilation openings are to be provided at the highest and lowest points to permit air circulation and to prevent accumulation of water.

12.6.6 Where cables are laid in trunks, the trunks are to be so constructed as not to afford passage for fire from one ‘tween deck or compartment to another.

12.6.7 Non-metallic ducting or conduit is to be of flame retardant material. PVC conduit is not to be used in refrigerated spaces or on open decks, unless specially approved.

12.7.1 Where it is necessary to use single-core cables for alternating current circuits rated in excess of 20 A, the requirements of Pt 6, Ch 2, 12.7 Cables for alternating current 12.7.2 are to be complied with.

12.7.2 Cables are to be either non-armoured or armoured with non-magnetic material.

12.7.3 If installed in pipe or conduit, cables belonging to the same circuit are to be installed in the same conduit, unless the conduit or pipe is of non-magnetic material.

12.7.4 Cable clips are to include cables of all phases of a circuit unless the clips are of non-magnetic material.

12.7.5 In the installation of two, three or four single-core cables forming respectively single-phase circuits, three-phase circuits or three-phase and neutral circuits, the cables are to be in contact with one another, as far as possible. In any event the distance between adjacent cables is not to be greater than one diameter.

12.7.6 If single-core cables of current rating greater than 250 A are run along a steel bulkhead. Wherever practicable, the cables should be spaced away from the steel.

12.7.7 Where single-core cables of rating exceeding 50 A are used, magnetic material is not to be placed between single-core cables of a group. If these cables pass through steel plates, all cables of the same circuit are to pass through a plate or gland so constructed that there is no magnetic material between the cables, and suitable clearance is provided between the cable core and magnetic material. This clearance, wherever practicable, is to be not less than 75 mm when the current exceeds 300 A. For currents between 50 A and 300 A, the clearance is to be obtained by interpolation.

12.8.1 The ends of all conductors or cross-sectional area greater than 4 mm² are to be fitted with soldering sockets, compression type sockets or mechanical clamps. Corrosive fluxes are not to be used.

12.8.2 Cables having a hygroscopic insulation (e.g. mineral insulated) are to have their ends sealed against ingress of moisture.

12.8.3 Cables with a supplementary insulating belt beneath the protective sheath are to have additional insulation at those points where the insulation of each core makes or may make contact with earthed metal.

12.9.1 If a joint is necessary it is to be carried out so that all conductors are adequately secured, insulated and protected from atmospheric action. Terminals or busbars are to be of dimensions adequate for the cable rating.

12.10.1 Alkaline batteries and lead acid batteries are not to be installed in the same compartment.

12.10.2 Large batteries are to be installed in a space assigned to the batteries only or alternatively in a deck box if such a space is not available.

12.10.3 Engine starting batteries are to be located as close as practicable to the engine(s) served. If such batteries cannot be accommodated in the battery room, they are to be installed so that adequate ventilation is ensured.

12.10.4 Where acid is used as the electrolyte, a tray of lead, or wood lined with lead, is to be provided below the cells. Alternatively, the deck below the cells is to be protected with lead or other acid-resisting material which effectually prevents any acid from lodging in contact with the ship’s structure.

12.10.5 The interiors of all battery compartments, including shelves, are to be painted with corrosion-resistant paint.

12.10.6 Switches, fuses and other electrical equipment liable to cause an arc are not to be fitted in battery compartments.

12.10.7 Batteries are to be so arranged that each cell or crate of cells is accessible from the top and at least one side.

12.10.8 Cells or crates are to be carried on non-absorbent insulating supports. Similar insulators are to be fitted to prevent any movement of cells arising from the motion of the ship.

12.10.9 Battery compartments are to be ventilated by an independent ventilating system.

12.10.10 Natural ventilation may be employed if ducts can be run directly from the top of the compartment to the open air with no part of the duct more than 45° from the vertical. If natural ventilation is impracticable, mechanical ventilation is to be provided. Interior surfaces of ducts and fans are to be protected against corrosion. Fan motors are not to be located in the air stream.

12.10.11 All openings through the battery compartment bulkheads or decks, other than ventilation openings, are to be effectively sealed to reduce the possibility of escape of gas from the battery compartment into the ship.

12.10.12 Where practicable, battery lockers are to be ventilated in the same manner as battery compartments.

12.10.13 Deck boxes are to be adequately ventilated and means provided to prevent ingress of water.

12.10.14 A permanent notice is to be fitted to all battery compartments prohibiting naked lights and smoking.

12.11.1 Lighting of cargo spaces is to be controlled by multi-pole linked switches situated outside these spaces. Provision is to be made for the complete isolation of these circuits and locking in the OFF position of the means of control.

12.12.1 Where it is necessary to earth the non-current carrying parts of portable or transportable equipment, an effective means of earthing is to be provided at the socket outlet.

12.12.2 In all wet situations, socket outlets and plugs are to be effectively shielded against rain and spray and are to be provided with means of maintaining this quality after removal of the plug.