7.17.2 - The marina electrical installation

As for caravans, the neutral of a PME system must not be connected to the earthed system of a boat so that the hazards which follow the loss of continuity in the supply PEN conductor are avoided. This rules out the use of PME supplies for marinas. Where this is the supply provided, it must be converted to a TI' system at the main distribution board by provision of an separate earth electrode system of driven rods or buried mats with no overlap of resistance area with any earth associated with the PME supply. If the marina is large enough, it may be that the supply company will provide a separate transformer and a TN-S system.

Shock protection
Protection by obstacles or by placing out of reach are not acceptable as methods of preventing direct contact. A non-conducting location must not be used for protection from indirect contact. Where a TN-S system is used, indirect protection must be provided by an RCD which breaks all poles unless protection is provided by an on-shore isolating transformer.

Wiring Systems
No aluminium cables may be used in marina installations.
Acceptable cables for fixed wiring are:
- those with thermoplastic, thermosetting or elastomeric insulation and sheath installed
- in non-flexible non-metallic conduit, or in heavy-duty galvanised conduit,
- mineral insulated cable with extruded p.v.c. covering,
- armoured cables with sheaths of thermoplastic or elastomeric material.

A boat will move relative to the land due to wind and waves. Cables must be selected and installed so that mechanical damage as a result of tidal and other movement of floating structures is prevented. Cabling to bridge ramps, pontoons and movable jetties must be carried out in flexible cables with EPR or thermosetting insulation and sheaths. Overhead lines are not permitted. Conduit installations must be provided with apertures or holes to allow for drainage.

It should be noted that p.v.c. cables are not usually suitable for continuous immersion in water. Cables intended to be permanently immersed to a depth of 4 m or more should be sheathed with lead; where the immersion is less than 4 m, cables should be armoured and provided with polythene bedding and outer sheath. Due to possible problems with corrosion, cable armouring must not be relied upon as a circuit protective conductor. A separate CPC must be provided to which the armouring is securely connected. Cable terminations must be protected against corrosion by selection of suitable materials, or by the application of grease or mastic or paint. Buried cables will be required on-shore. It must be remembered that such situations will be subjected to very weighty traffic as boat trailers are moved. Unless the buried cables are above the water table they must be suitable for continuous immersion.

Distribution boards
Distribution boards must be protected to IP44, and against the ingress of dust and sand. Construction of glass reinforced plastic (GRP) gives better corrosion protection than galvanised steel. Where mounted on fixed jetties, they must be at a minimum of 1 m above the high water level; on floating jetties, they must be at least 750 mm above the water. Boards must be fitted with locks to prevent unauthorised access, and with internal barriers to prevent contact with live parts (to IP 2X) when the doors are open. Low power heaters may be needed within the boards to prevent excessive condensation.

Socket outlets
A common installation method is to provide a feed from the shore to a floating pontoon via a bridge or ramp, and then to equip the pontoon with socket outlets to feed the craft moored to it. Socket outlets may be single- or three-phase. Where multiple single-phase sockets are installed on the same pontoon, they must all be connected to the same phase of the supply unless fed through isolating transformers. All socket outlets must be to BS EN 60309-2 with keyways at 6R, protected to IPX4 minimum, coloured red if three-phase and blue if single-phase. Single-phase sockets are usually rated at 16 A and three-phase at 32 A, although higher ratings may be installed where the need arises. Socket outlets should be positioned as close as possible to the berth of the vessel they feed, with a minimum of one socket per berth, although up to six sockets may be provided in a single enclosure. Each socket outlet must be provided with a means of isolation which breaks all poles on T[ systems, and must be protected by an overcurrent device such as a fuse or a circuit breaker. Groups of socket outlets must be RCD protected. Each socket or group of sockets must be provided with a durable and legible notice giving instructions for the electricity supply (see {Table 7.10}); alternatively the notice must be placed in a prominent position or must be issued to each berth holder.

Table 7.10 - Instructions for electricity supply
Berthing instructions for connection to the shore supply
This marina provides power for use on you leisure craft with a direct connection to the shore supply which is connected to earth.  Unless you have an isolating transformer fitted on board to isolate the electrical system of your craft from the shore supply system, corrosion through electrolysis could damage your craft or surrounding craft.
ON ARRIVAL
1	Ensure that the supply is switched off before inserting the craft plug.
2	The supply to the berth is ***V, **Hz. The socket outlet will accommodate a standard marine plug coloured ****.
3	For safety reasons, your craft must not be connected to any other socket outlet than that allocated to you and the internal wiring on your craft must comply with the appropriate standards.
4	Every effort must be made to prevent the connecting flexible three-core cable from falling into the water if it should become disengaged. For this purpose, securing hooks are provided alongside socket outlets for anchorage at a loop of tie cord.
5	For safety reasons, only one leisure-craft connecting cable may be connected to any one socket outlet.
6	The connecting flexible cable must be in one length, without signs of damage, and not containing joints or other means to increase it’s length.
7	The entry of moisture and salt into the leisure-craft inlet socket may cause a hazard.  Examine carefully and clean the plug and socket before connecting the supply.
8	It is dangerous to attempt repairs or alterations, if any difficulty arises, contact the marina management.
BEFORE LEAVING
1	Ensure that the supply is switched off before the connecting cable is disconnected and any tie cord loops are unhooked.
2	The connecting flexible cable should be disconnected first from any marina socket outlet and then from the leisure craft inlet socket.  Any cover that may be provided to protect the inlet from the weather should be securely replaced.  The connecting flexible cable should be coiled up and stored in a dry location where it will not be damaged.
**** Appropriate figures and colours must be inserted either 220-250 V blue, or 380-415 V red.

Inspection and testing
Inspection and testing must be carried out in full accordance with BS 7671 (see {Chapter 8}). Periodic testing must be at least annually, but may need to be more frequent if the marina is exposed or subject to misuse.