External Electrical System Design

The external electrical system can include exterior lighting, pathway lighting, garden lighting, power to sheds, power to detached garages, power to hot tubs, power to swimming pools, power to stables, power to hard standings, power to patios, power to gardens, power operated gates.

Clearly the above list includes many items that the average dwelling will never incorporate, however the list has to include those items just incase they are to be incorporated.

As with the internal electrical systems certain principles have to be established. Obviously every installation has to comply with the relevant building regulations and wiring regulations this compliance extends to outbuildings whether a small wooden shed or an olympic size swimming pool. Where electrical equipment is to be installed outdoors the selection of that equipment must include the requirement to be to a minimum standard of BSEN 60309-2 IP 55; note any IP rating equal to or greater than 55 complies; for the installer the question is therefore how to maintain that IP rating when the cables are connected. The best solution is to purcase equipment with threaded entries, if the equpment does not have threaded entries then holes have to be cut into enclosures, by tradition holes saws are used for this purpose these invariably butcher the enclosure by cutting oversize holes, a better solution is to use hole punches which cut an exact size hole. Ideally any cable entries should be from below, the converse is also true the worst place for cable entries is on top. It is then essential to maintain the IP rating when the cables/conduit are connected.

Connection by conduit to external equipment is deprecated as conduit has multiple water ingress points because there are lids and covers which are necessary to install the wires a better method is to use armoured cables. This type of cable requires glands at the points of termination, the interface between the gland and enclosure needs to be sealed against water ingress by using a fibre washer.

Where a building is to be supllied with electricity then the logical system to adopt is for that building to be equipped with it's own consumer unit, similarly where a facility such as an outdoor swimming pool is to be supplied, which requires multiple supplies, then a consumer unit suitably located should be installed, weatherproof consumer units should only be considered if there is no other option as there will be multiple cable entries into the unit; all of which are a possible points of water ingress.