Summary of General Guidelines -Circuit Design

Summary of General Guidelines -Circuit Design Points : Summary of General Guidelines -Circuit Design, Lighting Circuits, Power Circuits Lighting Circuits 1. Unless the accessories being used are designed to accept wiring larger than 1.5 mm, (or you intend to use connector/junction boxes at each luminaire location which will accept larger cable sizes), or unless the sub-main cables are very short (so that they have no effective voltage losses) then aim to fuse circuits at 5-6 Ampere and load the protective device to around 1000 VA (5A), 1200 VA (6A) for normal circuits and 500- 600 VA for essential or ‘means of escape’ circuits.
2. Remember to use the ‘1.8’ factor for discharge lighting.
3. Keep a circuit to a maximum length of 25 metres if fully loaded.
4. Decide on phasing - either one phase per floor if this is obvious or else split the phases by area. [Don’t worry too much about balancing circuits equally over the three phases. There is no guarantee that the client will use the installation evenly, so an equal area design technique will be perfectly acceptable and any more lightly loaded phase can be ‘balanced’ elsewhere on other fuse-boards within the installation].
5. Allow at least one fuse-board for every 500 m2 of floor area (or 1200 m2 for a three phase board being used to feed single phase circuits).
6. Schedule the luminaries onto circuits and fuse-boards noting the information either on a drawing or in tabular form whichever is more convenient. Power Circuits 1. Keep small power equipment on the same phase as the lighting within an area.
2. Design as many socket outlets as necessary to offer fle4xibility of use for the client.
3. Allow one ring circuit for each 100 m2 of floor area served by the socket outlets on earthing
4. Position one General Purpose Power Fuse-board adjacent to each Lighting Fuse-bard.
5. Schedule the circuits to fuse-boards noting the information either on a drawing or in tabular form whichever ‘s more convenient.
6. Use radial circuits fed at say 15 or 20 A for one or two sockets or individual items, but consider the use of ring circuits above this number.
7. Keep heavy, permanent loads such as water or space heating off the ring on their own separate circuits.