The following typical characteristics apply to residential and light commercial/industrial premises for low voltage supplies up to 630 amps. You may find these useful when completing BS 7671 Electrical Installation Certificates.Nominal Voltage U/Uo = 400/230vNominal frequency f = 50 HzProspective fault current Ipt: 25kA (3 phase), 16kA (1 phase)External loop impedance Ze:0.35 ohms typical maximum for TNCS system0.8 ohms typical maximum for TNS systemThe Ze values may be higher on older networks and should be verified by measurement.Supply protective device characteristicsType BS1361: up to 100 ampsBS88 part 5: 200 amps and aboveNominal current rating100 amps maximum residential single and three phase100, 200, 315, 400 and 630 amp - industrial /commercial
Download a copy of our procedure for the removal and replacement of company cut-out seals. Note: this only covers work undertaken by electrical contractors within the geographical areas covered by Scottish and Southern Electricity Networks. Procedure for the removal and replacement of company cut-out seals by electrical contractors
Only members of the following trade associations are permitted to remove cut-out seals:National Inspection council for Electrical Installation Contracting (NICEIC)Electrical Contractors' Association (ECA)Electrical Contractors' Association of Scotland (SELECT)National Association of Professional Inspectors and Testers (NAPIT)ELECSA (owned by the ECA)The arrangement has been approved on the understanding the trade associations will take formal disciplinary action against members who abuse this privilege.Every year the trade associations will provide us, free of charge, up-to-date copies of their membership rolls. Our revenue protection staff will carry out a random sample check to confirm our procedure is being followed.Trade Association members must phone us on 0800 048 3516 (England) 0800 048 3515 (Scotland), before removing company cut-out seals.Trade Association members must apply seals to the company cut-out when they have completed their work. Cut-out seals may be of the adhesive-label or plastic seal type and may be collected (and signed for) from the nearest Scottish and Southern Electricity Networks distribution depot. Stock number 03154701 (England); 03154730 (Scotland).We will reassess this arrangement if there is any evidence of abuse of this procedure.