The Electricity Supply Regulations

The Electricity Supply Regulations forhid electricity supply authorities to connect electric lines and apparatus to the supply system unless their insulation is capable of withstanding the tests prescribed by the appropriate British Standards. 

Some forms of electrical incident, such as the explosive failure of an item of high voltage switchgear belonging to an electricity distribution company, have to be reported to the DTFs engineering inspectorate. This reporting duty is covered by the Electricity Supply Regulations, as explained in Chapter 8. 

The DTI s engineering inspectors enforce the Electricity Supply Regulations. 

In caravan parks, the distribution system should comply with the relevant parts of the Electricity Supply Regulations 1988 as well as with the Division Two requirements. Regulation 608-13-05 could perhaps have been improved by indicating that for TN-S supplies the supply company will normally provide an earthing facility, but for TN-C-S (PME) and TT supplies an earth electrode has to be installed by the occupier. The section requires the supply socket outlets to have sensitive RCD protection complying with subsection 412-06, as for the caravan installations, so that in the event of an earth fault in a caravan both RCDs should operate. To avoid more than the faulty installation supply being disconnected, grouping should be avoided and an RCD provided for each socket outlet. 

Section 5 Earthing is about the earthing methods in the several supply systems and the requirements of the Electricity Supply Regulations. Section 5.2 deals with the problems of earth electrodes where the consumer has to provide his own earth. 

A normal modern intake into a house comprises a CNE concentric service cable terminating in a plastic sealing box. The supply company provides an earthing terminal connected to the cable sheath, which is the CNE conductor, and a cut-out consisting usually of a 60 A or 100 A BS 1361 fuse. The meter tails are generally PVC insulated and sheathed conductors. The Electricity Supply Regulations require them to be marked for polarity. Quite... 

Note that the Electricity Supply Regulations require the earthing conductor to comply with the table in Regulation 7, which means a minimum cross sectional area of 10 mm if the service cable does not exceed 35 mm. This size also applies to the main equipotential bonding conductors. 

Check the position of the meter. The Electricity Supply Regulations require it to be installed in the consumer s premises unless it is more reasonable for it to be located elsewhere, in which case it should be accessible to the consumer. This is more likely to occur in blocks of flats and housing in multiple occupation. In such premises the supply authority may bring in only one service cable on to a busbar and then feed each tenant via cables in conduit or sometimes in MIMS cable. The latter is not a good choice because the insulation is hygroscopic and if the end seals fail, the cable can break down. It may also fail if subject to HV transients, so such cables should be fitted with suppressors. If the conduit or sheath of the MIMS cable is used as the earthing conductor, check that the connections are satisfactory and of low resistance and any joints in the conduit provide adequate continuity. 

The Electricity at Work Regulations are very specific in describing the procedure to be used for isolation of the electrical supply. Regulation 12(1) tells us that isolation means the disconnection and separation of the electrical equipment from every source of electrical energy in such a way that this disconnection and separation is secure. Regulation 4(3) tells us that we must also prove the conductors dead before work commences and that the test instrument used for this purpose must itself be proved immediately before, and immediately after. 

The Electricity Safety, Quality and Continuity Regulations 2002 (formerly Electricity Supply Regulations 1989)... 

Stand-alone systems are not connected to the electricity supply system and are therefore exempt from much of BS 7671, the lET Regulations. However, Regulation 134.1.1 good workmanship by competent persons and proper materials shall be... 

A voltage regulator should be used to isolate the instrument from voltage fluctuations, and the electric supply should be latched to avoid uncontrolled powering up of the apparatus following a power failure. 

The intention of Regulation 20 is to ensure that when a coneentration of firedamp in excess of 1.25% by volume is detected, the electricity supply, at the location, is cut off to equipment which is not explosion-protected before the concentration reaches the lower explosive limit and becomes a hazard. 

The Regulations are intended to ensure the reliability and quality of the electricity supply and to safeguard the public, livestock and domestic animals... 

The technical content of the new Regulations concerning matters such as earthing and protection tends to match that of the 1988 Regulations, although it is written in a much less prescriptive and detailed fashion. The substantial changes cover the allocation of duties to those entities now operating in the electricity supply market. From the perspective of safety,... 

DTI engineering inspectors the notification of specified events (such as death caused by systems covered by the Regulations) and certain interruptions of supply exemptions from the Regulations breaches and offences and the revocation of the previous Electricity Supply Regulations and the Electricity (Overhead Lines) Regulations 1970. 

Although the electricity supply companies have converted a substantial number of TT systems to TN-C-S systems, some TT systems are still in use, mostly in rural areas where it is often difficult or impracticable to obtain and maintain a low earth loop impedance. In these cases, the overcurrent protection should be supplemented by RCD protection as required in Regulations 413-02-18 to 20 and 471-08-06. 

There may well be considerable overlap between the responsibilities of the utility companies, the insurer and the authorities. For example, the electricity supply company may be the de facto or even the de jure authority for the plant electrical installation. In some countries the enforcement of regulations concerning boilers and lifting devices may in effect be left to the insurer. For this reason it may be advantageous for the EPCM contractor s authorities engineer also to be responsible for liaison with the insurer and the utility companies. 

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