BS EN 62052-11:2003 – Electricity metering equipment (AC) — General requirements, tests and test conditions — Part 11: Metering equipment

5.4 Terminals – Terminal block(s) – Protective earth terminal Terminals may be grouped in (a) terminal block(s) having adequate insulating properties and mechanical strength. In order to satisfy such requirements when choosing insulating materials for the terminal block(s), adequate testing of materials shall be taken into account. The material of which the terminal block is made shall be capable of passing the tests given in ISO 75-2 for a temperature of 1 35 °C and a pressure of 1 ,8 MPa (method A). The holes in the insulating material which form an extension of the terminal holes shall be of sufficient size to also accommodate the insulation of the conductors. The manner of fixing the conductors to the terminals shall ensure adequate and durable contact such that there is no risk of loosening or undue heating. Screw connections transmitting contact force and screw fixings which may be loosened and tightened several times during the life of the meter shall screw into a metal nut.
All parts of each terminal shall be such that the risk of corrosion resulting from contact with any other metal part is minimized.
Electrical connections shall be so designed that contact pressure is not transmitted through insulating material. For current circuits, the voltage is considered to be the same as for the related voltage circuit. Terminals with different potentials which are grouped close together shall be protected against accidental short-circuiting. Protection may be obtained by insulating barriers. Terminals of one current circuit are considered to be at the same potential.
The terminals, the conductor fixing screws, or the external or internal conductors shall not be liable to come into contact with metal terminal covers. The protective earth terminal, if any:
a) shall be electrically bonded to the accessible metal parts;
b) should, if possible, form part of the meter base;
c) should preferably be located adjacent to its terminal block;
d) shall accommodate a conductor having a cross-section at least equivalent to the main current conductors but with a lower limit of 6 mm 2 and an upper limit of 1 6 mm 2 (these dimensions apply only when copper conductors are used); e) shall be clearly identified by the graphical symbol IEC 6041 7-501 9: Protective earth (ground). After installation, it shall not be possible to loosen the protective earth terminal without the use of a tool.
5.5 Terminal cover(s) The terminals of a meter, if grouped in a terminal block and if not protected by any other means, shall have a separate cover which can be sealed independently of the meter cover. The terminal cover shall enclose the actual terminals, the conductor fixing screws and, unless otherwise specified, a suitable length of the external conductors and their insulation.
BS EN 62052-11:2003 – Electricity metering equipment (AC) — General requirements, tests and test conditions — Part 11: Metering equipment