Talk:Definition of standardised earthing schemes/Archive 1

Is the following sentence related to TN-C system  correct with or without "OR"?

This system is not permitted for conductors of less than 10 mm2 OR for portable equipment.

IEC60343-5-54 PEN

To be precise, the IEC60364 states:

411.4.3 In fixed installations, a single conductor may serve both as a protective conductor and as a neutral conductor (PEN conductor) provided that the requirements of 543.4 of IEC 60364-5-54 are satisfied. No switching or isolating device shall be inserted in the PEN conductor.

543.4.1 A PEN conductor may only be used in fixed electrical installations and, for mechanical reasons, shall have a cross-sectional area not less than 10 mm2 in copper or 16 mm² in aluminium.

So TNC can not be used for portable equipment, and when used for fixed installation PEN shall have S>=10mm2 If active conductors' size is lower, it's usually cheaper to go to TNS. --Mathieu GUILLOT 08:42, 30 April 2010 (UTC)

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In that case sentence related to TN-S system should be: The TN-S system (5 wires) is obligatory for circuits with cross-sectional areas less than 10 mm2 OR for portable equipment.