IEC 60990 Ed. 3.0 b:2016

Methods of measurement of touch current and protective conductor current

IEC 60990:2016 RLV contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.

IEC 60990:2016 defines measurement methods for d.c. or a.c. current of sinusoidal or non-sinusoidal waveform, which could flow through the human body, and current flowing through a protective conductor.

The measuring methods recommended for TOUCH CURRENT are based upon the possible effects of current flowing through a human body. In this standard, measurements of current through networks representing the impedance of the human body are referred to as measurements of TOUCH CURRENT. These networks are not necessarily valid for the bodies of animals.

The specification or implication of specific limit values is not within the scope of this standard. IEC TS 60479 series provides information regarding the effects of current passing through the human body from which limit values may be derived. This standard is applicable to all classes of EQUIPMENT, according to IEC 61140.

The methods of measurement in this standard are not intended to be used for TOUCH CURRENTS having less than 1 s duration, patient currents as defined in IEC 60601-1, a.c. at frequencies below 15 Hz, and currents above those chosen for ELECTRIC BURN limits.

This third edition cancels and replaces the second edition published in 1999. It constitutes a technical revision. The principal changes in this edition as compared with the second edition are as follows:

• the effects names have been updated to reflect increased understanding of the range of effects and is in concert with present usage;
• the conditions of use invoking a GRIPPABLE PART have been reduced in the application of the requirements based upon the current understanding of this effect;
• the references to ISO 10012-1, which has been replaced by management standard of the same number, have been replaced with explanatory text, where needed to maintain the sense of the document;
• former informative Annex H (GRIPPABLE PART) has been deleted from this update as it does not properly represent the full set of conditions under which immobilization can occur. A new informative Annex H (Analysis of frequency filtered touch current circuits measurement) has been added and the Bibliography (formerly Annex M) has been updated with additional references for completeness.

This basic safety publication is primarily intended for use by technical committees in the preparation of standards in accordance with the principles laid down in IEC Guide 104 and ISO/IEC Guide 51. It is not intended for use by manufacturers or certification bodies independent of product standards.

Key words: Touch Current, Protective Conductor Current, Current Flow