EN 50191:2010 – Erection and operation of electrical test equipment

EN 50191:2010 - Erection and operation of electrical test equipment Test assembly
The test assembly shall be so arranged and designed that the protection against direct contact is secured by insulation of live parts, covers, enclosures, obstacles or safe distances. A safe distance is ensured, when the person carrying out the tests cannot reach the prohibition zone with parts of his/her body or tools. Safety can also be satisfied by means of a two-hand control device or the use of two safety test probes to apply the test voltage. Test leads with full protection against direct contact shall be used. Two-hand control devices shall comply with EN 574:1996 + A1:2008, Type II or IIIB. Where several persons are involved in a test, a two-hand control device shall be provided for each person of the test personnel and which are so connected that all the two hand controls are required to be operated before the test supplies can be energised.
Safety test probes shall have the adequate insulation level for the applied test voltage. No clamping devices shall be permitted for this purpose.
In case of measuring instruments and auxiliary appliances of protection Class I EN 61140 (e.g. cathode ray oscilloscope, sine wave generator), where the protective conductor is interrupted to facilitate testing, e.g. because the enclosure has to be isolated from earth potential, the appliance shall be supplied from an isolating transformer in accordance with EN 61558 series.
If a circuit and/or the enclosure of a measuring instrument or an auxiliary appliance designed for mains connection is connected to live parts of the test assembly which can carry voltage to earth, then the internal insulation of the supplying isolating transformer shall be rated at least for this voltage.
An effective protective measure for fault protection (protection against indirect contact) shall be provided (see HD 60364-4-41,Clause 411.3).
The test object shall be isolated from earth. If this is technically not possible e.g. due to the weight of the test object, than the test assembly shall be so designed and arranged in order to prevent the transfer of voltage to extraneous conductive parts.
Test table boards shall be made of insulating materials. Prohibition zone
The boundary of the prohibition zone shall be determined in accordance with Table A.2 and is dependent on the test voltage.
In case of voltages up to 1 000 V, the surface of the live part is considered to be the boundary of the prohibition zone. In case of voltages exceeding 1 kV, reaching the prohibition zone is considered equal to touching live parts. Barriers, test area
Test areas shall be separated from work areas and passageways. The barriers shall be so designed as to
– prevent access to the test area by persons other than the test persons,
– prevent persons, other than the test persons, from reaching the prohibition zone,
– prevent persons outside the barrier from reaching the operating devices of test installations which are located inside the barrier.

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