In-service safety inspection and testing of electrical equipment
In-service safety inspection and testing of electrical equipment
In-service safety inspection and testing of electrical equipment
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APPENDIX ATEST OF EARTHING CONTINUITY(Normative)A1 GENERALThe test <strong>of</strong> earthing continuity resistance shall be conducted to 2.3.3.1 during in-<strong>service</strong> <strong>testing</strong> <strong>of</strong>all Class I <strong>equipment</strong>. The test shall include flexing <strong>and</strong> straining at points <strong>of</strong> entry <strong>and</strong> clampingpoints by the application <strong>of</strong> reasonable combination <strong>of</strong> push/pull <strong>and</strong> rotary movements. This maydetect broken str<strong>and</strong>s or loose connections.A2 INSTRUMENTATIONFor 'in-<strong>service</strong>'<strong>testing</strong>, either <strong>of</strong> the following shall be used:(a)(b)An ohmmeter <strong>of</strong> accuracy Class 5 or better; orNOTE — Class 5 denotes an accuracy <strong>of</strong> 5 % full scale deflection.An <strong>equipment</strong> tester (portable appliance tester or PAT) with one or more <strong>of</strong> the following testcapabilities:(i)(ii)(iii)12 V maximum, test current in the range 100 to 200 mA;NOTE — This mode is commonly known as an 'earth continuity'test.12 V maximum, test current <strong>of</strong> 10 A The test duration is limited to the maximum timerequired for measurement;NOTE — This mode is commonly known as a 'routine test'.12 V maximum, at 1.5 times the rated current <strong>of</strong> the appliance or 25 A, whichever isthe greater. The test duration is limited to the maximum time required formeasurement. The use <strong>of</strong> this option is not recommended <strong>and</strong> caution should beexercised when considering its application to an item containing electroniccomponents.NOTE — This mode is commonly known as a 'type test'.A3 TEST CONDITIONSA3.1 Earthing continuity resistance shall be measured between any accessible earthed parts,including rotating metal parts, <strong>and</strong> the earth pin <strong>of</strong> the plug. The resistance shall not exceed 1 .A3.2 For cord sets, cord extension sets, portable outlet devices, <strong>and</strong> portable RCDs, theresistance between the earthing connections <strong>of</strong> the plug <strong>and</strong> outlet(s) shall be measured. Theresistance shall not exceed 1 .NOTE —(1) Figure A1 shows one method <strong>of</strong> <strong>testing</strong> resistance.(2) For the definition <strong>of</strong> accessible earthed parts, see 1.4.1.(3) Values measured (with the flexible cord included), are usually found to comply with a value <strong>of</strong>less than 0.5.(4) Some <strong>testing</strong> personnel remove the active <strong>and</strong> neutral pins <strong>of</strong> the test plug depicted in figureA2, to ensure the earth pin is sufficiently well gripped by the power board earth contacts.Page 19
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