Our Voltimum Experts answer your questions on a daily basis in our Technical Expertise area. This one, about the use of mA clamp meters for determination of insulation resistance, is answered by NAPIT:
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| A clamp meter by Fluke. |
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Question: Is there any guidance or regulation in existence regarding the use of milliamp and microamp clamp meters for the determination of insulation resistance in existing installations?
Answer: The requirements for insulation testing are given in Regulation 713-04 of BS 7671 (16th Edition). This is a high voltage, 'dead' test. In referring to the required tests, Regulation 713-01-01 states: 'Other methods are not precluded provided they give valid results'.
New technologies exist which enable energised electrical installations to be regularly monitored. These methods would include, for example, the monitoring of thermal radiation by means of an infrared camera. From the information which you have supplied, you appear to be referring to the use of leakage clamp meters which can be used to monitor insulation resistance. Manufacturers guidance must be carefully followed.
This method can fulfil the requirements of Regulation 732-01-02 which permits 'an adequate regime of continuous monitoring and maintenance of the installation by skilled persons' to replace the normal periodic inspection and testing. The installation must be under effective supervision in normal use. Page 64 of IEE Guidance Note 3, Inspection and Testing, gives further guidance.
And Voltimum UK managing editor James Hunt says: The 17th Edition of the IEE Wiring Regulations has just been published, so this answer (with reference to the 16th Edition) needs to be seen in that light. Electrical contractors and installers should purchase the 17th Edition and/or undertake suitable training. Note that full implementation of the 17th Edition will be on July 1st. Over the next six-months, the 16th Edition will be phased out and 17th Edition will be implemented. Within this period, installations can comply with either. After 2nd July 2008, installations should comply only with the 17th Edition. For longer-term projects with overlap, the client concerned must be made aware of the situation.
To see many more Q & A in Voltimum UK's Experts Area, please click on the link: http://www.voltimum.co.uk/consult.php?universe=consult.index.questions
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Related contacts
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NAPIT (Part P Office)
4th Floor, Mill 3,
Pleasley Vale Business Park
Mansfield, Nottinghamshire NG19 8RL
Tel: 0870 4441392
Fax: 0870 4441427
Email: info@napit.org.uk
Web: www.napit.org.uk |
NAPIT
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| Source: N.A.P.I.T. & James Hunt |
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