The objectives of the first phase of the research, which is now complete, were to determine the following:
	The mechanisms by which RCDs fail to operate correctly after prolonged periods of inactivity in domestic environments.
	Provide an opinion on the relevance of these mechanisms for the RCDs currently on sale in the UK.
	Provide recommendations for an RCD test programme to be conducted in the second phase of the research.

From the first phase it was concluded that:
	Previous research published in Italy indicated that electromechanical RCDs had an average failure rate of 7.1%. However, if the RCDs were operated regularly by means of the integral test button, this figure fell to 2.8%, indicating that RCD reliability improved if they had been operated regularly.
	From the available evidence, the primary mode of failure on electro-mechanical RCDs was ingress of fine particles of dust and moisture causing the moving components to stick or to operate slower than intended.
	Whilst manufacturers of electronic RCDs claimed that their products are more reliable than electro-mechanical RCDs, very little evidence to support this was found. Previous research in the USA suggests that the reliability of electronic RCDs may be similar to that of electro-mechanical RCDs.

t ERA’s expert engineers are conducting comprehensive RCD research, which includes on-site testing in domestic properties.

The results of the first phase of ERA's research have attracted a great deal of interest. The full report can be downloaded from the Electrical Safety Council's website (www.electricalsafetycouncil.org.uk).

The second phase is ongoing and covers RCD testing in domestic properties together with failure analysis on suspect RCDs. To ensure that the results of the field testing are statistically valid, tests are being conducted on a relatively large number of RCDs in premises where their
age and operating history is known and where there are significant numbers of devices of the same type and age.

For more information contact: bob.dean@era.co.uk or visit Engineering Consultancy Services.

About ERA Technology
ERA Technology works at the leading edge of many advanced technologies. The business was founded in 1920 and today provides specialist, high value-added, technology-based services including design and development, testing, assessment and expert advice.

The company has built an international reputation for technical expertise through constant innovation at the leading edge of technology. ERA's services reduce technical and commercial risk, improve the operational performance of engineering infrastructure assets, and enhance the competitiveness of products and systems.

ERA Technology is a part of Cobham plc.

For more information, please contact: marketing@era.co.uk