It is a fundamental principle of the Wiring Regulations (BS7671) that all electrical installations must meet two basic criteria, first they must be safe and second, they must perform their intended function, ie. they must work. In the early days of electrical installations this was simple to achieve, because electrical installations were very simple in nature and safety requirements very basic by today's standards. Later, as the electrical industry grew, most electrical installation work was carried out by local electricity boards using time served tradesman, who were not hurried by the time and cost pressures experienced by modern electrical contractors. As a result, most installation work was performed to a high standard and therefore the checks carried out on this work was minimal. Fast forward to today and we see modern, highly complicated electrical installations, installed very quickly using teams of installers, many of whom will not be time served electricians. Add to this the increasing demands placed upon us to improve health and safety and the growing culture of claims and litigation. It is therefore essential in the modern world, that the safety and correct functioning of electrical installations is not just taken for granted, but is thoroughly proven by a rigorous process of inspection and testing. Out of this basic need has grown the art of inspection and testing, the subject on which this article is based.
To perform electrical installation testing the electrician will require an electrical installation tester like Seaward’s PowerTest 1557. The PowerTest 1557 is a multifunction tester, this means that Seaward have combined the individual test functions, such as; Earth Continuity, Insulation Resistance, Earth Fault loop and RCD testing into one instrument. Multifunction Testers or MFTs are now the industry standard for installation testing, but some electricians still like to use single function testers for specific jobs.