Testing electrical installations

Network conflicts Electrical installation Cable connections Electrical testing Uninterrupted power supplies Input/output... 

A factory acceptance test (FAT) should be performed. The report should cover at least a check against Customer Order for completeness, visual check for appearance and identification, the record of serial numbers of filters, dimensional check, electrical installation and safety check, functional check, including operation of interlocks and alarms and documentation 216 217... 

Similarly, all electrical installations (transformers, metering panel, incoming high tension supply, etc.) are to be thoroughly cleaned, overhauled, and offered for inspection. The instmctions from electrical inspector shall also be complied with, and aU facilities tested. 

If the stated company procedure is to use battery drills whenever possible, or 110 V drills when this is not possible, and to never use 230V drills, then this again will reduce the risk. If a policy such as this is written down in the company safety policy statement, then you can simply refer to the appropriate section of the safety policy statement and the level of risk will be low. (Note PAT testing is described in Advanced Electrical Installation Work.)... 

Electrical installation circuits usually carry in excess of 1A and often camy hundreds of amperes. Electronic circuits operate in the milliampere or even microampere range. The test instruments used on electronic circuits must have a high impedance so that they do not damage the circuit when connected to take... 

The use of an insulation resistance test as described by the lET Regulations must be avoided with any electronic equipment. The working voltage of this instrument can cause total devastation to modern electronic equipment. When carrying out an insulation resistance test as part of the prescribed series of tests for an electrical installation, all electronic equipment must first be disconnected or damage will result. 

Because of the mobile nature of caravans it is recommended that the electrical installation be tested and inspected at intervals considered appropriate, preferably not less than once every three years and annually if the caravan is used frequently (lET Regulation 721.514.1). 

The electrical contractor is charged with a responsibility to carry out a number of tests on an electrical installation and electrical equipment. The individual tests are dealt with in Part 6 of the lET Regulations and described later in this chapter. 

In this chapter City Guilds asks us once again to look at a safe isolation procedure as a preparation for inspecting and testing an electrical installation. 

If you are confident that you remember this topic from Chapter 1, go straight on to the next section, Inspection and testing an electrical installation . 

There is an increased use of electronic devices in electrical installation work for example, in dimmer switches and ignitor circuits of discharge lamps. These devices should be temporarily disconnected so that they are not damaged by the test voltage of, for example, the insulation resistance test (IET Regulation 612.3). 

The test instruments and test leads used by the electrician for testing an electrical installation must meet all the requirements of the relevant regulations. The HSE has published guidance note GS 38 for test equipment used by electricians. The IET Regulations (BS 7671) also specify the test voltage or current required to carry out particular tests satisfactorily. All test equipment must be chosen to comply with the relevant parts of BS EN 61557. All testing must, therefore, be carried out using an approved test instrument if the test results are to be valid. The test instrument must also carry a calibration certificate, otherwise the recorded results may be void. Calibration certificates usually last for a year. Test instruments must, therefore, be tested and recalibrated each year by an approved supplier. This will maintain the accuracy of the instrument to an acceptable level, usually within 2% of the true value. 

The test instruments and test leads used by the electrician for testing an electrical installation must meet all the requirements of the relevant regulations. 

To measure accurately the resistance of the conductors in an electrical installation, we must use an instrument which is capable of producing an open-circuit voltage of between 4 and 24V a.c. or d.c., and delivering a short-circuit current of not less than 200mA (lET Regulation 612.2.1). The functions of continuity testing and insulation resistance testing are usually combined in one test instrument. 

All installations must be periodically tested and inspected, and for this purpose an Electrical Installation Condition Report should be issued (lET Regulation 631.2). 

The maximum inspection and re-test period for a domestic electrical installation is ... 

Use bullet points to state three reasons for testing a new electrical installation. 

State the first five tests to be carried out on a new electrical installation following a satisfactory inspection . For each test ... 

The test instruments and test /eads used by the electrician for testing an electrical installation must meet all the requirements of the relevant regulations. All testing must, therefore, be carried out using an approved test instrument if the test results are to be valid. The test instrument must also carry a calibration certificate othenvise the recorded results may be void. 

Because of the mobile nature of caravans it is recommended that the electrical installation be tested and inspected at intervals considered... 

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