Electrical Testing Procedures
By law, electrical equipment in the workplace has to be maintained to prevent danger and reduce the risk of injury and damage. Failure to comply is a criminal offence and can result in fines and imprisonment.
To ensure compliance with statutory regulations, electrical testing procedures and inspections should be carried out by experienced, qualified electricians with suitable equipment on all new installations and alterations, and on a periodic basis on existing equipment.
While the frequency of testing is determined by factors such as the equipment, the environment and the results of previous checks, standards and sequence for electrical testing procedures need to be followed correctly to ensure effectiveness of the exercise.
New installation completion or alterations
“Every installation shall, during erection and on completion before being put into service be inspected and tested to verify, so far as reasonably practicable, that the requirements of the regulations have been met.” BS 7671, Regulation 610.1
An initial verification inspection and testing procedure must be completed on all new installations and alterations to certify they are safe and compliant. Certification can only be issued by a competent person who has tested, inspected and verified the installation.
The electrical testing procedure should be followed by the completion of an Electrical Installation Certificate. Alteration of an existing electrical installation requires a Minor Electrical Work Certificate to be completed.
Periodic inspection and testing
“Where required, periodic inspection and testing of every electrical installation shall be carried out in accordance with regulations 621.2 to 621.5 in order to determine as far as reasonably practicable, whether the installation is in a satisfactory condition for continued service“. BS 7671, Regulation 621.1
For existing electrical installations, a periodic inspection and testing procedure needs to be completed.
The electrical testing procedure of existing electrical installations should also include visual examination and be followed by the completion of a periodic inspection report.
The engineer who performed the test should also identify any remedial work necessary to fix faults, damage or hazards under the following categories:
- Code one – for urgent attention
- Code two – for improvement
- Code three – for further investigation
- Code four – does not comply with current BS7671 standards
What Electrical Testing Procedures are used?
Electrical testing procedures apply to both initial verification and periodic inspection and include both dead testing and live testing procedures.
Each circuit must be tested. Testing procedures comprise dead and live testing and visual inspections and will require knowledge and experience of the relevant sequence of tests to be followed in respect of both new installations and periodic inspections.
An experienced and qualified electrician will be able to assess and advise on the most appropriate testing sequence.
Electrical testing procedures should comprise:
Protective Conductors Continuity including Bonding Conductors
Every protective conductor, including the earthing conductor, main and supplementary bonding conductors, should be tested to verify that the conductors are electrically sound and correctly connected. An insulation resistance/continuity tester or multi tester with the LOW resistance range selected should be used to carry out this test.
Between the earth terminal of distribution boards to the following exposed conductive parts
- Socket Outlet earth connections
- Accessible exposed conductive parts of current using equipment and accessories
Ring Circuit Continuity
A test is required to verify the continuity of each conductor including the circuit protective conductor of every ring final circuit. The test results should establish that the ring is complete and has not been interconnected. An insulation resistance/continuity tester or multi tester with the LOW resistance range selected should be used to carry out this test.
Where there are proper records of previous tests, this test may not be necessary. This test should be carried out where inspection/documentation indicate that there may have been changes made to the final ring circuit.
Insulation resistance testing
These tests are to verify that for compliance with BS7671 the insulation of conductors and electrical accessories and equipment is satisfactory and that the live conductors or protective conductors are not short circuited, or show a low insulation resistance. These tests will be carried out between each live conductor and cpc and phase to phase for 3 phase circuits.
If tests are to be made – between live conductors, with phases and neutral connected together, and earth at all final distribution boards. At main and sub main distribution panels, with final circuit distribution boards isolated from the mains.
An insulation resistance/continuity tester or multi tester with the HIGH resistance range selected should be used to carry out this test.
Results obtained should be compared with the readings given in Table 61 in BS7671.
Insulation of non conducting floors and walls
Where protection against indirect contact is provided by a non conducting location, the tests as directed in 413-04 are to be implemented.
The polarity of all circuits must be verified at the origin of the installation, distribution boards, accessible socket outlets, extremity of radial circuit, before connection to the supply and in the case of lighting circuits, ensure that all fuses and single pole switches are connected in the phase conductor. An insulation resistance/continuity tester or multi tester with the LOW resistance range selected should be used to carry out this test.
Earth Electrode Resistance
Test Method 1 uses an Earth Electrode Resistance Tester. Test Method 2 uses an EFLI meter. When measuring earth electrode resistance to Earth (Ra) where low values are required, as in the earthing of the neutral point of a transformer or generator, test method 1 should be used. If the electrode is being used in conjunction with an RCD, test method 2 may be applied as an alternative to test method 1. Test each earth rod or group of rods separately, with the test links removed, and with the installation isolated from the supply source.
Earth fault loop impedance testing
At origin of the installation, distribution boards, accessible socket outlets, extremity of radial circuit. EFLI may be determined by either direct measurement or calculation based upon readings obtained for Ze and R1+R2. The tests must be completed at the points specified in BS7671. An EFLI meter or multi tester may be used with the LOW impedance range selected.
Functional Tests RCD’s, Circuit Breakers, Isolators and all Switching Devices
Tests as required by Regulation 713-13-01, followed by the operation of the functional test button. Manual tests to prove that the devices disconnect the supply. Where means are provided in accordance with the regulations for isolation and switching, they should be operated to verify their effectiveness and checked to ensure adequate and correct labelling. Easy access to said devices must be maintained and effective operation must not be impaired.
Site applied insulation
Site applied insulation is carried out ONLY where the insulation is applied DURING erection. They are not applied when type tested switch-gear is assembled on site. In most cases this test will be not applicable. The tests involve the use of high voltages and great care is necessary to avoid danger.
Do you need help with electrical testing procedures?
Electrical safety is a mandatory requirement. Effective use of electrical testing procedures can ensure compliance and safety, with minimal disruption to your operations. For help with your electrical testing, contact Emelec’s team of experienced electrical engineers.
This article is for informational purposes only and does not constitute direct advice.