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A Beginner’s Guide to Electrical Testing Sequence in the UK
The electrical testing sequence refers to the order in which different electrical equipment is tested in order to ensure its
safety.
The main reason for this is to prevent any potential risks or threats that may occur during the
testing process. This sequence is followed in order to ensure that all electrical equipment
meets the required standards.
The standard electrical testing sequence in the UK is as follows:
1- Initial Verification Testing Sequence
This verification is required if the electrical testing is for a new installation. It comprises
various steps, each of which should be passed in order to move to the next one.
Dead Testing
Before connecting a new electrical installation to the power supply, it is important to test the
installation to ensure that it is safe and compliant with local regulations.
This process, known as "dead testing," involves a series of tests designed to assess the various electrical
components of the installation.
There are four main tests that can be conducted on electrical circuits and equipment before
they are energized:
1. Continuity of Protective Conductors:
The objective of this test is to ensure that all current-carrying parts of the circuit are properly connected to the earthing system.
This includes verifying the integrity of any main and subsidiary earthing conductors, as well as any equipotential bonding conductors. A low impedance path to earth must be present so that any fault current will have an easy return path back to the source.
Any break or poor connection in the earthing system could allow a large voltage differential to develop between phase conductors and earth, posing a serious electrocution hazard to personnel coming into contact with both simultaneously.
2. Continuity of Ring Final Circuit Conductors:
This can be done by using a multimeter to test for continuity between the ends of the ring final circuit. If there is no continuity, this indicates that the ring final circuit is not functioning correctly and may need further testing & repair.
Watch below for a full demonstration of end to end & r1 + r2 of a ring circuit.
3. Insulation Resistance:
This test aims to measure how well an electrical insulation material resists the flow of electric current through it. The higher the insulation resistance, the better it is at performing its intended function - which is keeping electric current where it's supposed to be, i.e. flowing through conductors instead of through people!
The insulation resistance test can also reveal deterioration in insulation caused by age, moisture, or other factors, which could lead to premature failure and equipment downtime if left unchecked.
4. Electrical Separation:
Electrical separation is the process of separating the parts of an electrical circuit so that electricity can no longer flow through it.
5. Impedance of Floors and Walls:
This can be done by measuring the resistance of the surface to an electric current. The higher the impedance, the more resistant the
surface is to electrical current.
This information is important because it will help to determine how much current is required to safely dead test the surface.
6. Earth Electrode Resistance:
An earth electrode is a metal rod or plate that is driven into the ground in order to provide a low impedance path back to earth for fault
current in the event of an earth fault occurring in an electrical circuit.
The purpose of this test is to measure the resistance of the earth electrode and earthing system as a whole so that any faults can be rectified before energizing the circuit.
7. Polarity:
If you are testing a single-phase circuit & have completed r1 + r2 you have already tested polarity & can tick this box off.
On three-phase systems (and certain single-phase systems) in order to verify that the phase conductor connections are made correctly at all switchgear, distribution boards, and final subcircuits within the installation before energizing them. Incorrectly connected phase conductors could result in serious damage to equipment due to high currents flowing through them, so it's important that this test is conducted thoroughly and accurately.
Live Testing
Live testing refers to the testing of electrical products with the voltage connected. The main purpose of live testing is to check for potential problems that could occur when the product is used in a real-world environment.
1. When you are conducting a live test, the first thing you need to do is confirm the
correct earth electrode resistance. This can be done with an earth-fault loop tester or
the ammeter and voltmeter method.
2. Once you have confirmed the correct earth electrode resistance, you need to check
the earth-fault loop impedance. This is important to ensure that the Live testing is
conducted correctly and that there are no errors.
3. After you have confirmed the correct operation of the residual current devices, you
need to check the correct operation of switches and isolators. This is to ensure that
all components are working correctly and that there are no safety issues.
4. Finally, you should check the correct operation of the Live test itself. This includes
checking that all power is off, confirming that all wiring is secure and making sure that
all electrical equipment is safe to use. By following these steps, you can ensure that
your Live test is conducted safely and correctly.
2- Periodic Inspection Reports Sequence
Periodic Inspection Reports are an important part of electrical safety testing. They provide a record of the condition of an electrical installation at a particular point in time and can be used to help plan future maintenance or repair work. The main purpose of a periodic
inspection report is to identify any potential hazards so that they can be rectified before they cause any harm. The reports are also useful for landlords, who need to ensure that their properties are safe and fit for habitation.
Periodic inspection reports usually follow a standard format, which includes a list of all the electrical circuits in the property, along with an assessment of their condition. The report will also identify any recommended remedial work, such as replacing damaged wiring or fitting new circuit breakers. In some cases, the landlord may be advised to have the property rewired completely. However, this should only be done by a qualified electrician and should not be attempted by the tenant themselves.