Periodic Inspection Testing Procedures

by Steve on October 1, 2011

This article gives an overview of the range of recommended electrical testing procedures required for Periodic Inspections and Condition Reporting (EICR). You should refer to BS7671 or Guidance Note 3 for a full list of the requirements for Inspection and Testing.

Important
This article is an overview of the requirements for electrical testing and inspection. BS7671 and the Guidance Notes are definitive and should always be consulted to verify information obtained from this website.

Safety Concerns

Electrical testing involves an element of risk and the IEE Regulations include the requirements for Health and Safety regarding Competent Persons and Safe Isolation. Anyone carrying out inspection and testing has a duty to ensure the safety of themselves and others. A knowledge of the requirements of the wiring regulations and the correct testing procedures is essential.

Testing and inspecting of electrical circuits will require normally ‘live parts’ to be exposed by the inspector.  Regulation 611 requires that testing and inspection procedures should be undertaken with the relevant circuits disconnected from the supply.  Any work must be carried out with regard to compliance with the Electricity at Work Regulations which refers to working practices and the dangers of any work or activity near ‘live’ conductors.

Test Selection

The person undertaking the testing can decide which of the tests are appropriate and the order in which they are carried out. They should use their knowledge and experience of the installation and consult existing records where available.

Sample Tests

The percentage of sampling is at the discretion of the tester. A percentage of less than 10% is not advised by Guidance Note 3.

Earth Fault Loop Impedance Tests

Test at the origin of the installation (Ze) with bonding temporarily disconnected, Distribution boards (Zdb) and Sockets & extremities of Radial circuits (Zs).

Notes
The Protective and Equipotential Bonding conductors must NOT be disconnected whilst the supply to an installation is energized. This is because if a fault is already present or should occur the exposed and extraneous conductive parts of the installation could become live.

After testing Ze at the origin, re-connecting the bonding conductors and re-energizing the system, it can save time to carry out a PSCC/PFC test at the same position.

Earth Electrode Resistance Tests

Where applicable, electrode resistance tests may be required. Guidance Note 3 states that each earth rod or group of rods should be tested separately, with the test links removed and with the installation isolated from the supply.

Continuity of CPC and Bonding Tests

Test between the earth terminal of distribution boards to the exposed conductive parts of socket outlets earth connections and extremeties of circuits (R2)
Continuity of bonding and supplementary conductors- Less than 0.05Ω.

Notes
Guidance Note 3 states that Earth Fault Loop impedance test may be used to confirm the continuity of protective conductors at sockets and at accessible exposed conductive parts such as metal switch plates and the metallic casings of appliances. Earth Loop Test instruments which don’t require a neutral connection are ideal for verifying earth continuity, especially at light switches.
Some RCDs may be tripped by an Earth Loop Test. In these and other cases earth continuity can be checked by an R2 test (Test Method 2).

Test Methods 1 (R1+R2)  and 2 (R2), as described in Guidance Note 3, are alternative ways of testing the continuity of protective conductors including main and supplementary equipotential bonding.

Periodic Inspections- ‘Accessibility’ for these earth tests may be considered to be within 3 m from from where
a person can stand.

Ring main Continuity Tests

Guidance Note 3 states that where there are proper records of previous tests and there have been no additions or alterations, a ring main continuity test may not be necessary. Despite this, it is highly recommended to check end to end continuity of ring conductors to verify the integrity of connections at sockets and joints when carrying out Periodics and EICRs.

Insulation Resistance Tests

Insulation test between live/neutral, live/earth & neutral/earth. Where electronic or sensitive equipment  may be in circuit, test to earth with live and neutral connected together.
Also test at main and sub-main distribution boards, with final circuit distribution boards switched off.

Table 61 of BS 7671 requires a minimum insulation resistance of 1 MΩ, however low resistances of less than 2 MΩ will require further investigation.

Notes
For insulation testing some devices which have functional earth connections (Electronics/Computers/SPDs)may require disconnecting to prevent damage and influencing test results. This test may not be necessary where there are records of previous tests and there is no evidence of alteration or additions.

Polarity

Test at the origin of the installation, distribution boards, sockets and at the extremity of each radial circuits.

Guidance Note 3 requires that:

  • Polarity is correct at the meter and distribution board
  • Every fuse and single-pole control and protective device is connected in the line conductors only
  • Conductors are correctly connected to socket-outlets and accessories
  • Except for E14 and E27 lampholders to BS EN 60238, centre-contact bayonet and Edison screw lampholders have their outer or screw contacts connected to the neutral conductor
  • All multi-pole devices are correctly installed.

RCD Tests
Tests for trip times of RCD devices (30mA = 300ms max) followed by the operation of the functional test button.

Guidance

Guidance Note 3 is an indispensable reference source for anyone carrying out the inspection and testing of electrical installations. Sections include: General requirements, Testing Procedures for Initial Verification and Periodic Inspecting, Test Instruments and Sample Forms. References include Maximum Permissible Earth Fault Impedences and Tables of R1+R2 values for cables (similar to the On-Site Guide).

Training

If you need to get trained up and qualified for electrical inspection and testing here are the related C&G courses.

C&G 2392 – Fundamental Inspection & Testing- 4 day course

C&G 2391-10 – Advanced Inspection & Testing- 4 day course

C&G 2391-20 – Design & Verification

C&G 2399-01, C&G 2399-11 and C&G 2399-12
Installing & Testing Domestic Photovoltaic (PV) Systems Certificate.
This is for electricians wishing to self-certify solar PV installations through the NIC’s MCS Installer Scheme. 4 day course

Be sure to check out your local colleges and training centres for more info and exact pricing of their specific City & Guilds electrical inspection and testing training courses



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