Code of Practice for the Inspection and Testing of Portable Electrical Equipment - "PAT Testing"

The Health and Safety Executive states that about one quarter of all reportable electrical accidents at work involve portable electrical equipment, and there are about five fatalities each year involving such equipment.

The majority of these accidents are entirely avoidable, and many are due to very obvious faults in equipment.

The purpose of these inspections and tests is to check the electrical safety of all portable electrical equipment regularly so that dangerous faults can be corrected before they cause any injury.

Authorised Testers will be appointed under the code of practice, and will be given a written authorisation which clearly defines the extent of the electrical inspections and tests that they are authorised to do.

No Authorised Tester will be expected to carry out tests on types of equipment with which they are not familiar, or be expected to make judgements on matters beyond their training or experience.

Except for replacing fuses and mains plugs, any repair work required on equipment as a result of these inspections and tests should not be undertaken by Authorised Testers, unless they have the required specialist electrical knowledge and experience.

The initials of an Authorised Tester on a test label signify only that the item of equipment so identified was electrically safe in term of the inspection carried out on the stated date.

The Authorised Tester is not certifying the equipment to be safe after the quoted date.

Authorised Testers may seek further training or advice from the University Safety Office (ext 4100).


1. All portable electrical equipment in the University is subject to regular inspection and tests as in the attached schedule, with the exception of:

(a) Rented or hired equipment or equipment on loan. No electrical tests should be made, but a visual inspection of the mains lead, mains plug, and integrity of protective casing must be made, and any defects which can not be easily corrected should be reported to the owner of the equipment.

(b) Personal domestic equipment used by students within their Halls of Residence is exempted, but students are advised to maintain this equipment in a safe condition for their own protection.

(c) Contractor's equipment. The safety of this equipment is the responsibility of the contractor.

(d) Computers, electronic typewriters, etc, should not be tested with the PAT or PAC testers, as the tests could damage the equipment. The mains lead and plug should be inspected, and the outer casing should be inspected for any damage.

2. Inspection and testing will only be carried out by people nominated and authorised as Authorised Testers.

Check List for inspections and tests

1. Check the electrical rating plate or Label

  • Voltage - should be 230 to 250 Vac (or)
  • Power Rating - should be less than 3 KW
  • Protection Class - should be class I or Class II (may be IIA or IIB)
  • If Class II, the double insulation symbol must be shown.

2. Can the PAT or PAC testers be used on this equipment? (See Requirements sections a, c & d).

3. Visual inspection


Disconnect the equipment from the mains supply.


Is the length of mains lead suitable and safe for the equipment and the way it is used?


Is the mains lead firmly connected to the equipment with a rubber or plastic bush if it passes through a metal panel? (Try pulling, pushing and rotating the mains lead).


Are there any kinks or knots in the mains lead?


Are there any taped joins in the mains lead?


Is the outer insulation, including braid if present, intact and undamaged on the whole length of the mains lead?


Is the outside of the mains plug cracked, damaged, or very dirty?

Following this inspection, replace any suspect mains plugs and arrange for any faulty mains leads to be replaced.

4. Internal check on mains plug


Is the inside of the plug, and cover, free from cracks, burns, or other damage?


Is the cable clamp intact and firmly gripping the outer sheath of the mains lead?


Are the cable ends the right length, fully insulated almost to the plug terminals, and firmly attached to the correct terminals in the plug? Always double-check this.


Is the fuse correctly rated for the equipment?

Following this inspection replace the fuse or plug if necessary.

5. Electrical safety tests

These tests will use the PAT or PAC test instruments where appropriate.

Warning Do not touch the equipment being tested while the test is being carried out.

5.1 Does the equipment have a 3-core mains lead (Class I) or a 2-core mains lead (Class II)?
5.2 Class I (earthed) equipment, with 3-core mains lead

Using the PAT tester

Earth Bond Test - with clip lead connected to metal case of equipment under test.
Reading should be in green band or less than 0.1 ohm (0.3 ohm in special cases, see note iii).
Insulation Test - disconnect dip lead.
Equipment mains switch must be ON.
Reading should be in green band.

No further tests should be made.


Using the PAC checker

Connect clip lead to metal case of equipment under test.
Equipment mains switch must be ON.
Press test button and hold until two lights show on PAC checker.
Both lights should show PASS.

No further tests can be made.

5.3 Class II (double insulated) equipment, with 2-core mains lead.
  5.3.1 Check that the manufacturer's double insulation symbol is present.
  5.3.2 Check that the outer casing of the equipment is complete and undamaged.

No tests with PAT or PAC instruments are required on double insulated equipment.

NB Items of Class O equipment may sometimes be found. These have a metal outer case, a 2-core mains lead, and do not carry the double insulation symbol. This equipment is of foreign manufacture and is not acceptable for use in the UK.

Class O equipment must never be passed as safe for use by any Authorised Tester.


  1. Portable electrical equipment is any equipment which connects to single-phase electrical mains supplies by a flexible cable and a 13 Amp plug, or which plugs into an adaptor supplied from a 13 Amp plug.
    NB - Extension leads and adaptors are included, and must be inspected and tested.

  2. Frequency of inspection and test will vary with equipment and use (see notes on 'Not to be used after' system).

  3. Equipment with a mains lead more than 3 metres long eg some overhead projectors, may fail the Earth Bond Test on PAT tester because of the resistance of the mains lead. In these cases only, a reading of 0.3 ohms or less will satisfy safety requirements.

  4. If all inspections and tests are satisfactory, fix an initialled and dated 'Not to be used after' label to the mains lead near the plug.

  5. If any inspection or test is not satisfactory, or you are doubtful of the results:take the equipment out of use immediately;

    label the equipment to show the reason for failure.

    inform your supervisor that the equipment is in need of repair, or more specialist inspection, before it can be put back into use.

  6. Equipment with plug-in, removable, mains leads
    This equipment should be inspected and tested according to this Code of Practice, with the mains lead in use at the time of test. If tests are satisfactory, attach a 'Not to be used after' label to the mains lead, and a second 'Not to be used after' label in a conspicuous position on the equipment. This ensures that if labelled equipment is used with a labelled mains lead, it is known that both have been tested. Seeing the label on the equipment will also draw attention to the existence of a removable mains lead.


These labels are to be used for all PAT testing and inspection work.

The White labels are for use on equipment where period between tests is two years.

The Yellow labels are for use on equipment where period between tests is one year or less.

Designation of test period

Two year period between tests - will include equipment which is rarely moved or unplugged from the supply and where the environment and use are not likely to cause any deterioration in electrical safety.

One year, or shorter, period between tests
- will include the majority of equipment which is unplugged and moved around very regularly, and any equipment which is used in a hostile environment eg exposed to moisture, heat, vibration, physical damage, etc.

This category will include all portable power tools, which should be inspected at no more than six monthly intervals or even more often if used in hostile conditions.

The label should be attached as a "flag" with the centre of the label wrapped round the mains cable of the equipment about three inches from the mains plug, and the two sides of the label stuck together to show Poly logo and title on one side and "Not to be used after" on the other.

The label can be written on with spirit-based permanent markers.

"Not to used after" should show "Month" and "Year"

"Tester" - initials of authorised tester

"Date" - date of test

Health & Safety Office