Accessibility statement

Electrical safety

The following describes the Department of Biology's policy and procedures for in-service testing of electrical equipment (portable appliance testing (PAT)).

The departmental policy & procedures cover all appliances connected to the mains by BS1363 13A plugs or IEC 60309 industrial connectors, including 3-phase. This includes all portable, moveable, transportable, hand-held, stationary and fixed appliances.  3-phase equipment is only tested in house if the appliance is connected to the supply via a plug.  External contractors are contracted by the Department to test equipment connected to the mains via a fused spur or hard-wired into an isolator.

Please note that the electrical safety of equipment brought in for demonstration or on loan is the responsibility of the supplier

Scheduled Testing Frequency

Schedule Test intervals are in accordance with the Institute of Electrical Engineers Code of Practice (IEE CoP), taking into consideration past experience of operating a testing system together with information on faults found. The frequency of testing will be monitored and reviewed on a regular basis. Equipment will be tested before a scheduled test if a visual user inspection indicates a problem, or if the equipment is repaired or modified.

Laboratory Equipment:

•    laboratory equipment (broad term used to describe most non-office equipment) will be tested on a 2-year cycle
•    all Class 1 and Class 2 items will receive a combined formal inspection and test - there will be no intermediate formal visual inspection *
•    detachable mains leads will not be tested or recorded as a separate item

Office Equipment:

•    all office equipment will be tested on a 5-year cycle
•    all Class 1 and Class 2 items will receive a combined formal inspection and test*
•    there will be no intermediate formal visual inspection.
•    detachable mains leads will not be tested or recorded as a separate item

Equipment Stored / Not in Use

•    will not be tested at the time of scheduled routine inspection
•    a label will be affixed to the equipment stating that it must be safety tested before future use
•    this non-scheduled testing will be carried out by the Infrastructure Team

Hand-Held Tools:

•    Hand-tools (drills, angle grinders etc.), e.g. those used in the Mechanical Workshop, will be tested on a one-year cycle
* Only full tests are carried out as there is no meaningful advantage (in terms of the time a test takes) between a formal (i.e. recorded) visual examination and a full test.

Visual Inspection

Electrical appliances will be inspected for obvious damage or defects. Visual inspection of equipment will include checking:

  • for damage to the appliance which could affect the integrity of the insulation
  • for damage to the mains cable
  • that equipment has an appropriate mains fuse fitted in the plug
  • wiring on non-moulded plugs
  • for presence of adapted continental plugs:
    • Continental (Schuko) plugs on higher powered appliances, when used with UK adaptors, are undesirable; as a precautionary measure these will be replaced with UK 13A plugs when fitted to fridges, freezers and heated appliances.

Earth Bond Test

  • The earth bond Pass limit for a Class 1 test is 0.1ohm + R, where R is the resistance of the mains cable. The limit therefore depends upon the resistance of the protective conductor in the supply cord, which depends upon its length and cross-sectional area. The fixed limit will be of 0.1 for the appliance plus 0.1 for the cord giving a fixed limit of 0.2ohm. This corresponds with the fixed limit of the Seaward PrimeTest 100 and 250 PAT Testers
  • The pass limit for a detachable Class 1 (e.g. IEC type) cord set is also 0.2ohm
  • Test current will be either 1.5x the value of the fuse fitted in the plug, or between 20mA and 200mA

Insulation Resistance Test

Insulation Test Pass threshold is 1MΩ for Class 1 appliances, 2MΩ for Class 2 appliances.

Functional Tests

Functional tests will only be applied to equipment with an on / off light which may present a hazard if the light is not working e.g. laboratory hot-plate.

User checks

There is an expectation that all users of electrical equipment regularly check for damage/defects of equipment, leads and plugs.  All problems should be immediately identified to the Electronics Workshop.

Testing of new equipment arriving at Biology Stores

The ‘Provision and Use of Work Equipment Regulations’ states that new equipment should be visually inspected ‘after installation and before being put into service’ and ‘after assembly at a new site or location’. There are also legal duties on manufacturers and suppliers covering the initial integrity (safety) of new equipment which should ensure that new equipment intended for the UK market will arrive in a safe condition for immediate use.

All new equipment (and leads) arriving at ‘Goods-In’ (Biology Stores) will be visually inspected for any obvious damage or defects as part of the logging in process.  If an item gives any reason for concern, it should be referred to the Electronics Workshop.

Testing of equipment brought into the Department

Equipment brought into the Department by workers or the public can be potentially dangerous. Provided that the equipment is to remain in the Department, it is departmental policy that Electronics Workshop is informed of all such equipment and it is subject to electrical safety testing and visual inspection. 

If equipment, such as that provided for demonstration or evaluation purposes for a short period of time, is brought into the Department, the responsibility for testing lies with the supplier.


PAT labelling

  • A green Test Pass label will be affixed to all tested equipment.  This will indicate that the equipment has been tested satisfactorily i.e. has been passed as safe, and when the date of the next test is due
  • A strict test interval will be applied to hand-tools which are tested on a one-year cycle. These will be affixed with a red “do not use after __/__” label after testing, in addition to the standard green Test Pass label
  • Certain items regarded as ‘medium risk’, e.g. metal-bodied kettles, used in an office environment, will be tested every 2 years. These will be tested more frequently than other equipment in the same environment, and for that reason they will have a red “Do not use after __/__” label affixed after testing
  • Any item that fails a safety test will be clearly marked with a red Test Fail label, and will have the mains fuse or the plug removed
  • A label that reads ‘This equipment must be electrical safety tested before use’ will be placed on all stored equipment that is currently not in use.