Portable Appliance Tests Method / Procedures
All testing is carried out to the proposed guide lines HSE / IEE PM 32
Each appliance will be given a unique identification number, then:
In practice approximately 90% of all equipment defects are found during a preliminary visual inspection.
(1) The exterior of the equipment will be inspected for:
• Signs of overheating.
• Physical damage
• Signs of ingress of liquid or foreign materials
Particular attention will be paid to possible physical damage at accessible mains components such as switches, fuses and appliance couplers.
(2) All mains and power cords, including interconnecting cords, will be checked for physical damage. All flexible cords showing any sign of damage will be replaced.
(3) Where re-
• Terminations and cord grips will be checked for tightness
• Conductors will be checked for damage or loose strands
• Terminations will be checked for correct polarity
(4) Operator accessible fuses on the outside of the equipment will be checked for correct type and rating. If the equipment manufacturer has specified a particular rating for the plug fuse, this will also be checked. If the manufacturer has not specified a fuse rating for the plug the preferred fuse size will be determined and the correct size fitted and checks that properly manufactured cartridge fuses to British Standards are used
(5) Plugs with non insulated live and neutral pins will be replaced with British Standards approved insulated ones
If the manufacturer has not specified a fuse rating for the plug the recommended fuse size ratings are:
Luminaries 1 amp
Up to 700 watt 3 amp
IT Equipment/ Power Tools 5 amp
Above 700 watt 13 amp
CLASSES OF EQUIPMENT CONSTRUCTION
The equipment to be tested will normally be constructed in one or two basic classes; designated Class 1, 2. Constructional methods are summarized below with full details being found in BS2754.
Class 1: This equipment will provide the user with two levels of protection. The innermost level is the functional or basic insulation covering live internal parts. The second level of protection is provided by a conductive case which is earthed. This latter level of protection implies that Class 1 equipment could be a high hazard potential since it relies on the integrity of and electrical connection (the protective conductor or earth).
Class 2: This equipment also provides the user with two levels of protection with both levels being provided by insulation. Such equipment is generally described as “double insulated” and should carry the symbol shown below. The first protective barrier is the functional or basic insulation while the outer protective layer is known as the supplementary insulation which may comprise either of an insulating internal lining to a conductive case or in the majority of instances, form the case itself.
ORDER OF TESTS
(a) Perform the detailed visual inspection on unit to be tested
(b) Correct all faults and replace any damaged components (these may typically include plugs, sockets, cords, fuse holder, voltage selectors, switches etc.)
FIRST ELECTRICAL TEST
The first electrical tests will verify the integrity of the protective conductor (the earth) and every part of the conductive case which is designed to be earthed. This is a British Standards Type Approval test. (All IT and electronic equipment should be tested at 100mA this is a safe testing voltage – testing at higher values could degrade the electronics). The guide lines are: 1.5 times the design current of the unit under test but need not be greater than 25Amps. The resistance should not exceed 0.1 Ohm, but does not include supply cord / test cord
Standards Resistance between earth pin on plug to earthed metal parts less supply cord
BS 3456 Household Appliances (0.1 + R) Ohm
BS 4533 Luminaries 0.5 Ohm including supply cord
BS 2769 Handheld motor operated tools (0.1 + R) Ohm
BS 415 Electronic and related apparatus (0.5 + R) Ohm
BSEN 60950 IT equipment (0.1 + R) Ohm
SECOND ELECTRICAL TEST
The second electrical test performed is the insulation resistance test. For this test, the PAT testers join together live and neutral and apply a 500v DC voltage between these circuit conductors and earth. Such a test is a requirement of BS2754 “Construction of electrical equipment for protection against electrical shock”. This is a British Standards Type Approval test.
Class 2 equipment: -
INSULATION RESISTANCE TESTS
Standard Resistance between live parts and the body (Class 1) M/ohms Resistance between live parts and the body (Class 2) M/ohm
BS3456 Household Appliances 2 7
BS4533 Luminaries 2 4
BS2769 Handheld 2 7
BS415 Electronic and related 2 4
BSEN 60950 2 2
INSULATION RESISTANCE TESTS for High Loaded Heating Elements
Insulation to be tested Minimum insulated resistance Heating and Cooking
Up to 3 kW M/Ohm Over 3.1 kW M/Ohm
Between live parts and earthed accessible metal on class 1 1 3
Rated input in kW
Between live parts and metal parts on the body of class 2 3 3
THIRD ELECTRICAL TEST
A load test is not required by the Standards Authority bit is included to protect the test person from the hazards produced by a very low impedance being present between LIVE and NEUTRAL during the following ‘operation test’ requiring the tester to determine if it is safe to continue testing if a potentially high current is detected.
FOURTH ELECTRICAL TEST
EARTH LEAKAGE CURRENT MEASUREMENT
A final test will measure the total leakage current from LIVE and/or NEUTRAL to earth under operating conditions. The test is particularly relevant on electronic equipment where ‘flash’ testing has not been used. Although not a direct substitute for a flash test, the earth leakage test will provide evidence of possible deterioration of certain components under test and may indicate that the method of connection of the equipment to the supply is inappropriate.
Earth Leakage Limits
BS3456 Household BS4533 Luminaries BS7269 Handheld Tools BSEN60905 IT Equipment BS4343 Connected to Industrial Socket Connected to domestic plug and socket
Class 1 Not Hand held mA mA mA mA mA
Class 1 hand held 0.75 1.0 0.75 0.75
Stationary Class 1 0.75 or 0.75/ kW 3.5
Class 2 0.25 0.5 0.25 0.25
Extension leads should be treated as an appliance and tested in a similar fashion to removable mains IEC leads. They will be given a unique serial number then the following tests are conducted:
1. Visual inspection
2. Resistance of the earth conductor
3. Insulation resistance testing
4. Continuity of each conductor
5. Polarity of phase, neutral and earth connections
As the length of the extension cable will have an effect on the earth resistance, it is recommended that the following limits are observed
1.00mm sq 10 metres
1.25mm sq 12 metres
1.50mm sq 15 metres
2.50mm sq 25 metres
These limits cannot be exceeded unless protected by a 30mA – R.C.D to BS 7071
“Piggy Backing” of extension leads is not generally allowed unless additional earth bonding is carried out 2 and 3 way adapters are not allowed unless fused
1. To make a new log of all Portable Appliances.
2. Identify all equipment with its own unique number. This should be extended to continue and incorporate sequence numbers already in place. Also a passed tag with clearly visible retest date for all safe appliances
3. Record the test results of all Portable Appliances
4. Items that are found to be faulty, outside the normal scope of testing, will have a “DO NOT USE” label. This failed equipment will be brought to your attention to enable you to make the appropriate decision, we always attempt to leave all equipment operational.
5. Individual fail reports are produced
6. Ensure that the retests are carried out at the required frequency
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