Inspection and Testing of Electrical Equipment

The preliminary inspection procedure is to first determine whether the equipment can be disconnected from the supply and disconnect if permission is received. If permission is not received to disconnect the supply no tests should be completed. It should be recorded that the equipment has not been inspected or tested and noted accordingly.

Preliminary or Visual Inspection

This test involves an in-depth check of the visual integrity of the plug, fuse, cable and case of the equipment under test. The electrical supply is required to be off for a complete visual inspection to take place.

The inspection will include the following: –

• the plug top is examined to ensure it is in physically good condition, is free from cracks or damage, any signs of overheating and that the pins are insulated. The top is removed to establish the outer sheath of the flexible cable is securely gripped by the cable clamp, to check conductor lengths and the terminals sufficiently tightened and is correctly wired.
• the fuse is examined to ensure it is of the correct rating for the type of appliance, it is manufactured to BS1362 and have an ASTA symbol displayed.
• the flexible cable is inspected for any signs of deterioration ensuring its length is suitable and safe for the equipment and the way it is used; it is in good condition and free from splits, fraying or damage.
• the appliance is inspected for any signs of deterioration or damage which might allow contact with live conductors. The casing or cabinet is inspected to ensure it is free from damage and/or cracks, that it switches on and off properly and is in good working order and operates safely.
• Assessment of whether the equipment is suitable for the environment.

Any minor faults that are identified during the visual inspection, for example: damaged plugs, incorrectly rated fuses and loose connections will be rectified prior to the testing procedure.

In addition to the preliminary inspection some or all of the following tests are completed which are subject to the Class of the appliance.

• earth continuity test
• insulation resistance test
• protective conductor current
• touch current test
• substitute/alternative leakage test
• functional operation

Earth Continuity Testing

This test can only be applied to Class I equipment or lead cord sets. This test ensures that an earth connection is made between the exposed metalwork of the appliance and the earth pin of the plug top. Earth continuity tests made on computer equipment are “soft tests” of 100mA and no functional test is carried out on the personal computer central processing unit.

Insulation Resistance Testing

This test is performed between live conductors, i.e. phase and neutral, connected together and the body of the appliance. A test voltage of 500V dc is applied and the Insulation Resistance determined to ensure adequate protection is in place between the conductors. Sometimes when a test is completed at 500V dc, the voltage being used can trigger a false reading or the surge protection circuit. In this instance an alternative insulation test of 250V dc will be used as this will not trigger the surge protection within the appliance.

Earth Leakage or Protective Conductor Testing

An Earth Leakage or Protective Conductor test is an alternative or complementary test to the insulation test and is carried out on Class I appliances. The test is completed to measure the amount of current leakage and is measured from the internal live parts to Earth. The test will establish the level of this leakage and if this level is low enough to cause no harm to the user of the appliance. No insulation is perfect and there is always an amount of leakage even if this is nominal.

It can be used as an alternative to the insulation resistance test when the insulation test can’t be performed. When carrying out this test and using rotating machinery such as drills and grinding machines, always secure the appliance so that when the power is applied the appliance will not cause injury, once the equipment has been switched on and operating for a short period of time, the measurement is made and recorded.

Polarity Check

A polarity check is performed to make sure the live and neutral conductors are not crossed. This can only be done if access can be gained to both sides of a power cord.

Multi-way Adaptors and Extension Leads

Sufficient socket outlets should be provided so that multi-way adaptors and extension leads are not necessary. Inspection of the installation should decide what is reasonable in terms of safety and a report made to the duty holder if excessive numbers are being used. They should not be connected in series i.e. daisy chained.

Residual Current Device, Adaptors and Extension Leads

Residual Current Device or RCD adaptors and RCD extension leads are used to provide protection for persons using portable appliances particularly equipment outdoors. RCD Adaptors continuously monitors the power supply to an electrical appliance and cuts off the power within 40 milliseconds if an earth current fault is detected. This is fast enough to prevent a fatal electrical shock. Electrical appliances can become dangerous if the wiring becomes loose, if they or their power cords become damaged or if they get wet.

Point to Point Testing of Fixed Equipment or Appliances

Point to Point testing of fixed equipment or appliances is more difficult to inspect and test because of the nature of their attachment to the building fabric and their connection to the fixed wiring of an installation, usually via an isolator or fused connection unit (FCU). This doesn’t mean that only visual inspections are required for these types of equipment, they should still receive a full combined inspection and test at relevant intervals. These intervals or frequency of inspections and test should be determined by a risk assessment.

Fixed equipment testing can be undertaken during the Electrical Inspection Condition report. (formerly known as a Periodic Inspection report) of the fixed installation where the frequencies of any inspection and testing are like those for the fixed installation. Additional formal inspections may be required for equipment that could be subjected to higher use or have a greater potential for being damaged, e.g. hand dryers, fixed hairdryers etc.

Testing fixed equipment or appliances must be carried out by a competent person, in accordance with the specific tests for the Class of equipment. The person carrying out the inspection and testing: –

• must be competent to carry out safe isolation procedures
• must be competent to carry out this more complex arrangement of work
• must ensure safe systems of work are observed always
• must ensure all inspections and tests, are relevant to the class of equipment

Fixed appliances which have been designed to be secured in a specific location may require the isolation of the supply which must be agreed by the duty holder at the time of inspection. This testing will be subjected to the relevant Safe Isolation procedures however any limitations, which may have been imposed during the inspection and testing of the appliance, will be noted i.e. unable to isolate supply due to operational requirements.

Marking and Recording Results

Every appliance on passing the required standard to indicate that it is in a safe condition will have an appliance label attached to a suitable part of the equipment stating unique number, date of test and testing company details.

A record generated within an inventory/testing report stating:

1. Unique number (as noted on appliance label)
2. Appliance description
3. Date of test
4. Test engineer
5. Test results
6. Testing appliance, serial number and calibration date
7. Any relevant comments

Documentation

Upon completion of the testing electronic copies of the test reports shall be generated and forwarded to the duty holder who is responsible for the ongoing maintenance of the appliances. These reports will detail the appliances, their location at the time of testing, the results and any repairs completed. They are called the PAT testing Certificate Report. 

Appliances that FAIL the testing procedure will be listed separately and highlighted with any course of action required. In addition to the report, a certificate shall be provided for display on the premises to advise that all electrical appliances have been tested for electrical safety.

Failed Items

Those appliances found to be damaged or faulty and FAILING the inspection will be removed from service and marked with a FAILED label stating that the appliance is not to be used. The owner at the position of the failed item will be informed immediately and at the end of the day, the duty holder or responsible person will be advised of all failures, the reason for failure. The course of action will be decided by the responsible person or duty holder. At any point if the appliance can be repaired DRA PAT Testing will do so to reduce downtime.

Microwave Ovens

Microwave ovens provide a convenient and safe way of cooking food in the workplace; however, faults can occur and unless periodically tested they may become a health and safety hazard without you being aware.  Additional Requirements for Microwave Ovens are covered by the BS EN 60335-2-25 Safety Standard. DRA PAT Testing will perform additional tests to ensure the appliance under test is working optimally.

Microwave Power

This involves heating a known volume of water for a known period and calculating the power generated by the oven as a function of the period and difference in temperature generated in the water.

Microwave Leakage

Lack of cleanliness and poor maintenance of the door seals can lead to leakage levels that exceed the recommended limit. Testing of the unit involves measurement of the radiation levels around the oven using microwave detection instrument to ensure compliance with the 5mW/cm2 limit.

Door Interlock

The safety interlock switches and the door seals are inspected for any signs of damage to ensure that they function correctly and safety.