Basic Testing Procedures
General:
All items will be tested in isolation. That is: Any equipment interconnected by means of mains or data cables will first have these interconnections removed (this includes the disconnection of "networked" equipment from the network cabling system). If necessary, operations must be requested to "shutdown" systems prior to testing.
The portable appliance tester must be plugged into a 13A socket outlet and the correct date set by following the prompts on the display panel and using the appropriate keys.
The appliance and site codes will be entered for each test.
The test code facility will only be used to alter the test parameters where necessary.
NOTE: Hard wired equipment will be disconnected from the associated outlet, having first isolated the mains supply at a suitable point. Testing will take place via the "SAFE BLOC" wire to plug top adapter.
1) EARTH BOND IMPEDANCE TEST - For CLASS 1 appliances the 8 Amp earth bond terminal on the tester will be utilized for appliances fused up to 3 Amps and the 25 Amp terminal for appliances fused between 5 and 13 Amps.
The earth impedance limit will be set according to the size and length of the connecting flexible cord. Typical nominal resistance's values are given in Appendix 3.
NOTE: The British Standards for most IT. Equipment specify an earth bond impedance of 0.1 Ohms. This figure does NOT include the additional impedance/resistance of a flexible cord and plug top. Generally speaking a reading of 0.25 Ohms or less can be considered within acceptable limits for equipment using a 2 metre length cord with 0.5 square millimetres or greater conductors.
The tests engineer will take sufficient care when connecting the earth clip to CLASS 1 appliances to ensure that proper contact is made and thereby reduce the possibility of incorrectly failing an appliance (earth connections can be looked for with a simple Ohm Meter prior to testing with a PAT). Prior to failing any items as a result of an abnormally high earth impedance, the test engineer shall first check that all associated equipment has been disconnected (thus removing potential parallel earth paths) and that the Test clip is securely attached to the item in question. It is recommended that this test be repeated at least three times to eliminate such problems.
2) INSULATION RESISTANCE TEST - Unless the equipment manufacturer/supplier specifies otherwise, insulation resistance testing (at 500V dc) will take place with the appliance mains switch in the "OFF" position. This is due to the fact that the majority of IT. Equipment power supplies utilize filters and protective devices. These are generally rated at 240 Volts, or just above, and tend to be connected across Live and Neutral and earth. Thus a standard PAT insulation test would greatly over stress these components and would in fact reduce the longevity and safety of the appliance. It may, in some cases, be possible to remove these "sensitive" components prior to testing, but generally speaking this is considered impracticable.
3) LOAD TEST - A load test will be carried out to protect the test engineer from possible hazards produced by a very low impedance being present between Live and Neutral during the OPERATION TEST. The test will be performed with the equipment turned "ON", and failure will halt further testing.
4) OPERATION TEST - An operation test will be performed to ensure that the equipment under test does NOT draw excessive current (the results obtained will not differ significantly from the manufacturer specification). Abnormally low currents will indicate open circuits or ruptured fuses which will be reported/repaired.
5) EARTH LEAKAGE TEST - This test will take place to measure the total current from Live and/or Neutral to earth under operating conditions. A result of not greater than 3.5 mA will be recorded.
NB: Certain noise suppression components may give rise to a failure result. The equipment manufacturer/supplier will be consulted where there is any doubt
Failures:
For any equipment failing Electrical Safety tests, a procedure will have be previously discussed with the customer, as to the action required of making safe any equipment. Should it be decided to remove any equipment from service, the flexible cord will be turned around the plug and secured with a nylon cable tie in such a manner so that the plug top cannot be inserted into a socket outlet. A "FAILED - DO NOT USE" label will be affixed in a prominent position on the equipment and the Premises Manager and Network Services Department notified immediately. A "FAIL" status will be entered against the item on the Equipment Register. A list of all FAILED items will be presented to the Premises Manager and Network Services Department or nominated contact at the end of each day.
On Site Repairs:
Where a plug tops, fuses or flexible cords are replaced/repaired, the appropriate entry will be made on the equipment register. The repairs will be carried out prior to electrical safety testing unless other irreparable defects are apparent which would cause the appliance to fail.
Downloading Results and Preparing Reports:
All information copied down on the paper equipment register will be entered onto the computer database version, prior to the down loaded of test results from the PAT tester(s).
Results will be down loaded following the set procedures and all entries will be checked for their integrity.
Current results will be checked against previous years results where applicable. Where significant deterioration is apparent the Premises Manager and Network Services Department will be informed, in writing, via the final report.
Upon completion of the testing phase, final printed versions of the equipment register and all test results and notes will be presented to the Premises Manager (in the form of a report) and will be kept on site, by him, for presentation to Local Authority Inspectors.