This test is performed on all Courses I home appliances during PAT Testing. The purpose of the test is to check that there is an excellent connection between the Earth pin on the plug as well as the case of the home appliance A good link is specified as having a resistance of fewer than 0.1 ohms (or 100 milliohms).
The Earth Continuity test is sometimes referred to as the Earth Bond test or the Earth Resistance test. In effect, they all measure that there is an excellent link between the keys plug and also the Earth factor. The standard means to perform this test is to plug the appliance into a PAT Tester as well as clip the Test cause an appropriate earth factor.
When the test is done, if the resistance measured is less than 0.1 ohms, after that, there is an excellent earth link, as well as the device, is considered risk-free. When performing this test throughout Pat testing, there are a variety of practical points to be considered.
Planet point on the appliance
To execute this test, it is very important naturally to clip the test to bring about an appropriate earth factor. If this is not done, after that there is no return course for the existing during PAT testing. This will certainly lead to the device falling short of the test.
Discovering an appropriate planet point will feature experience. It is essential to get a great connection to the Planet point. Rusty steel or scaling on kettle components may prevent an excellent low resistance connection. If this holds after that turn the port as well as make use of the teeth of the crocodile clip to scratch away the corrosion or the scaling to get an excellent connection. It is likewise acceptable to clip onto a screwdriver and also use this to link to a Planet point.
The Principle is: When testing Planet Connection if you do get a fail initially, do not promptly fail the appliance. See to it you have an excellent connection and try PAT testing once again. If essential try various Earth factors as not all steel components might be linked to the planet.
PAT testing – Class I Plastic devices
In some classes, I devise it might not be possible to access an exterior earth point if the appliance is confined in plastic. As an example, there are lots of electrical fans being used which come under this classification. This provides us with trouble because if we can not link the test lead to an earth point, there is no circuit made, and also the Planet Connection test will certainly fall short.
On these appliances, it is essential to recognize that their construction makes them safer than standard Course I steel home appliances. In addition to having an Earth connection, they are enclosed in plastic giving them an added layer of security. The way to carry out PAT testing on these home appliances is to still carry out the Insulation Resistance Test. If this passes, then tape-record this hand down the Equipment Test Document and comment on the impact that the earth Connection test could not be carried out due to the plastic enclosure.
PAT Testing – Test Current
The person carrying out the testing can make use of one of both alternatives listed below.
Choice 1: Use a test current of 1.5 times the fuse suited the plug up to an optimum of 25A. For example, when testing a pot with a fuse of 13A, a test current of 25A ought to be utilized. When testing a light fitted with a fuse of 3A, a test current of around 4.5 A is made use of. The existing is usually obtained a period of between 5 and also 20 seconds. This test ought to NOT be made use of on IT or other devices where there are electronic elements in use. The big currents streaming in the earth conductor have been understood to cause rise voltages that have damaged digital elements.
Alternative 2: Make use of a test current of between 20 and 200 mA. Whilst this test is being accomplished the cable television should be flexed to bring out any kind of apparent mistakes. This is a secure test as well as can be utilized on ALL Course I home appliances including IT equipment.
PAT Testing – Test Limitations
As stated above, to pass this test, the Planet Connection resistance has to be less than 0.1 ohms when PAT testing is carried out. As this is from the pin on the plug to the Earth factor, an allowance can be created for the Keys lead that is made use of on the device. For example, a Class I lamp has a 5m keys lead (the present ability of 3A) connected to it. The total resistance of this lead is 0.195 ohms. This set would certainly include the 0.1 ohms for the appliance itself to give a restriction of 0.295 ohms. When testing this lamp for earth Continuity, if the resistance was say 0.22 ohms, after that one would pass the home appliance. State a PC has a 5m wire of existing capability 13A. The complete resistance of this is 0.078 ohms. The pass limitation for this PC would be 0.1 + 0.078 which is 0.178 ohms.
If the home appliance has a short mains lead, then this will certainly not contribute a whole lot to the earth resistance. For instance, a 1m cord for an electrical fire would have a resistance of only 0.015 ohms. When utilizing a PAT Tester with a display, the user will be able to work out whether the device passes or stops working whilst taking the length of the keys to introducing an account. On Pass/fail PAT Testers, there is an automatic allocation created for the mains lead. Generally, the limit is set to around 0.25 ohms to allow for up to 5m of mains cord. On some Pass/Fail PAT Testers, allowance can also be created longer cords, claim when testing 10m or 20m extension leads.
