Testing IEC Leads and Mains Extensions

Most modern PAT testers have a handy IEC lead test facility. All one has to do during PAT Testing is to plug in both ends of the lead and test Earth Continuity, Insulation Resistance and Polarity. The Polarity test just checks that the lead is wired correctly. This can only be done if one has access to both sides of a power cord.

On other PAT testers there is a facility for a 2-stage test of power leads. The first stage is a test of Earth Continuity and Insulation Resistance by plugging both ends of the lead into the PAT tester. The second stage is a check of the polarity by plugging the power lead into the mains and the other end to the tester. Couple of lights on the PAT Tester show whether the polarity of the power lead is correct or wrong.

PAT Testers that do not have this facility can use a power lead tester that is available as an accessory. This is used in a 2-stage test.

Stage 1: The lead is plugged into the PAT Tester and the lead tester. The test lead is clipped onto a post provided on the IEC lead tester and the Earth Continuity and Insulation Resistance test is carried out.

Stage 2: The power lead is now plugged into a mains socket and also into the IEC lead tester. The two lights on the tester show whether the polarity of the IEC cable is correct or faulty.

When PAT testing long IEC leads one needs to remember to adjust the pass limits as outlined in the IEE Code of Practice.

PAT Testing Mains extension leads

If a PAT Tester has an IEC lead test facility, then this can be easily adapted to test mains extension leads as well. All one needs is a short IEC lead to connect the socket of the mains lead back into the PAT tester as shown. A similar method can also be used if the PAT Tester has a 2-stage IEC lead test.

PAT Testers that do not have an IEC lead test facility at all can use the IEC lead tester. This is used in a 2-stage test as outlined below.

Stage 1: The mains lead is plugged into the PAT Tester and the short IEC lead is plugged into the mains lead and the IEC lead tester. The test lead is clipped onto a post provided on the IEC lead tester and the Earth Continuity and Insulation Resistance test is carried out.

Stage 2: The mains extension lead is now plugged into a mains socket. The short IEC lead is plugged into the mains also into the IEC lead tester as shown. The two lights on the tester show whether the polarity of the mains extension is correct or faulty.

When PAT testing mains leads, please note the following:

• Depending on the length of the extension lead, adjust the Earth Continuity pass limit when carrying out the PAT testing.

• When PAT testing a multi-way mains extension, it is important to check every outlet for good Earth Continuity. If any one socket should fail then the whole extension lead must be failed and discarded.

• During PAT testing if the Insulation Resistance test is carried out at 500V, then one will get a fail if the extension lead has surge protection. In this case use a 250V test if one is available on the tester. If this is not available then make a suitable note in the test record and pass the appliance. Some testers such as the BattPAT from First Stop Safety do not have this problem as the Insulation Resistance test is always done at a voltage of 350V.

• It is important to un-reel any coiled extension leads to inspect for any damage to the cable prior to any PAT testing.

• Long extension leads have a higher power rating when un-coiled compared to when they are coiled. During PAT testing, when carrying out the Earth Continuity test at a current of 25A, care needs to be taken not to do this over a long period as this might lead to over-heating. Normally PAT testers limit this to 5 seconds which should not present a problem.

• Some extension leads may have an RCD built in. If this is the case, please refer to Test Examples 8 when carrying out the PAT testing

Users of extension leads must be made aware of the following:

• Long extension leads have a higher power rating when un-coiled compared to when they are coiled. If the user intends to use the extension lead to power say a 2kW heater, then it is very important that it is fully uncoiled. If it is not coiled, then there is a risk of a fire breaking out.

• An extension lead wired with normal 13A cable should not be longer than 12 meters.

• An extension lead must not be plugged into another extension lead such that their total length exceeds 12 meters.

• If the extension lead is longer than 12m, then it must be fitted with a Residual Current Device (RCD) with a rated operating current not exceeding 30mA.

• Care should be taken to route the extension lead away from work areas and not across paths where they might get caught and pulled, or run over and damaged.