An important check which is often ignored by contractors when connecting new houses is the verification of polarity. While ESB Networks get this right 99% of the time, there is always the danger, particularly in rural areas that phase and neutral can be reversed.
Anybody who is familiar with the bundles type overhead conductors knows that the only difference between phase and neutral is a single raised ridge running along the length of the phase.
In wet or cold conditions it is sometimes hard to feel this ridge and even then mistakes can be made when making the final connections. It is vital that a contractor, before making connections, ensures that the incoming phase and neutral are at the correct terminals in the meter or isolator.
This can be quite easily done by checking for voltage between the incoming live and the customer’s main earth. The voltage should be equal to the voltage between the incoming phase and neutral. If there is a substantial difference between the phase/neutral voltage and the phase/earth voltage, no connection should be made and ESB should be contacted.
Quite apart from verifying polarity of the incoming supply, this test also verifies the efficiency of the customer’s main earth electrode. It takes less than a minute to carry out the test and doing so can prevent serious damage to the installation or injury to occupants to the premises.