The ‘earth fault loop’ refers to the overall fault path for electrical current to flow in the event of an electrical fault. In general terms, the lower the fault loop impedance, the greater the amount of current will flow in the event of an electrical fault. This may sound horrific; however, the large amount of fault current will enable a protective device to operate quickly to isolate the fault and stop the flow of current.
Measuring the earth loop impedance of an installation is important for maintaining both the efficiency of an electrical installation under prospective fault conditions, but also for reducing the risk of electrical shocks and fires taking place due to a defective means of earth. The majority of loop testers will also display a Prospective Fault Current (PFC) or Prospective Short Circuit Current (PSCC) value based upon the loop test impedance result.
It is important for a contractor to have the correct test equipment to carry out a loop impedance test to certify that an electrical installation is safe for use and not a potentially life-threatening installation.
In very simple terms, a loop tester operates on the principle of Ohm’s law. By varying the amount of resistance placed across the line and CPC conductor within an electrical installation, a fault current will naturally circulate within the loop. The instrument will then calculate an impedance value by dividing the fault current by the supply voltage.
Test-meter.co.uk offer a variety of loop testers in stock. From standard loop testers, to models that offer a low current anti-trip test, you can be sure that we can cater for your loop testing application.