Insulation Resistance Test Standard For Cable

The insulation resistance test is the second test required by the electrical safety testing standards.

Insulation resistance test standard for cable.

Minimum acceptable insulation resistance for 600 v cable from 100 to 1000 feet. If during periodical testing insulation resistance of cable is found between 5 and 1 mω km at buried temperature the subject cable should be programmed for replacement. The insulation resistance test consists in measuring the insulation resistance of a. Principle of insulation testing and influencing factors insulation resistance measurement is based on ohm s law.

Developed early in the 20th century the insulation resistance ir test is the oldest and most widely used test for assessing the quality of insulation. Also acceptable values of insulation resistance depend upon the equipment you re testing. Insulation resistance decreases in temperature or moisture. Insulation resistance testing is a non destructive test procedure.

The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and. After dc overpotential test is completed the insulation resistance test is done again to assure that the cable has not been damaged by the hi pot. Cables for rated voltages of 1 kv um 1 2 kv and 3 kv um 3 6 kv reference number. Insulation resistance testing purpose.

Insulation resistance test data may be used to establish a trending pattern. The megger insulation tester is a small portable instrument that gives you a direct reading of insulation resistance in ohms or megohms. Test results are dependent on the temperature of the insulating material and the humidity of the surrounding environment at the time of the test. Power cables with extruded insulation and their accessories for rated voltages from 1 kv um 1 2 kv up to 30 kv um 36 kv part 1.

For cables rated 600 v the minimum acceptable insulation resistance values for cable lengths from 100 to 1000 feet would be as shown in the following table from ieee 525. It is commonly used in the industry for acceptance testing prior to energizing the cable and for maintenance testing programs. With a little record keeping and common sense however you can get a good picture of the insulation condition from values that are only relative. Regular testing of the insulation on an installation or machine is therefore a useful way of monitoring this type of deterioration so you can act before total failure occurs.

Deviations from the baseline information permit evaluation of the insulation. Table 100 22 minimum radii for power cable. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv.