Wire Cable Insulation Resistance Test Values

The results obtained from ir test are not intended to be useful in finding localized defects in the insulation as in a true hipot test but rather give information on the quality of the bulk material used as the insulation.

Wire cable insulation resistance test values.

Insulation resistance testing of low voltage cables in the field. Hands down without a doubt one of the most universally searched topics on ec m s website from a historical perspective is insulation resistance testing as a result some of our most popular evergreen articles like understanding insulation resistance testing continue to top the charts when it comes to most popular content. A rated line to line voltage for three phase ac machines line to ground voltage for single phase machines and rated direct voltage for dc machines or field windings. The international electrical testing association neta specification maintenance testing specifications for electrical power distribution equipment and.

You perform this insulation resistance test on the cable and record the data on a copy of the attached form. Also acceptable values of insulation resistance depend upon the equipment you re testing. If insulation resistance of the cable is found between 1000 and 100 kω km at buried temperature the subject cable should be replaced urgently within a year. You have a single conductor 500 kcmil 15kv cable.

Wire and cable manufacturers use the insulation resistance test to track their insulation manufacturing processes and. Even when not required by the end customer many wire and cable manufacturers use the insulation resistance test to track their insulation manufacturing processes and. The results obtained from ir test are not intended to be useful in finding localized defects in the insulation as in a true hipot test but rather give information on the quality of the bulk material used as the insulation. B kv is the rated machine terminal to terminal voltage.

Installation insulation resistance tests are only to be performed on new wire and cable. The resistance values will increase over time due to capacitive and insulation charging. For a good cable you will see results similar to those on the following page. Curve a shows test values as measured.

Figure 4 typical record of insulation resistance of a mill motor. 3 shows a typical scale which reads increasing resistance values from left up to infinity or a resistance too high to be measured. For cables rated 600 v the minimum acceptable insulation resistance values for cable lengths from 100 to 1000 feet would. Ansi neta mts 2015 table 100 11 insulation resistance test values rotating machinery for one minute at 40 c.

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. Values based on ieee std 43 2013. Historically many field electricians use the somewhat arbitrary standard of 1 megohm per kv.