insulation test

[noel2507]

Hi just a quick question about insulation resistance test that is bugging me. Why when carrying out an insulation resistance test does the meter climb slowly sometimes and other time gives a result straight away. Also what is the minimum result you would expect from a brand new house? Added a loft light to a new build last week and the insulation resistance test for some of the circuits was really low. Thanks very much for your time with this.

 

[Andy™]

if there is some dampness, you may get a reading which slowly increases.

for a new install, IR should be max of meter

 

[Evans Electric]

As Andy says , dampness can do it, or you may be meggering a fluorescent fitting or a neon indicator, a faulty immersion heater, lighting trannys.

 

[m4tty]

Someone said a while ago on here that it's charging the circuit as your holding the test button down.

 

[sparkytim]

It will

Thats why it is good to "discharge" it by keeping the leads connected after you let go of the test button and watch the needle return to 0, as you can get a shock from the ends if YOU discharge it.