Metrel Insulation Resistace

[DuaneMHunt1976]

Ive got a Mi3100 EasiPlus i think its called.


When doing Insulation Resistance test, i get figures all about the place 104MOhms then 102MOhms, not changed any thing..

On Testing it, closed i get 504M Ohms and it changes every time i do it, open i get 0 Ohms.
Im not used to this, every one ive used at college had =>199M Ohms or =>499M Ohms

tho i know that 2M Ohms is enough, still feel strange about all these random numbers
(might try and see if i can pick lotto balls with it tho)

Any one else use Metrel for Insulation Resistance testing

 

[Leesparkykent]

Have you tried new leads or having it calibrated?

 

[DuaneMHunt1976]

Have you tried new leads or having it calibrated?

Its Due Calibration next month but i need it done sooner..
Ive asked the company that dose the Calibration if they could do it sooner and is this normal..

Ill try other leads, i got one lead that goes off in to L,N,PE and another that is one big Prob and another one,
Ill try in the morning the other leads..

 

[davesparks]

Assumjng you are getting to linking the test leads together then you have got serious problems if it gives 0ohms when open and 504 M when closed!
If you have any reason to doubt the accuracy or reliability of the test instrument then stop using it to carry out testing straight away and check it out.

 

[DuaneMHunt1976]

Guessing coming from Electronics OPEN means Open Circuit in Logic the Gate is Open 0
and Closed meansing 1

never get a chances to use my boolean algebra, was very good at it in College
To the point that i had a Tutor claiming he got a Digital Circuit down to 2 logic gates for a die
pointed out he couldnt as i only got it down to 3, but as there is 4 in a pack might as well use them all.

 

[HappyHippyDad]

I've got one of those Duane. Every month (well almost every month!) I test it on my cal check to make sure it is within limits. Perhaps you could purchase one. At least with the calcheck you have a fixed resistance to check rather than a possibly varying one which you are basing your concerns on.
The MI3100 goes up to 1000Mohms so its just got a bit more of a range than your college ones.

 

[DuaneMHunt1976]

i do remember doing IR on the same circuit and i got 1000M, and i maked 1G on the paper work.. some thing must be off.. ill have a look it in the morning. but thanks.. may come back to you now and then about this

 

[stevethesparks]

Have you made a mistake with your explanation of closed and open testing, I'm hoping so?
If so and not faulty -
You need to check it against a stable reference as said by hhd.
Also, you may get varying results by small increments due to capacitive reactance in the cable.
If each successive reading increases, this is a good thing (although your description says the opposite). The Metrel will only test for a set time, if you used another instrument i.e. Fluke 1507, this can measure continuously and would demonstrate this one possible theory.
If your instrument proves to be ok and each successive reading decreases, you may need to look further into this.

 

[davesparks]

Have you made a mistake with your explanation of closed and open testing, I'm hoping so?
If so and not faulty -
You need to check it against a stable reference as said by hhd.
Also, you may get varying results by small increments due to capacitive reactance in the cable.
If each successive reading increases, this is a good thing (although your description says the opposite). The Metrel will only test for a set time, if you used another instrument i.e. Fluke 1507, this can measure continuously and would demonstrate this one possible theory.
If your instrument proves to be ok and each successive reading decreases, you may need to look further into this.

I was taught that if an IR test does not hit fsd immediately then the test should be applied for 1 minute before the reading is taken

 

[a-z electrics]

I have one of these testers. No probs usually with IR tests but it does play up on continuity when batteries are half depleted, usually when nulling the leads and sometimes gives open circuit when leads are connected. Takes several goes to get it correct and then seems ok but no problem when batteries recharged but it is a nuisance. I have a simple cal check box and the checks readings are consistent though.

 

[Darkwood]

Reinforcing the last post, if batteries are low you can ignore the readings you get, they will be all over the shop. I have a metrel and it always does this eventually if I ignore the Battery low symbol.

 

[Rob Smith 643]

How/where do you store your mft when not in use, particularly on site? If you leave it on a damp floor, say in a new build, you may find that when used it gives unreliable/inconsistent readings until it 'warms up'. Perhaps...