Insulation resistance help

[Pauldicker]

I'm still a newbie but here goes.
as part of my Elecsa assessment I have changed the outlaws 1970's Fuse board to a new 17th edition cu.
the wiring is still original as well. Due to equipment that I cannot get to or remove I bridged the line to cpc and tested between that and neutral. On all the circuits results were between 230 to 1200 M ohms.
is this still a pass and what would be expected of 40yr old cable or am I doing something wrong.

 

[Plonker 3]

Is that 230 ohms or 230 M ohms for the lowest value?

 

[Pete999]

Why not link L and N and carry out an IR test @240v between LN to E.

 

[telectrix]

I'm still a newbie but here goes.
as part of my Elecsa assessment I have changed the outlaws 1970's Fuse board to a new 17th edition cu.
the wiring is still original as well. Due to equipment that I cannot get to or remove I bridged the line to cpc and tested between that and neutral. On all the circuits results were between 230 to 1200 M ohms.
is this still a pass and what would be expected of 40yr old cable or am I doing something wrong.

so you still managed to bang 500V d.c. across L and N.

 

[Pauldicker]

Why not link L and N and carry out an IR test @240v between LN to E.

Yes sorry typo, I bridged line and neutral and tested between line/neutral and cpc.

 

[Silly Sausage]

Yes sorry typo, I bridged line and neutral and tested between line/neutral and cpc.

I was hoping that was the case!

 

[telectrix]

i retract my post then.

 

[Pauldicker]

Sorry for the typo. I joined the line to neutral bar and tested between line/ neutral and cpc.

My kt65 measures I'm M ohms so 230 was in M ohms

 

[Sintra]

If the results are in M ohms then there's not an issue.

 

[Plonker 3]

You should buy, read and understand GN3 for guidance on what readings you should expect when testing.

 

[Pauldicker]

You should buy, read and understand GN3 for guidance on what readings you should expect when testing.

I do have GN3, however when I done my course everything was new and readings were always >2000 M ohms,

I'm just asking if these readings are about right for old wiring and when inspected by Elecsa will they allow the results.

 

[R G]

230M ohms is good for old wiring , but tell me what test equipment are you using to get 1200M ohms , i use Robin/fluke and I get max of 500M ohms only , over that is infinity ..

 

[Risteard]

Sorry for the typo. I joined the line to neutral bar and tested between line/ neutral and cpc.

My kt65 measures I'm M ohms so 230 was in M ohms

What does BS 7671:2008 (2013) or BS 7671:2008 (2015) say on the matter? That is your answer.

 

[Plonker 3]

I do have GN3, however when I done my course everything was new and readings were always >2000 M ohms,

I'm just asking if these readings are about right for old wiring and when inspected by Elecsa will they allow the results.

The answer you are looking for is contained within GN3

 

[Tug]

230M ohms is fine, nowt to worry about.

 

[Pete999]

The answer you are looking for is contained within GN3

To Pauldicker that's probably because the tester you were using had a max reading of>2000Mohms mine tester's max is >209Mohms

 

[Delboybully]

230M ohms is good for old wiring , but tell me what test equipment are you using to get 1200M ohms , i use Robin/fluke and I get max of 500M ohms only , over that is infinity ..

I have a kewtech KT64, Max IR is >1999 M

 

[trev]

I do have GN3, however when I done my course everything was new and readings were always >2000 M ohms

So with all due respect mate, didn't you think to read it?

 

[Plonker 3]

So with all due respect mate, didn't you think to read it?

Why waste time looking info up in a book when there are mugs on the internet falling over themselves to provide the correct answer for you.

 

[Pauldicker]

230M ohms is good for old wiring , but tell me what test equipment are you using to get 1200M ohms , i use Robin/fluke and I get max of 500M ohms only , over that is infinity ..

I am using a kewtech kt65dt 8in1 tester. I believe it goes to > 2000m ohms
thanks to those that have been helpful.
Gn3 does not tell you what to expect with older wiring. So some of the more derogatory comments are not helpful, as I said I'm still a newbie and I'm sure you were all at that stage once!

 

[Deleted member 9648]

I do have GN3, however when I done my course everything was new and readings were always >2000 M ohms,

I'm just asking if these readings are about right for old wiring and when inspected by Elecsa will they allow the results.

Thats gotta be one of the best answers I've ever seen on here....this forum is now officially of more use than a guidance note.

 

[Sintra]

I am using a kewtech kt65dt 8in1 tester. I believe it goes to > 2000m ohms

Mate regardless of what the meters maximum reading is its how you interpret the readings that count.

 

[Silly Sausage]

Thats gotta be one of the best answers I've ever seen on here....this forum is now officially of more use than an interactive guidance note.

:smilielol5:

 

[davesparks]

I am using a kewtech kt65dt 8in1 tester. I believe it goes to > 2000m ohms
thanks to those that have been helpful.
Gn3 does not tell you what to expect with older wiring. So some of the more derogatory comments are not helpful, as I said I'm still a newbie and I'm sure you were all at that stage once!

It does give you the minimum required values for circuits operating at various voltages t​hough.

 

[7029 dave]

I know the value of my old girl.

 

[Simonslimline]

What is the point in performing a test if you are not even sure what values are compliant!

It's all written in BS7671 or also GN3 in this case.

 

[SPARTYKUS]

The point being,

this is a forum of strangers! I might happen to be lying through my teeth!

Read the answers in the horses mouth.

 

[PEG]

Having read a few,similar threads,regarding interpreting results,it appears to me,that some uncertainty,is injected,by trainees/newbees concentrating on "the" results,their chosen test device,displays.
A lot of them stick like glue,to a device they trained with,or were shown how to test with,initially.

This reluctance to swap,change or try other types of test equipment,occasionally causes a lack of confidence when deciding how results stand.

For example,some lads feel,a device which reads to >1999,and can give a reading of,say,805 Meg,is a better machine than one which reads to >300, even though we all know the limits in GN3 are at the other end...

Sometimes my own IR tester gives varying results.....i think i'll oil the handle bearings....:icon12:

 

[trev]

Having read a few,similar threads,regarding interpreting results,it appears to me,that some uncertainty,is injected,by trainees/newbees concentrating on "the" results,their chosen test device,displays.
A lot of them stick like glue,to a device they trained with,or were shown how to test with,initially.

This reluctance to swap,change or try other types of test equipment,occasionally causes a lack of confidence when deciding how results stand.

For example,some lads feel,a device which reads to >1999,and can give a reading of,say,805 Meg,is a better machine than one which reads to >300, even though we all know the limits in GN3 are at the other end

CRIPES WHAT ARE YOU SAYING MAN! My old Metrel went to >1999 meg. My new Dilog only goes to >200 meg so the old one must be >1799 meg better!
Stands to reason innit?

 

[telectrix]

my analogue fault finding megger goes up to a fart and a whisker past 50Meg. i know the 50Meg is OK, but nowhere in GN3 can i find a fart or a whisker. this is why you have to interpret the readings.