Installation resistance testing

[Simon Hall]

Hi everyone was wondering if any one could help me out I've just done a board change and went to do an installation resistance test on the whole board it failed L-N so I found the fault on down stairs lights so took that out and did it again L-N >299 N-E starts at 172 then reaches 247 & E-L starts at 157 gets to 225 yet when I do each circuit separate all the readings reach >299 surly the whole board should be the same. Thanks Simon

 

[Geordie Spark]

An INSTALLATION Resistance test ... are you sure???

 

[telectrix]

when you IR the whole board, you are getting a reading of all the circuits in parallel. therefore, you would expect the reading to be lower than the individual circuits. think of resistors in parallel.

 

[Marvo]

Firstly it will save you a lot of headaches if you IR test before you change the CU and quote accordingly for remedial work along with the CU change.

Secondly you're worrying about IR test results that are more than a hundred times better than required by the regs.
Finally the insulation resistances of each individual circuit will always be better than the global reading because the individual circuits are effectively in parallel.

 

[MDJ]

I am totally astonished to be honest, absolutely astonished?

 

[Marvo]

I am totally astonished to be honest, absolutely astonished?

If you're equally astonished at 2 circuits that are in parallel (A1 & A2) then your overall astonishment (At) could be defined as At = A/n where n is the number of circuits you were astonished at so At would equal A/2 in this case.

 

[Silly Sausage]

Simon, have a read of this...

 

[MDJ]

Simon, have a read of this...

Hey Archy, I liked your cow avatar, where is it? if you don't want it I may take it :lol:

 

[Silly Sausage]

Hey Archy, I liked your cow avatar, where is it? if you don't want it I may take it :lol:

Your wish is my command, She returns!

She's just been down the milking parlour.

 

[MDJ]

Best avatar I have seen for a long time fella, seriously love it lol

 

[Marvo]

She looks particularly fetching with that doily on her head. Where did you happen across her or was it just a random pic?

 

[Geordie Spark]

If you're equally astonished at 2 circuits that are in parallel (A1 & A2) then your overall astonishment (At) could be defined as At = A/n where n is the number of circuits you were astonished at so At would equal A/2 in this case.

Aye, ok clivvor shyte ...... haven't you got a spear to sharpen & a grass skirt to iron somewhere??

 

[MDJ]

Aye, ok clivvor shyte ...... haven't you got a spear to sharpen & a grass skirt to iron somewhere??

You have been watching ZULU haven't you fella? LOL

 

[Geordie Spark]

Your wish is my command, She returns!

She's just been down the milking parlour.

Is that Your Lass?

 

[Geordie Spark]

You have been watching ZULU haven't you fella? LOL

Several times .. it's hardly ever off the telly