IR Testing on domestic installations.

[electek]

Hi All ,
When testing insulation resistance on a domestic lighting circuit do you just join live/neutral and test down to earth otherwise if your testing live to neutral presumably you have to close all switches and remove all the lamps in the circuit.

Thanks Chris

 

[acat]

IR test is with all loads removed

Tests are line to neutral
line to cpc
neutral to cpc

If however you have anything in the circuit that you cannot remove ie neons then the test on that circuit would be line and neutral on one clip and earth on the other clip


Hope that helps


Chris

 

[electek]

Hi , thanks for the reply.

Yep , I understand about l-n , l-e, n-e tests which are obviously easy to carry out on a ring final circuit but in the specific case of a domestic lighting circuit , how exactly would you go about it ? Would you go round , turn on all switches remove all lamps or for the case of the lighting circuits would it be sufficient in the event of a part p assessment to just link live and neutral at the board and test down to earth ?

Any advice appreciated.

Thanks
Chris

 

[rodney12]

Joining L+N together would normally be ok for doing periodics but you mention Part P assessment.

If it's initial verification of a circuit you've installed for your assesment i would say that you would need to do all the tests. (to show the inspector you can do all the tests) as you would have had to have filled out an EIC anyway to show the inspector.

hope that makes sense

 

[davelerave]

Hi , thanks for the reply.

Yep , I understand about l-n , l-e, n-e tests which are obviously easy to carry out on a ring final circuit but in the specific case of a domestic lighting circuit , how exactly would you go about it ? Would you go round , turn on all switches remove all lamps or for the case of the lighting circuits would it be sufficient in the event of a part p assessment to just link live and neutral at the board and test down to earth ?

Any advice appreciated.

Thanks
Chris

a full test will be all switches on and all lamps removed .................. 2-ways have to be changed-over as well

 

[electek]

Is a part 'p' inspector likely to ask you to do IR Tests on a lighting circuit and hence remove all lamps e.t.c. or is he just gonna ask you to do it on a ring final circuit ?

Anyone any experience of this ?

Cheers
Chris.

 

[acat]

The one I had did


Chrix

 

[electek]

Acat , he asked you to do IR on the lighting ? what exactly did you do ?

Chris

 

[sythai]

and hence remove all lamps e.t.c

Hope he's got a while if this is the case on my assement, got at least 30 down lights plus other pendants etc !!

 

[electek]

Sythai , Thats what I was thinking !

Surely on an assessment the last circuit they would ask you to perform IR Tests on would be the lighting circuits ? Due to the fact its not really prectical.

I would have thought that if they were looking for IR tests they would be on Socket circuits or perhaps a shower circuit where you can simply remove the load and test live-neutral , live-earth and neutral to earth

Any comments most welcome

Regards

Chris

 

[sythai]

What date is your assesment booked for?

 

[nickblake]

I had one that did to ,ran round like a nutter taking all the bulbs out , i tested at 250 volts first just in case id missed one , i had blinkin 12 volt down lighter in the shower disconnected that when you have alot of12 volt down lighters in this situation its almost impractable to remove the transformers so the circuit was tested live to earth neutral to earth and omited the L to N

 

[electek]

Sythai , Not booked my assessment yet , about to start on the Consumer Unit change as my main job !

 

[electek]

Nickblake , Yep , so thats the same as joining live and neutral together and testing down to earth isn't it ?

 

[sythai]

It'll let you know what happens......... got mine on 17th June.

Cheers,

Sy

 

[electek]

Sythai , Yep , let me know mate - good luck hope all goes well

 

[nickblake]

elect yes it is , im a funny bugger like to do them seperate

 

[Des 56]

An insulation resistance test is done over the whole of the installation
It needs to be done on individual circuits only when a problem may exist

 

[electek]

Des 56 , yep , i'm aware of that but i was wondering how you would do IR test on a lighting circuit if asked to do so on the actual part 'p' assesment ?

Regards
Chris

 

[Risteard]

An insulation resistance test is done over the whole of the installation
It needs to be done on individual circuits only when a problem may exist

And if it is done on circuits individually then calculations would need to be done to ensure that the installation is satisfactory, i.e. 1/Rt = 1/R1 + 1/R2 etc.

The values in BS7671 relate to the installation/dis. board - not to individual circuits!

 

[WayneL]

And if it is done on circuits individually then calculations would need to be done to ensure that the installation is satisfactory, i.e. 1/Rt = 1/R1 + 1/R2 etc.

The values in BS7671 relate to the installation/dis. board - not to individual circuits!

Are you saying that if you IR tested six circuits individually, and they each gave a reading of 5 M ohms, the installation wouldn't comply, and you would fail it.

 

[Risteard]

Are you saying that if you IR tested six circuits individually, and they each gave a reading of 5 M ohms, the installation wouldn't comply, and you would fail it.

If below 2 Megohms then you would need further investigation, i.e. checking individual circuits. You already have the values for the individual circuits.

The point I was making was that the insulation resistance value is not just fo the circuit (read the Regulation carefully).

 

[WayneL]

If below 2 Megohms then you would need further investigation, i.e. checking individual circuits. You already have the values for the individual circuits.

The point I was making was that the insulation resistance value is not just fo the circuit (read the Regulation carefully).

I know, I'm just causing trouble - that's why the big cheesy grin

It's an interesting scenario, though, 'cause it gives an overall resistance of 0.83 Mohms for the installation, yet each individual circuit complies.