RCBO not restting

[TJ Anderson]

Yes most of the time even at 250v IR faults would show but your not appreciating dialectric properties of materials here, insulation breakdown is not linear therefore you cannot say that 250v IR test would expose a issues proportionally as that of a reading using 500v. It may be the case that the issue can only be detected at say 300v and remain undetected below that, this could lead to a false positive if testing on 250v, the value may show lower than expected but well within concerning values but at 500v you may see a significant breakdown in IR.

Even though many IR issues can clearly be identified at both test voltages due to the severity it remains the case that you can have a breakdown occuring at only close to peak voltages, now in the days before rcd's were thrown at every situation this would just be a matter of time before the breakdown got worse to cause noticable problems and a sparky called in, rcd's now have such sensitivity that adding general background leakage of devices its possible for the rcd to be sensitive to say 5-10mA of a fault where the rest is made up of electronics goods and other designed leakages, this in itself can make for a device able to pick up peak only issues that cannot be detected at a lower test voltage, also to note is the conductor temp' - because you are not really putting any current down the cable the conductors will not be subject to the same conditions as when loaded so the 500v also compensates for this too.

That is not practical or indeed necessary. Why would you need to note conductor temperature and compensation for this particular fault in a home. The cable is not loaded, it is dead and won't reset. That is totally OTT and you don't need to for this one. You should appreciate that the fault impedance we are talking about here is the region of 7666 ohms. Initially, 250V range would pick this fault up, and you can identify faulty circuit and subsequently the fault itself far quicker and without the issue of isolating vulnerable equipment. You have even said yourself above "Yes most of the time even at 250v IR faults would show" so why even bother with all this, it is just overcomplicating and confusing for the OP, who I also appreciate is probably long gone now

 

[PEG]

I can see TJ's argument,for many occasions,in a domestic testing environment,but that does not alter the fact that Darkwood is correct. It boils down to absolute electrical fact,not supposition. There are many installations where ONLY being there,and therefore in possession of ALL information,is vital to knowing what results are acceptable,or suspect. We all know,for example,GN3 states minimum values for IR testing,that could be cause for concern on at one job,and perfectly fine at another......now shake hands,and have a nice game of scrabble...:icon12:

 

[TJ Anderson]

I can see TJ's argument,for many occasions,in a domestic testing environment,but that does not alter the fact that Darkwood is correct. It boils down to absolute electrical fact,not supposition. There are many installations where ONLY being there,and therefore in possession of ALL information,is vital to knowing what results are acceptable,or suspect. We all know,for example,GN3 states minimum values for IR testing,that could be cause for concern on at one job,and perfectly fine at another......now shake hands,and have a nice game of scrabble...:icon12:

We are only debating, no problem. We can all quote electrical theory, it is how you apply to a given situation that matters.

 

[Geordie Spark]

I can see TJ's argument,for many occasions,in a domestic testing environment,but that does not alter the fact that Darkwood is correct. It boils down to absolute electrical fact,not supposition. There are many installations where ONLY being there,and therefore in possession of ALL information,is vital to knowing what results are acceptable,or suspect. We all know,for example,GN3 states minimum values for IR testing,that could be cause for concern on at one job,and perfectly fine at another......now shake hands,and have a nice game of scrabble...:icon12:

Sod the Scrabble lark ...... shove them both ootside and let them beat the shyte oot of each other!! :45::boxing_smiley:

 

[Darkwood]

We are only debating, no problem. We can all quote electrical theory, it is how you apply to a given situation that matters.

Yes! very good point for all the readers, its debate and the fact we respond like we do is presidence to our experience and understanding and enjoy the debate, so don't get my responses as a challenge on your competence as its what this site is about but regarding this particular issue and the comment about 250v been sufficient Ill still stand ground as we went off the OP's particular query with the respective posts and that's why I got a bit deeper, and realise you also test at 500v and hence this is just a personal debate but with regard I'm trying to show the reason for 500v testing of IR.... If there exists even a 1% false positive testing at 250v then it justifies the use of 500v, most cable is rated 750v - 1000v so no reason at all as some posts do to suggest that 250v is acceptable ... I've laid my ground for my argument and in most you have technically agreed we me but still back up yourself for your own argument to which you now confuse me, yes as a percentage it may not be likely but the regulations for testing IR voltages exist because all what we debate has already been debate and agreed... PS drunk dot com.... apologise tommorow if this is BS lol ..

 

[Geordie Spark]

Yes! very good point for all the readers, its debate and the fact we respond like we do is presidence to our experience and understanding and enjoy the debate, so don't get my responses as a challenge on your competence as its what this site is about but regarding this particular issue and the comment about 250v been sufficient Ill still stand ground as we went off the OP's particular query with the respective posts and that's why I got a bit deeper, and realise you also test at 500v and hence this is just a personal debate but with regard I'm trying to show the reason for 500v testing of IR.... If there exists even a 1% false positive testing at 250v then it justifies the use of 500v, most cable is rated 750v - 1000v so no reason at all as some posts do to suggest that 250v is acceptable ... I've laid my ground for my argument and in most you have technically agreed we me but still back up yourself for your own argument to which you now confuse me, yes as a percentage it may not be likely but the regulations for testing IR voltages exist because all what we debate has already been debate and agreed... PS drunk dot com.... apologise tommorow if this is BS lol ..

So just to cut to the chase, are you two now agreeing that your schlongs are both the same size??

 

[Darkwood]

So just to cut to the chase, are you two now agreeing that your schlongs are both the same size??

Its been a battle of wit I must agree but the only thing I learned tonight is do not sneeze with a mouth full of poppadoms :dunce2: .. my laptop is a complete mess :uhoh2:

 

[Geordie Spark]

Its been a battle of wit I must agree but the only thing I learned tonight is do not sneeze with a mouth full of poppadoms :dunce2: .. my laptop is a complete mess :uhoh2:

I have a nice Karcher Powerwasher I can lend you to clean it.