Insulation resistance test

[1983]

Hi all on a eicr insulation resistance test between live conductors to earth gn3 says join l & n and test to earth is there any difference between that and testing phase to earth then neutral to earth? As you guys know some boards are a right mess and not in order to locate which belongs to which

 

[Strima]

The idea of linking L&N and testing to earth will allow you to do a global test quickly. If it passes on the global then all is good, if not then you need to break it down into circuits to find the culprit.

 

[1983]

So would you say that testing l then n to earth is individual

 

[westward10]

So would you say that testing l then n to earth is individual

I rarely connect them together but the theory is if you do it may eliminate possible damage to sensitive electronic components.

 

[Richard Burns]

If you test L to E or N to E without disconnecting all loads then you apply 500V DC to the internal components of any load, in general this might be OK and will not cause harm however in some cases (such as smoke alarms, as they always say do not IR test)) the components may not be rated for that voltage and may fail.
If you join L and N together then test to earth then there is no potential difference across the internal components.

 

[1983]

When I do testing in occupied houses most are in a mess all over the place trying to find which point belongs to which circuit is a headache so when it comes to testing I seem to always get funny readings coz of loads connected still so go round unpluging what not some u just can't seem to find

 

[1983]

I always go with 230 1st until I get good reading then the 5

 

[1983]

Sorry of topic but wanted to get your guys views on something an old boy sparks once told me tns system is better then pme would u agree

 

[westward10]

There are pros and cons to both, TN-C-S can cause problems with the loss of neutral and on the reverse side many TN-S supplies are derived from older cables and can suffer from earth loss through degradation or network alterations.

 

[1983]

Thank you mate makes sense. Got another question for you if you don't mine was testing a ring only four points on it r1 0.11 rn 0.13 r2 0.70 can only access two points as the other to needs hours just moving to many things about checked the two sockets and ccu no lose connection

 

[westward10]

Your R2 seems high in relation to the line continuity.

 

[1983]

That's what I mean so I got no choice but to check connections on the 2 remaining sockets which means moving a lot of stuff

 

[westward10]

What needs moving just sheer junk or furniture.

 

[1983]

Junk on top of furniture on one side and massive walldrope on the other with more junk was thinking to just drop the mcb size to 20 amp

 

[westward10]

Dropping it to 20A won't solve a possible earth continuity fault. As you are doing an EICR I would not be over concerned at finding the fault, Code it in the Report and if you are asked to do remedial works then advise the client access is required.