Earth leakage help

[Duane B]

Hi guys. n gals lol

Got an issue with some operated 13a plugged machines tripping out rcbo's on the ring. 

What's best practice for checking earth Leakage.   megger type or equivalent meter clamped around the cpc earth only. 

 

[Sidewinder]

@Canoeboy, I think we have the Di-Log DL6507 one, I have a Megger DCM300E also.

Ampsayman, don't clamp the earth, clamp both live conductors.

 

[steptoe]

I for mine from @megger mark also,

iirc its a di-log 6518

Gets used regularly, great little tool for pre-testing CU changes,

 

[Duane B]

Great stuff guys. megger seems way high. clamp both live conductors. phase & neutral .  ??? thought just leakage to earth was best for checking ????. 

 

[Sidewinder]

If you can measure all leakage then yes, but, how are you going to measure all leakage if you only clamp the cpc?

 

[Doc Hudson]

 thought just leakage to earth was best for checking

Pretty much every installation has parallel earth paths once all bonding is in place. Consider a scenario where your leakage problem is finding an easier route to earth without using the bit of the CPC where you have your clamp meter. Or is sharing its path with your bit of CPC and two other parallel routes. So unless you clamp every possible earth path you will not be reading the full leakage current. Whereas the current difference between the two live conductors will be the total leakage whichever path it is following to earth.

Doc H

 

[Kurt]

agree with above, no point clamping the cpc. You need to clamp what the RCD is seeing, i.e. difference between L and N

 

[Murdoch]

Have you properly tested the RCD? Could be a goosed RCD!