- Reaction score
- 380
Hi HS,
I find clamping the Earthing conductor misleading, as often you can measure more mA than it would take to trip a 30mA RCD even in a correctly functioning installation.
I wonder if this reading is actually imported ?
A better test is to clamp both tails as this shows how much leakage is present in the installation.
I often do this prior to a CU change, as any significant readings here shows that you will have to test much further before the change, as you are likely to have problems once RCD's are fitted.
Presumably the reading you get by clamping the Earth is the cumulative total of leakage from all circuits not just one circuit, so I guess if you had an upfront RCD then this total could tip it over the edge, depending on the mA, if the leak was <mA setting over several circuits, it shouldn't trip the RCBO, unless of course it was leaking like a sieve lol. Out of interest,could someone tell me if you can clamp a T&E Radial or half leg of a RFC and get a mA reading, or do the cpc and L/N need to be separated ?
ATB J