Earth leakage clamp meter

[a-z electrics]

The TEK775 has a resolution of 100microamps (ie 0.1 mA) on the 200mA range with a 5%+/- accuracy. I didnt think this was bad for general domestic use but I would be happy to be overruled by our more experienced members.. I guess like anything else, you get what you pay for.. if you need greater accuracy then you pay more.

 

[44ALLAN]

I'd post this in the trainee section if I had access (but I don't). I understand on the basics on why the "circulating earth currents" are there, but not fully grasping why they are not dangerous and not corresponding to a shock hazard off bonded metalwork etc.

In the spirit of the forum, I don't expect to be spoon fed the answer, but if someone could start me on the right track I'd be massively grateful.

DJ..................you have almost answered the question yourself mate...........think about it.
Bonded metalwork/touch voltages/extraneous parts.

Also..............they(currents) are not only dangerous but lethal.............don't ever think differently mate.

 

[DJ Ovengloves]

Thanks Allan.

I understand why in the present configuration there is no shock as the current is flowing straight to Earth via the main Earth bond and Main Equipotential bonding (mainly the Gas according to my clamp meter). I was / am struggling on what would happen if I was stupid enough to remove the Bonding and Earth cables - for instance, would class one fixtures become live?

Anyhoo, after a bit more of a thought time, this is what I think is happening.

Due to the nature of PME, it's common for these Circulating Earth Currents that are present on the local "PME network" (sorry, I don't know the real term) to "enter" the installation as electric is lazy and can see nice and easy return path back to Earth. In the Event the main Earth and Bonding being removed within the installation, the Circulating Earth Currents will simply sod off somewhere else with a better path to Earth (hence the need for "Protective Multiple Earthing" for TNC-S, to ensure there's always and "easy path" for these currents and broken DNO Neutral etc).

Does that seem plausible / make sense / correct?

DJ..................you have almost answered the question yourself mate...........think about it.
Bonded metalwork/touch voltages/extraneous parts.

Also..............they(currents) are not only dangerous but lethal.............don't ever think differently mate.

 

[44ALLAN]

Bit early for me all that lot lol'
Still got a nice 'real ale' head on mate

"I was / am struggling on what would happen if I was stupid enough to remove the Bonding and Earth cables - for instance,"

Basic here mate and you work the rest out...................

Remove earthing............nowhere for fault current(or circulating current) to go.
Remove bonding..............introducing extraneous parts and dangerous touch voltages between equipment and metalwork ( no equipotential zone).

I should read that back before posting it in case I've dropped a 'cod' but I'm sure someone will correct it for me lol

Back to bed ...................zzzzzzzzzzzz