what causes earth leakage?

[ExArmy]

testing a house today before I put RCD protection on it and i got 300mA earth leakage. appox 100mA from the sockets, 180mA on the downstairs lighting circuit, then 20 odd mA accross the rest of the circuits.

I had a poke around the downstairs lighting circuit, couldn't see anything obvious, did R2 tests at all points (OK), did IR test and it was in the region of 650MΩ L-N, L-E and N-E.

as for the sockets, 2 chest freezers that are older then me are the cause of 50mA between them, rest is unnacounted for?

what causes this?

 

[topquark]

There are a number of devices that may cause leakage. For example anything that involves a power supply, transformer, heating element. First step should be IR test on the circuit (all devices disconnected and protect any vulnerable equipment) to elimate any faults with the wiring (often the cause of relatively high leakage, like you appear to have).

 

[topquark]

I should add that some of this can be considered (arguably) valid leakage, although it's undesireable. A typical personal computer for instance would leak less than 5mA in healthy condition.

 

[Deleted member 26818]

I allow 3.5mA for computers, although many are lower.
If the earth leakage is above 10mA on any circuits, you should be using high integrity earth connections for those circuits.

 

[telectrix]

how have you measured this 300mA leakage? that's a hell of a leak, worse than my local plumber!!!

 

[pushrod]

Suspect something is a bit wrong somewhere. A few mA here and there is ok with some devices but 300mA ???

Filters are devices in electronic systems often made from resistors, inductors and capacitors that control the form of input waves and as a result will of leak very small currents to earth but this is usually < a few mA.

A resistance of approx 766Ω between a Line and earth would give you 300mA of current in the cpc. I would be looking at dodgy appliances and low IR readings

 

[aptsys]

180mA on the downstairs lighting circuit,

40W light bulb connected L-E??

 

[malcolmsanford]

OP said that R2 was done so would have thought that there was no reversed N-E polarity in the circuits if all were done.

 

[Electro-tech]

What type of supply & Earthing arrangement?

 

[Chr!s]

if its pme it may be some diverted neutral current.

Regards chris

 

[Knobhead]

What causes earth leakage?

Magma finding it’s way through the mantle.

 

[mayfair]

You need a new flux capacitor.....me thinks

What causes earth leakage?

Magma finding it’s way through the mantle.

 

[telectrix]

pity we can't harness the power. would beat sunshine panels hands down.

 

[davelerave]

What causes earth leakage?

Magma finding it’s way through the mantle.

hilarious

 

[ExArmy]

suppy is TN-S, and it was measured using an earth leakage clamp meter.
since looking at the lights i've been told theres more lights and sockets that have been spurred off the downstairs lighting circuit in another part of the house, so when i go back i'm fairly confident I'll find the problem.