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.

 

[pushrod]

if its pme it may be some diverted neutral current.

Regards chris

hi chr!s, care to expand on this?

 

[topquark]

hi chr!s, care to expand on this?

That's got my curiosity too!

 

[telectrix]

think it's electron confusion as the E and N are connected together at the head, the poor little buggers don't know which route to take.

 

[topquark]

think it's electron confusion as the E and N are connected together at the head, the poor little buggers don't know which route to take.

Tel has discovered a new quantum effect: Indecisive electrons

 

[telectrix]

they were fine when they were using a map and compass, but now they've been supplied with a sat.nav. that's what's buggered the poor little sods. they want to take the neutral path, but the sat.nav. directs them down the earth path, even though it's clearly marked as " no through road for electrons".

 

[topquark]

They'll be inventing duality next so they can go both ways at the same time just to confuse us.

 

[telectrix]

the really confusing issue is when the positrons decide to intervene. a traffic jam at the junction would ensue, causing road rage and the release of megajoules of energy, this could result in a massive meltdown of the supply cable and so we could all have the rest of the day in the pub

 

[wade88]

ah but thats where the sub atomic particle police turn up and arrest all the rowdy particles and throw them in a capacity for the night until they find a use for them...

 

[telectrix]

use to be called a cell block, but now it's a custody suite with CCTV cameras in the bogs. wonder what the new name for a cess-pit is now. excrement suite? , poo parlour?

 

[Chr!s]

hi chr!s, care to expand on this?

Hi Pushrod

Well as Tel has already stated, becuae of the PME link the neutral current has a several paths, now dependent upon the CNE/PME impedance and the impedance of the protective conductors to earth, then you will find that some diverted neutral current will flow through the protective conductors.

The diverted neutral currents may be from your installation or even a neighboring installation.

Place a amp clamp around the live conductors at the origin on a TNC-S and see what leakage is present,and what the RCD will see.

Now dependent upon current, place a clamp/leakage clamp around the Earthing conductor and then other protective conductors.

See what you find

 

[topquark]

Oooh, now that's a tease. Are you suggesting that the imbalance in the live/neutral won't be reflected in the main earth for the instalation? That's nothing surprising because of the other extraneous paths, why is this more prevalent with PME? I feel like I'm missing something now

 

[telectrix]

i think the answer lies in a piece of toast. have you noticed, every time you drop a piece of toast, it always lands butter side down.

 

[kung]

650 meg is a great IR reading !

 

[telectrix]

and here was i thinking we'd got nicely off topic.

 

[topquark]

650 meg is a great IR reading !

And how many meters go that high? I suspected it was 650Ohms not MegOhms.