Earth Leakage Query.

[telectrix]

might be having a blonde moment here, but.... if an installation has earth leakage, could this be measured with an earth leakage clamp meter on the main earthing conductor and/or the main bonding conductors as logically, if there is leakage , you would expect the current to travel to earth through these conductors?

 

[topquark]

If you have dedicated use of the circuits/house you could try this, with the usual precautions. Isolate each circuit and check the main earthing conductor for leakage. Then engage each circuit one by one checking the leakage (the last one(s) to engage should be the RFC's as that's where most of the "good" leakage tends to be). That should give you a rough idea of how leaky the installation is likely to be.

That should give you an idea as to whether you want to investigate one circuit more fully before changing the CU or if there's a circuit that you don't want to RCD/RCBO protect, at least to start with.

If you had dedicated use of the house you could disconnect the main bonding as well (but there's an obvious risk to doing that ).

 

[pushrod]

if only. i have the alphatek tek633. the jaws won't close around 2 tails.

Get your mole grips out and squish them first :smilewinkgrin:

Sticking it on your main earth could give you an indication of possible probs and a definite all-clear if you are getting just a few mA when everything is on.

 

[telectrix]

Get your mole grips out and squish them first :smilewinkgrin:

Sticking it on your main earth could give you an indication of possible probs and a definite all-clear if you are getting just a few mA when everything is on.

exactly my tinking. if there's only, say 5 or 6 mA flowing through the main earthing conductor ( and/or the main bonding conductors ) then i would expect that all the circiuts were healthy. obviously, some circiuts could be breaking down under a load not present at the time, so that's why i stressed that it should only be a rough guide to help in deciding whether or not there might be issues when fitting RCD protection.

edit. didn't think of squishing the tails. bloody good idea. they would look better flat, saves buying round clips :yesnod:

 

[topquark]

Just had a quick check on mine 11.5mA (give or take) on both main earth and differential on live/neutral. That's on a PME based earthing system.

 

[pushrod]

Just had a quick check on mine 11.5mA (give or take) on both main earth and differential on live/neutral. That's on a PME based earthing system.

You're lucky mine is 40+ then my ELCM goes over range on the tails, on the bright side it's less than 0.1A :thinking: , but i've still got 40+mA in the earth when the whole installation is isolated, obviously a lot of investigation to do before i change my own CU.(that's on a tn-s)

 

[telectrix]

You're lucky mine is 40+ then my ELCM goes over range on the tails, on the bright side it's less than 0.1A :thinking: , but i've still got 40+mA in the earth when the whole installation is isolated, obviously a lot of investigation to do before i change my own CU.(that's on a tn-s)

wel that's an easy one. convert it to TT, that will incrfease the Ze, thus reducing your leakage current to a manageable level :carolers:

and noo commentz on the typos, jusd got back from the Polish Club, 110 proof vodska.

 

[tony mc]

tel

I had a board change last week and only had 7 mA leakage on the tails prior to doing a globle IR.

On testing I found that the up lights CCT was 0.00 Meg and when changed to ohms it was just over 99k ohms between Neutral and CPC.

Even with that reading the RCD will hold and no leakage was found when the tails were clamped the 7 mA was from the 2 ring finals.

I suppose ot would have to drop below 7666 omhs or there abouts.


Loads of faults at swiches neutrals nicked etc.

 

[topquark]

You're lucky mine is 40+ then my ELCM goes over range on the tails, on the bright side it's less than 0.1A :thinking: , but i've still got 40+mA in the earth when the whole installation is isolated, obviously a lot of investigation to do before i change my own CU.(that's on a tn-s)

When doing the tails clamp, then turn the meter on (or off/on again (whilst clamped)) and see if that makes any difference to the reading, I've noticed that some meters are a little too sensitive to being open/closed when on.

I did spend a little while getting to the bottom of all of my leakage before changing my CU. Most was down to the downstairs sockets (hence the suggestion to re enable them last). Tv/Sat/Surround sound/laptop/computer and a couple of Tvs on standby. Nothing out of the way but it does soon mount up.

 

[pushrod]

tel

I had a board change last week and only had 7 mA leakage on the tails prior to doing a globle IR.

On testing I found that the up lights CCT was 0.00 Meg and when changed to ohms it was just over 99k ohms between Neutral and CPC.

Even with that reading the RCD will hold and no leakage was found when the tails were clamped the 7 mA was from the 2 ring finals.

I suppose ot would have to drop below 7666 omhs or there abouts.


Loads of faults at swiches neutrals nicked etc.

I think the real advantage of using an ELCM is to check the appliances of the customer (it is not a substitute for IR testing) before changinging the CU so that you can identify the culprit(s) or at least warn the customer of what is going to happen. Otherwise on completion of the job you might hear those words from time immemorial "it was ok before you started working on it"!

When doing the tails clamp, then turn the meter on (or off/on again (whilst clamped)) and see if that makes any difference to the reading, I've noticed that some meters are a little too sensitive to being open/closed when on.

I did spend a little while getting to the bottom of all of my leakage before changing my CU. Most was down to the downstairs sockets (hence the suggestion to re enable them last). Tv/Sat/Surround sound/laptop/computer and a couple of Tvs on standby. Nothing out of the way but it does soon mount up.

Have tried that, unfortunately my house does have real issues and the wiring is pretty ancient in places; but the current in the earth, when the power is off, is the real puzzler.

 

[telectrix]

I think the real advantage of using an ELCM is to check the appliances of the customer (it is not a substitute for IR testing) before changinging the CU so that you can identify the culprit(s) or at least warn the customer of what is going to happen. Otherwise on completion of the job you might hear those words from time immemorial "it was ok before you started working on it"!



Have tried that, unfortunately my house does have real issues and the wiring is pretty ancient in places; but the current in the earth, when the power is off, is the real puzzler.

that's an easy one. you live in leicestershire, where it's as flat as a pool table. there ain't no hills for the current to run down. sssimples.

 

[topquark]

Have tried that, unfortunately my house does have real issues and the wiring is pretty ancient in places; but the current in the earth, when the power is off, is the real puzzler.

With only one supply, spooky perhaps your house is working as a large solar cell and with the power off it has no where else to go

Ignore me now, I've been on the vino again! :17: :54:

 

[pushrod]

[/COLOR]

that's an easy one. you live in leicestershire, where it's as flat as a pool table. there ain't no hills for the current to run down. sssimples.

LOL well that is as good as any of my ideas.

With only one supply, spooky perhaps your house is working as a large solar cell and with the power off it has no where else to go

Ignore me now, I've been on the vino again! :17: :54:

The best i could come up with was the house was acting as a giant capacitor:thinking:

 

[topquark]

LOL well that is as good as any of my ideas.



The best i could come up with was the house was acting as a giant capacitor:thinking:

Ah, but capacitors don't generate charge, they store it, well rather they allow a PD to be built between two dielectrics .... more beer needed !

 

[topquark]

Ah, but capacitors don't generate charge, they store it, well rather they allow a PD to be built between two dielectrics .... more beer needed !

No one was in the mood for taking the hiss then

 

[telectrix]

i have a healthy respect for capacitors, ever since working on 1970's colour TVs. when a section of the crude wire wound dropper resistor went o/c. there would be a nice 200v charge left on the smoothing capacitor. the usual method of discharging this before getting bit big style was to use a 10" blade pozidriv screwy. to s/c the cap. to chasssis. still got my old one with little blackened nibbles.