How to test earth leakage

[the pooks]

I am not an electrician but would nevertheless understand what the normal procedure is to test earth leakage / isolate an earth leakage problem.

One way is to switch all the switches off at the main DB board, switch them on one by one and see which one triggers the earth leakage circuit breaker (ELCB). Trouble with this is, in my case the ELCB only tripped after several minutes. I eventually narrowed the problem down to a certain freezer.

Another way is to use a clamp on earth leakage current meter. As I understand this is just a super sensitive current meter that can read in the range of milliamps. My questions is: does one clamp the meter over the live and neatral of a circuit (to measure any imbalance) or does one clamp over the earth (which can be tricky in a DB board). It should give the same result as any imbalance live/neutral imbalance is supposed to go to earth. What is the normal procedure.

Thanks

 

[yellowvanman]

You clamp it over the earth cable, to measure the earth leakage.

Not sure how thats going to help beyond what you have done already.

 

[topquark]

As yellowvanman says for usage. However bear in mind that a trip can be caused by a cummulative effect from more than one appliance/device. That's why you would normally ramp test the rcd to establish at what current it's tripping. Then try to account for that leakage current from each circuit (if the rcd covers more than one circuit) then down to each appliance/device. Hope that helps.

 

[the pooks]

Thanks guys, for taking the trouble to reply. Gives me stuff to work on.

 

[Engineer54]

As yellowvanman says for usage. However bear in mind that a trip can be caused by a cummulative effect from more than one appliance/device. That's why you would normally ramp test the rcd to establish at what current it's tripping. Then try to account for that leakage current from each circuit (if the rcd covers more than one circuit) then down to each appliance/device. Hope that helps.

Trouble with ramps tests, is that they are only an indication as to area of trip level, as very few test instruments ramp up in 1mA stages, but rather in multiples of anything from 3 to 5mA. The only accurate means of knowing the trip level and or actual leakage currents in a circuit is by use of a mA clamp meter....

 

[topquark]

That's what I'm suggesting he does in my forth sentence???

 

[i=p/u]

hi all, aint hijacking are these meters expensive???? or am i hijacking any links to quality brands??

 

[topquark]

hi all, aint hijacking are these meters expensive???? or am i hijacking any links to quality brands??

No, you can get one that'll do milliamps AC/DC for about £85 quid (or less if you shop around).

 

[Des 56]

am not an electrician but would nevertheless understand what the normal procedure is to test earth leakage / isolate an earth leakage problem.


Clampmeters aside

Insulation resistance testing is the standard means of testing for earth leakage
Clampmeters can identify the quantity and give good indicators,but they dont tell you why that leakage has occured


Use an insulation resistance tester before clamping

 

[i=p/u]

is this a maintance baby Extech MA-200 400A AC Clamp Meter#

 

[i=p/u]

.....................

am not an electrician but would nevertheless understand what the normal procedure is to test earth leakage / isolate an earth leakage problem.


Clampmeters aside

Insulation resistance testing is the standard means of testing for earth leakage
Clampmeters can identify the quantity and give good indicators,but they dont tell you why that leakage has occured

so what kind of reading would you expect doing insulation resistance on circuit with leakage... maybe im asking a wrong question. is it just a low reading??? cheers


Use an insulation resistance tester before clamping

 

[topquark]

am not an electrician but would nevertheless understand what the normal procedure is to test earth leakage / isolate an earth leakage problem.


Clampmeters aside

Insulation resistance testing is the standard means of testing for earth leakage
Clampmeters can identify the quantity and give good indicators,but they dont tell you why that leakage has occured


Use an insulation resistance tester before clamping

IR is for when you don't know you have a problem Des (it lets you know you have a problem). He knows he has a problem and is now trying to find it (the second stage).

 

[topquark]

is this a maintance baby Extech MA-200 400A AC Clamp Meter#

It has the resolution required. But may not have the low end range needed 0-30 milliamps. You need something that uses hall effect to register low currents, not just transformer based technology which typically starts at a higher current. It's ok having the resolution but no good if the range starts at say 10A min.

 

[topquark]

This is what I had (it's gone walkabout somewhere): Alphatek TEK633 3 in 1 200A AC/DC Clamp Meter. Buy online or call

Not advocating buying it from there (you'll find it cheaper).

 

[topquark]

As an example where IR testing won't help, take this (recent scenario).

Worktop cooker connected to ring with an element starting to fail (only shows when element under stress (heating up)). IR tests are fine on static circuit. Even earth leakage is minimal (below rcd threashold) when worktop cooker just turned on.

Even PAT testing the cooker didn't help.

 

[Engineer54]

I like this one as a good all round budget leakage tester
Dilog DL6507 10uA to 60A AC Leakage Clamp meter. Buy online or call

 

[i=p/u]

very good links guys. on me tool list which one i dont know

 

[topquark]

I like this one as a good all round budget leakage tester
Dilog DL6507 10uA to 60A AC Leakage Clamp meter. Buy online or call

That'll be on the shortlist for a replacement one; if it doesn't turn up in the van somewhere!

 

[topquark]

On reflection, I think I agree that IR testing is the correct method for any passive system testing ... and that earth leakage detection should be used for an active system. If that makes sense?