RCD Tripping Intermittently

[shanky887614]

I bought a really good unit - the Metrel MD 9270 - which wasn't cheap BUT does lots of things - so I had saved up to buy it and a mate had one!

What's a reasonably priced model that people would recommend? Something with decent accuracy on low readings. Daz

Another reason is the high hold feature, you can clamp it on a circuit and run an appliance for several minutes and record the max leakage during the time.

I'm sure you could get by without one if you really wanted to and you have a megger tester and RCD ramp tester but there are some occasions when they're the best tester for the job at hand and like you say, for the price of them nowadays, I can't see any reason not to carry one as standard equipment.

you can get a good one for £50 and they will soon pay for themselfs, test-meter stock them.

 

[richard1972]

do you use IR test majority of time and only use ELCM on intermittent tripping ? or is it quicker to use ELCM on permanent tripped rcd sometimes ? i want to buy ELCM but trying to understand how often i will use versus how much to spend

 

[Engineer54]

you can get a good one for £50 and they will soon pay for themselfs, test-meter stock them.

Only in your dreams!! 120-150 Quid is more like it!!

EDIT... just checked test-meter and they do the TEM for around a hundred notes, which if i were after a budget ELC, would be the unit i'd be looking to purchase!!

 

[Richo77]

Any one purchased the TEK 775 meter? They are about £70. Thinking of getting one. Are they any good?

 

[Engineer54]

Any one purchased the TEK 775 meter? They are about £70. Thinking of getting one. Are they any good?

You really need a higher resolution than that provided by the TEK775...

 

[Richo77]

Ok cheers E54

 

[telectrix]

Fair enough,I'll happily accept that some consider it essential. Not for me though,Just about every week I'll be dealing with an RCD tripping issue,and they rarely take long to sort out with just my IR tester and an RCD tester. Come the day when there's one I cant sort out and somebody comes in with an earth leakage clamp and does what I couldnt do then maybe I'll go out and buy one. But till then.....

funny enough, on a new install i have an intermittent RCD tripping. nothing plugged in. IR tests L-N >299Meg. L-E >299Meg, N-E >299Meg. ramp test 27mA. trip times normal @ 31mSec @ x1 and 11mSec @ x5.

 

[Deleted member 9648]

+1 why start disconnecting circuits and ir testing each one?

you shouldnt ir test the circuit with apliances plugged in anyway.

i would bet money that its probably the fridge or another appliance, its a lot easier to clamp the earth and then turn the breakers off to find where the most leakage is coming from and then go from there

I think it's clear from the replies from respected members that an ELCM is a useful addition to fault finding.I would dispute that it is essential based on the fact that I dont possess one and yet successfully rectify RCD tripping problems regularly week in week out in little time.
Why shouldnt you IR test a circuit with appliances plugged in? If I'm fault finding I want everything in place so that the fault is there when I test. Initially I unplug known sensitive equipment but leave everything else in place and do a 'soft' 250v test to begin with. It's rare that a 250v test wont show up an IR issue that a 500v test would,but if necessary I'll do a 500v test after double checking that there is no sensitive equipment connected.
I've also lost count of the times I've been called to intermittent tripping problems where another electrician has 'fixed' it only for the issue to continue. On nearly every occasion an IR test has identified a fault that the other electrician would have found if he'd IR tested correctly.
It's clear to me from the inumerable threads on this subject that the advise is always 'ramp or clamp'.
Even if I buy a clamp I'll still IR test before considering anything else.

 

[Octopus]

I think it's clear from the replies from respected members that an ELCM is a useful addition to fault finding.I would dispute that it is essential based on the fact that I dont possess one and yet successfully rectify RCD tripping problems regularly week in week out in little time.
Why shouldnt you IR test a circuit with appliances plugged in? If I'm fault finding I want everything in place so that the fault is there when I test. Initially I unplug known sensitive equipment but leave everything else in place and do a 'soft' 250v test to begin with. It's rare that a 250v test wont show up an IR issue that a 500v test would,but if necessary I'll do a 500v test after double checking that there is no sensitive equipment connected.
I've also lost count of the times I've been called to intermittent tripping problems where another electrician has 'fixed' it only for the issue to continue. On nearly every occasion an IR test has identified a fault that the other electrician would have found if he'd IR tested correctly.
It's clear to me from the inumerable threads on this subject that the advise is always 'ramp or clamp'.
Even if I buy a clamp I'll still IR test before considering anything else.

Really?

I test the RCD to check its functionality, then the clamp to check the "back ground" leakage, then IR - unless its abundantly clear one specific circuit is to fault!

 

[davesparks]

+1 why start disconnecting circuits and ir testing each one?

you shouldnt ir test the circuit with apliances plugged in anyway.

i would bet money that its probably the fridge or another appliance, its a lot easier to clamp the earth and then turn the breakers off to find where the most leakage is coming from and then go from there

You should clamp round the tails as a group not the earthing conductor, otherwise the result will be affected by the bonding and small currents which can circulate in the earth.

 

[Marvo]

The earth leakage tester I've found myself using the most is a very small, very light Chauvin Arnoux flexible clamp tester which isn't actually marketed as a leakage current clamp but it performs remarkably well with leakage currents as low as a couple of miliamps. Having a flexible clamp makes it very handy because it's easier to get it around multiple wires at once such as supply tails etc. It also has a remarkably good frequency range which means it's surprisingly accurate for most carrier frequencies of motors driven by a VFD and it would probably work will on lighting circuits supplied by a dimmer whereas many other clampmeters won't. A few other things in its favour are it's true RMS, it's got a high hold feature and you can switch off the auto power down so it can be left in a DB or panel overnight to record the maximum current event. Finally it was very cheap.

Here's the manual and data.
http://www.chauvin-arnoux.at/download/digiflex/ba_ma400d.pdf

Testmeter have it available on their website for 134 of you UK pounds (ex VAT) before forum discount. http://www.test-meter.co.uk/chauvin-arnoux-digiflex-ma400d-250mm-sensor/

 

[shanky887614]

The earth leakage tester I've found myself using the most is a very small, very light Chauvin Arnoux flexible clamp tester which isn't actually marketed as a leakage current clamp but it performs remarkably well with leakage currents as low as a couple of miliamps. Having a flexible clamp makes it very handy because it's easier to get it around multiple wires at once such as supply tails etc. It also has a remarkably good frequency range which means it's surprisingly accurate for most carrier frequencies of motors driven by a VFD and it would probably work will on lighting circuits supplied by a dimmer whereas many other clampmeters won't. A few other things in its favour are it's true RMS, it's got a high hold feature and you can switch off the auto power down so it can be left in a DB or panel overnight to record the maximum current event. Finally it was very cheap.

Here's the manual and data.
http://www.chauvin-arnoux.at/download/digiflex/ba_ma400d.pdf

Testmeter have it available on their website for 134 of you UK pounds before forum discount.

thanks marvo, ill buy it this month if i have missed out on the mft

(i haven't needed one yet cause we dont use rcd's day to day)

 

[Deleted member 9648]

Really?

I test the RCD to check its functionality, then the clamp to check the "back ground" leakage, then IR - unless its abundantly clear one specific circuit is to fault!

YES!! Really!
I've just seen so many jobs where a 'faulty' RCD has been changed only for the tripping to continue. I'm not knocking anyones approach just because it's different to mine,but one thing will never change....if I have a tripping RCD the first thing I will do is an IR test and eliminate that before any other tests. End of!

 

[telectrix]

YES!! Really!
I've just seen so many jobs where a 'faulty' RCD has been changed only for the tripping to continue. I'm not knocking anyones approach just because it's different to mine,but one thing will never change....if I have a tripping RCD the first thing I will do is an IR test and eliminate that before any other tests. End of!

NO, NO, NO !. that's the second thing. the first thing is to hit it with a hammer. :49:

 

[richard1972]

do you use IR test majority of time and only use ELCM on intermittent tripping ? or is it quicker to use ELCM on permanent tripped rcd sometimes ? i want to buy ELCM but trying to understand how often i will use versus how much to spend

anyone ?

 

[Deleted member 72666]

^^^^
Stop tormenting yourself , you'll never see this as a bad buy I guarantee it in fact you'll end up using it more than you think so go out and get yourself one you know it makes sense!

 

[Marvo]

anyone ?

I think your answers are already in this thread. The two methods of test are chalk and cheese really; IR is a dead test, ELCM is a live test. IR is measuring insulation values ELCM is measuring actual real-live leakage which is what the RCD is seeing. IR test uses a DC test signal so may not be an accurate reflection of leakage if there's appliances connected with internal surge arrestors. An ELCM can be used as a monitor over time whilst an appliance is running, an IR tester can't. An ELCM can monitor leakage across a live 3 phase supply, an IR tester can't. An global or single circuit ELCM test can often be made without interrupting the supply, an IR test can't.

There's also lots of advantages that an IR tester also has for certain tests but I'm sure you get my point which is that both testers have their place in your toolkit in my opinion although there are some people who maintain you can live without an ELCM if you have a megger tester and an RCD ramp tester. I'd concede you probably could live without one if you were stubborn as a mule and you're mind was made up but my argument would then be why risk making your life difficult when the cost of an ELCM is so low?

 

[Deleted member 9648]

I think your answers are already in this thread. The two methods of test are chalk and cheese really; IR is a dead test, ELCM is a live test. IR is measuring insulation values ELCM is measuring actual real-live leakage which is what the RCD is seeing. IR test uses a DC test signal so may not be an accurate reflection of leakage if there's appliances connected with internal surge arrestors. An ELCM can be used as a monitor over time whilst an appliance is running, an IR tester can't. An ELCM can monitor leakage across a live 3 phase supply, an IR tester can't. An global or single circuit ELCM test can often be made without interrupting the supply, an IR test can't.

There's also lots of advantages that an IR tester also has for certain tests but I'm sure you get my point which is that both testers have their place in your toolkit in my opinion although there are some people who maintain you can live without an ELCM if you have a megger tester and an RCD ramp tester. I'd concede you probably could live without one if you were stubborn as a mule and you're mind was made up but my argument would then be why risk making your life difficult when the cost of an ELCM is so low?

Lol....yes I'm as stubborn as a mule!
My first point here is that I've been fault finding RCD's for years quite alright thankyou very much without an ELCM,so they are hardly essential,useful I would concede and I should probably possess one,but essential no.
A second point is that from following these threads over the years it is apparent that many never even consider an IR test.I think thats a mistake. And I'll state again the numerous times I've gone to a replaced RCD still intermittently tripping and found a low IR.

 

[Marvo]

Lol....yes I'm as stubborn as a mule!

It was just a small dig

 

[richard1972]

I think your answers are already in this thread. The two methods of test are chalk and cheese really; IR is a dead test, ELCM is a live test. IR is measuring insulation values ELCM is measuring actual real-live leakage which is what the RCD is seeing. IR test uses a DC test signal so may not be an accurate reflection of leakage if there's appliances connected with internal surge arrestors. An ELCM can be used as a monitor over time whilst an appliance is running, an IR tester can't. An ELCM can monitor leakage across a live 3 phase supply, an IR tester can't. An global or single circuit ELCM test can often be made without interrupting the supply, an IR test can't.

There's also lots of advantages that an IR tester also has for certain tests but I'm sure you get my point which is that both testers have their place in your toolkit in my opinion although there are some people who maintain you can live without an ELCM if you have a megger tester and an RCD ramp tester. I'd concede you probably could live without one if you were stubborn as a mule and you're mind was made up but my argument would then be why risk making your life difficult when the cost of an ELCM is so low?

thanks marvo.

i understand they are different, and from reading the posts, it seems that on an intermittent trip scenario, they would be very useful. im just trying to understand when and how i/you would use ELCM and how it would speed up finding fault

on a permant fault rcd tripped, you can find fault using IR test ( how would/could a ELCM make things quicker )

sorry if im being particular, but im just trying to work out how much to spend versus how much would/could use