lightweight EFLI tester?

[ecowarrior]

I am trying to find a small lightweight EFLI tester. I am HVAC and want to get into the habit of checking this at the boiler input. Some of the newer boilers need functional earths and I wasted no end of time recently - not doing proper basic checks. I have a ELFI multi meter but its to big to be practical with the rest of the gubbins I have to hump about. I saw a Suck it & see plug that claimed this - so one option may be to attach 3 leads to this - but any options gratefully received

 

[ericmark]

First this is a DIY forum please state what letters are somewhere in the text. Earth Fault Loop Impedance (EFLI) can be to some degree tested with both the MartinDale

socket & see

and Kewtech

plug in testers but as electricians we need to enter the values into the paperwork so are not really any good for what we are doing.

As a result very few of us will have tried using these units. As a Heating Ventilating and air conditioning (HVAC), I assume not High Voltage Alternating Current?, posting in the Plumbing and Central Heating section may get better results for people doing the same thing.

I would have thought by time you have a socket and wandering leads it would be as big as a unit to a proper loop tester and what would worry me is the lack of test buttons on some of these testers which could lead to ionisation i.e. a big bang.

 

[ericmark]

Your question has got me thinking. Non of the testers I have shown seem to have a test button. Normally when we put leads onto anything to test we draw no current but to test Earth Loop Impedance is an odd one out where we do draw current. As a result bad connections can on the odd time ionise the atmosphere which makes the atmosphere conduct as happens when we watch a thunder storm. I would guess the testers have a delay before some internal switch makes which as a socket tester is OK. But if used with wandering leads could be very dangerous.

Please don't try using any of these testers with wandering leads.

 

[ecowarrior]

Thanks for your time! I have looked now at the martindale one -and hey look at this: http://www.tester.co.uk/martindale-ez650-socket-tester-kit-with-earth-loop-test

I dont need to write results as its just a basic test to see that it has more than an 'earth' but a 'proper' earth. I had an issue with a TT system in a pub - new fancy boilers -new fancy software - but nothing doing what it should. Turned out the earth was over 300 ohms & the software didn't like it. I am pretty sure it was responsible for the big plasma's playing up which made me look again at more obvious things.
This is my main weapon of choice for the electrics I usually need:
http://www.kewtechcorp.com/products/electrical-testing/kew1700 -
checking voltage polarity & earth but it let me down this time.
I am aware of the three impedance required for the 3 earthing systems & just need to ensure they are 'about right' and that the software should function correctly. This fancy martindale plug jobbie looks the ticket - would appreciate your opinion?
as for posting on the plumbing section - r u avin a larf? They dont know part p is here - let alone it is going (to all intents & purposes) come April

 

[333rocky333]

You could buy a cheaper set of these

http://isswww.co.uk/Test-Leads/Fluk...rce=googleps&gclid=CMnEh5q78rUCFabLtAod8nEAYA

Chop the plug off and fit a trailing socket and tester just plugs in

http://www.tooled-up.com/product/sm...oductlisting&gclid=COfHh_S78rUCFaLHtAodCkQAtg

you may want to read this, it actually recomends the EFLI versions over the standard type

http://www.socketandsee.co.uk/pdfframe.asp?type=1&ProductID=1917

 

[333rocky333]

Please don't try using any of these testers with wandering leads.

Dont most EFLI testers and RCD testers even the ones with buttons, come with wander leads and an auto test facility, which is activated when the probes make contact, thus eliminating the need to press the button.

 

[EFLImpudence]

Please don't try using any of these testers with wandering leads.

Dont most EFLI testers and RCD testers even the ones with buttons, come with wander leads

I wouldn't call them wander leads but - leads, yes.

and an auto test facility,

Not all.

which is activated when the probes make contact, thus eliminating the need to press the button.

No.

 

[ericmark]

I have come across PAT testers which will not work when the earth is a little on the high side but the limit is 50 volt and with a 30 ma RCD that 1666 ohms although we would normally consider (Table 41.5 Note 2) that 200 ohms is the limit so more like 6 volt that the earth will vary from neutral voltage.

The maximum leakage allowed without special earthing arrangements is 3.5ma (543.7.1.1) which with the maximum earth loop impedance is 5 volts so although 50 volts may be the official limit in real terms just 10 volts.

As to what the limit is with the boilers I don't know but if you stick a standard AC volt meter between earth and neutral and it reads more then 10 volts then I would say "Sorry there seems to be an earthing problem the system needs testing before I proceed further." There is really no need for an earth loop impedance meter just a simple voltmeter.

I can see why a PAT tester would refuse to run with an earth problem but I just don't know why a boiler has an auto shut down with an earth fault? In real terms if I wanted to run a boiler off a IT system then that's up to me. Not the boiler manufacturer.

The only reason to connect anything on a circuit board to earth is for the spike protection. There are places where diodes are placed between earth wires giving a 1.2 volt or more thresh hold before any voltage is leaked away. All to do with cathodic protection so I would say any boiler should allow at least 2.4 volt before any shut down is enacted.

Allowing for volt drop 3 to 10 volts is quite acceptable where 30ma RCD's are used. At 10 volt to 50 volt although it would likely pass I would investigate further. Over 50 volt of course is where you recommend switching off until corrected.

As tradesmen both gas and electric we have to be very careful. If we make a home uninhabitable it is up to us to find alternative accommodation. So I am careful always to get permission to turn off power. Also if I do find a fault I tell occupants I am not permitted to restore power but can't stop them doing it once I leave. Never remove things to stop them restoring power. Hotel bills can be expensive.

 

[ericmark]

As a PS I did look at the devices you selected. One said it did phase rotation yet single phase. There is no phase rotation on a single phase supply so I don't trust anything else it says.

 

[Spark123]

The kewtech one? If so it is a voltage indicator suitable for 3 phase supplies, the indicator of rotation just shows the relationship between the two phases under test. Some of the fluke Voltage Testers have the same function.

 

[ecowarrior]

The maximum leakage allowed without special earthing arrangements is 3.5ma (543.7.1.1) which with the maximum earth loop impedance is 5 volts so although 50 volts may be the official limit in real terms just 10 volts.

As to what the limit is with the boilers I don't know but if you stick a standard AC volt meter between earth and neutral and it reads more then 10 volts then I would say "Sorry there seems to be an earthing problem the system needs testing before I proceed further." There is really no need for an earth loop impedance meter just a simple voltmeter.
o

Sometimes u need someone to help u step out the box - yes a bit of simple maths & u have my answer. I also have no idea how big an earth issue mucks up the boilers as it only affects a few & i have only come across it knowingly on one occasion.

There is obviously a direct relationship between the loop impedance & the volt drop across N & E do u have the time to explain that please?

Thankyou all - for your constructive answers.

 

[martinxxxxxx]

Thanks for your time! I have looked now at the martindale one -and hey look at this: http://www.tester.co.uk/martindale-ez650-socket-tester-kit-with-earth-loop-test

That Martindale has 3 LEDs on it indicating 0-1Ω, 1-10Ω and 10-100Ω. for EFLI. I brought one, compared it against my calibrated MF tester and it was nowhere near, most sockets it claimed were under 1 Ω, however some sockets it put in the 10-100Ω which measured less that 1Ω.
It also reported many healthy circuits as having no earth.
So I sent it back and got another one, after the third one I got a refund.
Moral of story - Make sure you buy it from somewhere with a decent returns policy and don't panic if it says your installation has no earth - actually just don't buy it

 

[ericmark]

At the transformer neutral and earth are connected together the impedance is the resistance of the wires and earth between the transformer and where being measured.

Since the earth should have no load and the neutral has load as current is draw the neutral voltage will go towards that of the line but the earth will say as it is at transformer so measuring the current and voltage with ohms law gives impedance (resistance) so by measuring the voltage difference between neutral and earth for a known load we can work out resistance.

For what you are doing you say you don't need the figure in ohms so to consider if within 10 volt is likely good enough for your needs.

 

[333rocky333]

Just a thought , are there any Gas regulations that may prevent you probing Live circuits in the vicinity of Gas

 

[ecowarrior]

Just a thought , are there any Gas regulations that may prevent you probing Live circuits in the vicinity of Gas

No!

You may notice when doing your training ( assuming it be one of those converted warehouses training every trade from brain surgeon to plasterer in 6 weeks) that u sparky guys stand on a 1" rubber mat wearing hard hat, goggles, ear muffs, jock strap, wellies & rubber cloves with GS whatever fused leads plugged into a grands worth of tester. You will have padlocked from the main door down to the light switch & safe isoilated the building from the grid. You will be encircled with 'do not come near me as I am a sparky' signs

Meanwhile - next door the plumbers are learning to check S plans on a 2.99 multimeter with the instructor saying 'try to remember not to lean on the case of the boiler when testing'. After a few sparks & a handfull of fuses comes the line we all need to hear. Congratulations u have passed your Part P & are now a qualified electrician. Join Ellecsa - give the inspector a biscuit with his tea and he will sign u up as full scope. You will then be competent to rewire houses & replace old consumer units.

I think that about sums it up?

Thankyou all for your time. I will stick to the 10 volt approach.