meggers

[Martin]

Re: meggers

leavemetogetonwithit wrote:Can we try and establish what my legal obligations are and take it from there? Gotta be a happy medium somewhere. Really don’t want to end up taking responsibility for the customer’s total electrical installation!
Mike.

I think we kinda covered that on page 4 of this thread Mike? Domestic Appliance servicing overall has no clear regulations to uphold other than to being sufficiently conversant in electrical safety. Conversant and able to show a ‘duty of care’ toward your customer for ensuring the appliance you fix is safe to use.

If, in the process of that repair you also notice that the wall socket and/or household electrical supply is faulty that duty of care then extends to at least informing your customer both verbally and in writing what you think the problem might be and the potential dangers of ignoring any advice given.

[lee8]

Re: meggers

And if your a gas tech, then you`ll need a second brain.

[leavemetogetonwithit]

Re: meggers

Martin wrote:

If, in the process of that repair you also notice that the wall socket and/or household electrical supply is faulty that duty of care then extends to at least informing your customer both verbally and in writing what you think the problem might be and the potential dangers of ignoring any advice given.
Sorry to drag this on again but that (in bold) sounds somewhat different from the more proactive stance of going in with a loop tester which several of you advocate. I’d be quite happy with a limited check on the supply socket which won’t take very long and which ought to be possible to do somehow without dragging round another meter*. I’m not a qualified electrician and I don’t think I should have to concern myself with the supply unless I spot something odd. * When I check the earthing of the appliance, I use my digital multimeter on the low Ohms scale which is passing only a tiny dc current. If that is acceptable, then why do I need to employ something rather more sophisticated on the supply? Having only used a small current to test the appliance earth, I don’t know for sure that it would carry a large fault current without breaking down, do I?
Mike.

[Martin]

Re: meggers

leavemetogetonwithit wrote:When I check the earthing of the appliance, I use my digital multimeter on the low Ohms scale which is passing only a tiny dc current. If that is acceptable,

I explain in my Megger Test.pdf the purpose of an insulation tester and it’s relationship between a low voltage earth check and a high voltage earth resistance check on the appliance. Digital multimeters do not perform this test satisfactorily enough!

leavemetogetonwithit wrote:then why do I need to employ something rather more sophisticated on the supply?

Oh Mike, you don’t have to that all if you do not wish, it’s not obligitory. But a Martingdale type mains continuity tester will suffice as a quick and effective means of testing the appliance’s supply line if you wish. They are cheap to buy and very effective.

leavemetogetonwith it wrote:Having only used a small current to test the appliance earth, I don’t know for sure that it would carry a large fault current without breaking down, do I?

You certainly don’t that’s true, not without a Loop tester anyway.:)

[leavemetogetonwithit]

Re: meggers

Martin wrote:I explain in my Megger Test.pdf the purpose of an insulation tester and it’s relationship between a low voltage earth check and a high voltage earth resistance check on the appliance. Digital multimeters do not perform this test satisfactorily enough!

leavemetogetonwith it wrote:
Having only used a small current to test the appliance earth, I don’t know for sure that it would carry a large fault current without breaking down, do I?

You certainly don’t that’s true, not without a Loop tester anyway.:)
Re 1st point in bold: You show a photo in your PDF of a bloke wearing a watch with a metal strap using a DMM to test earth continuity at 9 volts. (I checked before I wrote my original post.)

Re 2nd point, are you saying that you do use your loop tester to test the earth continuity from plug to appliance casing?

PS: I’m not trying to get at you (except with the bit about the watch strap 😆 ), I’m trying to get at the truth! 🙂
Mike.

[Martin]

Re: meggers

leavemetogetonwithit wrote:Re 1st point in bold: You show a photo in your PDF of a bloke wearing a watch with a metal strap using a DMM to test earth continuity at 9 volts. (I checked before I wrote my original post.)

Let me embolden the the part in that sentence you may have missed here Mike: –

I explain in my Megger Test.pdf the purpose of an insulation tester and it’s relationship between a low voltage earth check and a high voltage earth resistance check on the appliance. Digital multimeters do not perform this test satisfactorily enough!

leavemetogetonwithit wrote:Re 2nd point, are you saying that you do use your loop tester to test the earth continuity from plug to appliance casing?

No!

leavemetogetonwithit wrote:PS: I’m not trying to get at you (except with the bit about the watch strap 😆 )

It’s an ellesse watch my wife bought me recently. I don’t wear it at work and only put it on for special occasions such as this. 8) 😀

[Brains]

Re: meggers

Quote ”Oh Mike, you don’t have to that all if you do not wish, it’s not obligitory. But a Martingdale type mains continuity tester will suffice as a quick and effective means of testing the appliance’s supply line if you wish. They are cheap to buy and very effective”. Unquote.

Martin & Mike

Without wishing to get in the middle of your discussion, please, please be careful when using Martindale type plug-in testers. The neons will light at a very low voltage level. Great for a sanity check. Useless for checking reversed neutral-earth connections. Useless for confirming a good earth.

Please don’t take this the wrong way – but just a small reminder of why an EFLI tester should be used. Keep in mind that by measuring EFLI, you are confirming that the impedance is low enough for the circuit-protective- device (CPD) to trip within a specified period of time under fault. Keep in mind that high EFLI values may cause CPDs not to trip or take a long time to trip.

Most good EFLI Testers will indicate reversed/ incorrect polarity. Some will indicated high protective-earth voltages and abort the EFLI test.

Hope this helps.

Regards

[leavemetogetonwithit]

Re: meggers

Thanks for your input Brains. I wonder if you can see what I’m getting at because Martin doesn’t seem to be able to see it.
I’ll try and put it simply as possible because either I’m missing something or the rest of the world has got a blind spot where safety testing is concerned.
Following the advice in Martin’s PDF which I’m sure is accepted and acceptable practice:
1. Test earth continuity within appliance with a multimeter. That’s at 9 volts, mark you.

2. Test insulation resistance at 500v.

3. Test earth loop impedance at socket with meter which measures earth effectiveness at some 20 amps using the household’s own supply.

What I don’t understand is this. We are not testing the appliance’s own earth path at 240v / 20 amps so what’s the point of testing the supply earth at that level? If the earth path in the appliance were to be insufficiently robust to not break down at 240v / 20 amps or less the fact of the supply earth being good enough would be irrelevant.
OK, it’s a very unlikely scenario but isn’t that what testing should be covering?
Mike.

[Brains]

Re: meggers

Mike

Answering & responding to each point in turn:

1. Test earth continuity within appliance with a multimeter. That’s at 9 volts, mark you.

This gives an indication but will not pick up broken or strained conductors – thats why an Appliance Tester uses high current (nominally 20A).

2. Test insulation resistance at 500v.

Yep. thats okay. Although there is a move to measure earth leakage current as an alternative means of assessing insulation resistance (another subject for another day).

3. Test earth loop impedance at socket with meter which measures earth effectiveness at some 20 amps using the household’s own supply.

What I don’t understand is this. We are not testing the appliance’s own earth path at 240v / 20 amps so what’s the point of testing the supply earth at that level? If the earth path in the appliance were to be insufficiently robust to not break down at 240v / 20 amps or less the fact of the supply earth being good enough would be irrelevant.

The normal method of EFLI testing employed by a loop tester is to compare unloaded loop circuit voltage with the circuit voltage when loaded with a low resistance typically 10-20 ohms. This is where the 20A comes in.

Keep in mind what I said before. Care must be taken when carrying out EFLI testing. This method of test can create a shock hazard if the line-earth loop impedance is high & the test duration is not limited by the test instrument. In theses circumstances the potential of the the protectective (earth) conductor could approach line voltage for the duration of the test (hence my comment about testers indicating high PE voltages). Also stresses the need for Main Bonding Conductors within the installation.

OK, it’s a very unlikely scenario but isn’t that what testing should be covering?
Mike.

I hope I have helped your understanding with this. Please let me know if I need to provide some more information.

Regards

[leavemetogetonwithit]

Re: meggers

Brains wrote:

1. Test earth continuity within appliance with a multimeter. That’s at 9 volts, mark you.

This gives an indication but will not pick up broken or strained conductors – thats why an Appliance Tester uses high current (nominally 20A).

Regards
Ah!!! At last! So testing earth continuity within the appliance with a simple multimeter is not good enough!
Please please somebody now tell me what meter we need to use to do this part properly. Is it an EFLI tester with some special attachment or must we each buy a PAT tester?
Mike.

[BobHope]

Re: meggers

hi mike

been watching this for weeks but not stepped in untill now,

multimeter : general fault finding
megger/ insulation tester general fault finding
loop tester a must for testing customers house earth integrity
pat tester is the only instument that will test the earth integrity of an appliance.

Bob.

[adv]

Re: meggers

god wish i hadnt asked lol some size o thread 😳 candy dishwasher at scrap yard now 😆

[Brains]

Re: meggers

Some loop testers do have an ‘accessory’ lead for testing appliance earthing. However, I would suggest for washing machines, tumble dryers etc (e.g anything withing a plug) use an appliance tester.

For a high current appliance such as a cooker, the use of a loop tester with an ‘accessory’ lead is not a bad idea.

Remember that you can verify loop Z at the cooker terminals. However, please work safe when undertaking live testing.

Regards

[BobHope]

Re: meggers

thank you Brains,

but please keep this simple as you know there are lot of variable but the correct tool does the job.

Bob

[leavemetogetonwithit]

Re: meggers

Fantastic. Thanks Brains and Bob for clear and final answers to my confusion. That is much appreciated. At last I know what I should be aiming at.
I can see now that I’m gonna’ have to think seriously about getting a new pannier rack for the front of my bike to carry the two extra tools that I don’t currently (no pun intended) have, i.e. loop tester and PAT tester. Maybe I will get a bike trailer a bit like one of them wheeled suitcases that I can just unhook and wheel to the door.

Sorry adv about the dishwasher but I think that by asking that simple question you have benefitted our industry greatly.

Now wouldn’t it be brilliant if someone would come up with a way to make a meter that would perform ALL these testing tasks so we could breeze in and get the job done without tripping over all the various leads trailing about before we even get started on changing that door seal.
Or maybe somebody already has?
Mike.

[Author]

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