Proving dead at the CU

[ringer]

Can you use main incoming L&N as known voltage source instead of a proving unit?

 

[IQ Electrical]

Yes, I do it on every annual assessment and you're confirming supply polarity at the same time.

 

[ian.settle1]

Can you use main incoming L&N as known voltage source instead of a proving unit?

I wouldn't as what if your test lamp said it was dead and it wasn't because you have a duff test lamp?

 

[IQ Electrical]

I wouldn't as what if your test lamp said it was dead and it wasn't because you have a duff test lamp?

How is that scenario improved using a proving unit?

 

[Amp David]

Think if you tested on the incomming side of the main switch and you had no voltage, then surely you'd realise your test was dead anyway or theres a power cut in the areaLOL

 

[Adam W]

If the lamp fails to light on the outgoing side of the main switch you should then prove the tester, ie it should light on the incoming side (or in a proving unit).
If it doesn't, either your test lamp is broken, or as already metioned, there's a power cut.

 

[Des 56]

Can you use main incoming L&N as known voltage source instead of a proving unit?

Never seen a proving unit and certainly never owned one

There is no better way of first proving your meter actually works than by shoving it onto the national grid
Then theres no better way of deciding a circuit is live or dead, than by using that same meter to give you many more days of sparking without burning those pinkies

 

[Deleted member 19807]

I have done this on every assesment i have had and its always been ok, and i have a proving unit for when not at tha cu.

 

[Jimmy Boy]

A proving unit lights up if working. I guess if you wanted to Mr health and safety you could argue using the incoming main to do an initial proving could be classed as 'Live working' and classed as unnecessary as other means available, and secondary testing for voltage is necessary to prove isolation..Food for thought

 

[Deleted member 19807]

if you are doing the ze test you have no choice then to work live so you might as well do the proving at the cu when testing for a dead cu to perform r1r2 tests ect.

edit my proving unit don't light up, my voltage tester dose.

 

[IQ Electrical]

if you are doing the ze test you have no choice then to work live so you might as well do the proving at the cu when testing for a dead cu to perform r1r2 tests ect.

edit my proving unit don't light up, my voltage tester dose.

My proving unit has no 'lights' either!

 

[thewetspark]

I have a proving unit but mostly use whatever is available and close, the idea is to "prove" your tester is working, if it doesn't come on when you expect it to then you have to get something else to test that supply with, even if that supply is your proving unit. Meter tails are great but if my Martindale said they were dead I'd still check them out again with something else before I got hold of them. It's about safety so you have to "prove" your tester before and after you test something is dead. The book says with a "known" supply, you only "know" its a supply if the tester comes on.

 

[Jimmy Boy]

My Marty lights up

 

[Deleted member 19807]

no, you know its dead because you prove your tester not the supply. thats what a proving unit dose

 

[ringer]

So if you're up for assessment, and you're working on a CU, and you have to hand a readily available 'known source'. But if you don't own a proving unit, is the assessor going to say 'what happens when you're not at the CU, how will you prove dead if you don't own a proving unit?'?

 

[Jimmy Boy]

If you have a Proving unit and it isn't working/calibrated you shouldn't be doing an on site assessment period

 

[Deleted member 19807]

my proving unit dose not require calibration, it just gives out voltage when i stick my voltage tester probes in it to prove my voltage tester is working.

 

[Jimmy Boy]

Mate all testing equipment needs to be calibrated, and proved with a certificate.

 

[IQ Electrical]

Mate all testing equipment needs to be calibrated, and proved with a certificate.

In my many years in this business I have never calibrated or been asked to calibrate a proving unit, nor can I find any requirements to calibrate!

Of course the calibration companies will provide this service if asked, in return for £40 or £50 but then again, they'd probably calibrate a Thermos Flask if you requested it.

 

[eskimo39]

You do not require a proving unit if you follow the safe isolation procedure.

After identifying circuit to work on you test your tester on a known supply (This can be the incomming tails before isolation, a proving unit or a different circuit). If all LED's light up you know it is working so you then test the supply you have isolated.

If correctly isolated, no LED's will light up!!!

Then re-test you tester on known supply (to check all LED's are still working and it hasn't died between proving and checking isolation) if all LED's light up, then you know the isolated supply is dead.

This might be usefull here : http://www.esc.org.uk/pdfs/business-and-community/electrical-industry/BPG2_09.pdf

Check out page 13

Cheers guys

 

[Jimmy Boy]

In my many years in this business I have never calibrated or been asked to calibrate a proving unit, nor can I find any requirements to calibrate!

Of course the calibration companies will provide this service if asked, in return for £40 or £50 but then again, they'd probably calibrate a Thermos Flask if you requested it.

Well although no requirement to under BS 7671, 612.1 refers to requirements, and best practice and common sense would say you should...

http://www.esc.org.uk/pdfs/business-and-community/electrical-industry/BPG7_10.pdf

Also this clip from DIS registration from NICEIC...

A check of test instruments and leads used for
certification purposes. As a minimum, the business
needs to have access to instruments to provide
voltage indication and to test insulation resistance,
continuity, phase/earth loop impedance and residual
current devices. You should have records to
demonstrate that a system is in place to ensure the
accuracy and consistency of test instruments used
for certification purposes. These will need to be
available for inspection. An example leaflet is enclosed
with this pack.

http://niceic.com/Uploads/File2368.pdf

 

[IQ Electrical]

I have a copy of that form but it doesn't call for monthly or any other such checks on a proving unit does it?

 

[Jimmy Boy]

IQ I misread you OP I thought you said no test equipment needed calibration I apologise.

100 Lines...

must read slower
must read slower
ATB Steve

 

[IQ Electrical]

IQ I misread you OP I thought you said no test equipment needed calibration I apologise.

100 Lines...

must read slower
must read slower
ATB Steve

I thought it was weird that you were persisting with it!

 

[Jimmy Boy]

I should learn my lesson and not read forum posts on a day off prior to drinking copious amounts of Wife Beater.........lmfao

 

[roukel01]

never owned a proving unit, and never had to show safe isolation at any assesment. Flick the main switch off and the lights go out! usually enough proof for me to start work on a domestic CU.

 

[Des 56]

never owned a proving unit, and never had to show safe isolation at any assesment. Flick the main switch off and the lights go out! usually enough proof for me to start work on a domestic CU.

Thats sure to make the health and safety brigade squirm
The knuckle wrapping will soon begin

 

[roukel01]

Thats sure to make the health and safety brigade squirm
The knuckle wrapping will soon begin

Thought you'd like that one!!!

 

[Jimmy Boy]

your knicked my old son

 

[ian.settle1]

Thats sure to make the health and safety brigade squirm
The knuckle wrapping will soon begin

Squrim squirm now where is that cane?

 

[Goody]

So if you're up for assessment, and you're working on a CU, and you have to hand a readily available 'known source'. But if you don't own a proving unit, is the assessor going to say 'what happens when you're not at the CU, how will you prove dead if you don't own a proving unit?'?

I have a Fluke T120 Voltage/Continuity Tester and my proving unit is a couple of 9 volt batteries in a plastic box with terminals attached to two bolts (screws) showing out (yes, you got the idea) - a cheap & cheerful proving unit.

Works wonders every time!