Using a proving unit.

[Rampage]

When isolating can't you just prove that your voltage indicator is working by connecting it to the supply terminals at the CCU, rather than buying a proving unit that's going to get left at someones house?

 

[Guest123]

Nothing wrong with proving your meter on a 'known source'.

 

[BlueToBits]

I think the idea is that you never have to test on or open up something 'live' , but I must admit, I do - not that I recommend it.

 

[Rampage]

I suppose you could use a mains inverter from your car?!
I'm trying to justify not buying one as I know its something that will get lost! With the exception of the Martindale I think they are all dark coloured!

 

[Rockingit]

I don't know anyone that actually owns a proving unit - as Lenny says, it's simply a 'known source' just to verify that your tester hasn't died in doing the test. I've always demonstrated safe isolation proceedures to my NICEIC inspector using the CU main terminals or whatever, and they are fine with that.

 

[Mr.Si]

Known Source is all that is asked for IIRC, so that sounds fine and was what I was taught as an acceptable way of doing things.

My Proving Unit is one of those Martindale ones, but my Fluke T120 doesn't fit in the holes! The terminals are too deep!

However, I may adjust the device or just buy a decent one...

 

[wallyanker]

I have a Kewtech KEW 1700 voltage indicator and according to the instruction manual it has a built in self test by holding the probes togther, it flashes all LEDs every seconds.

I assume this is an acceptable way of proving my unit??

 

[SirKit Breaker]

Self testing kit is acceptable, so is a known source. But if you are undergoing any sort of training then a proving unit is a must. I also do not use a proving unit except when i am teaching. I suppose i should practice what i preach, but it is not always practical, and i have the experience to know when i expect it to be dead or alive. I even make them dead test and lock off on my 3 phase test rig when it is physically unplugged from the socket. They need the practice.

Cheers........Howard

 

[topquark]

I have a proving unit, the only time it gets used is when there is actually a suppliers isolator for the incoming supply and the whole CU is being isolated.

 

[vaughant]

I've got a bright yellow one from Rs components but I've used it once.
The head of department is having a real purge on these right now,he's even drummed it into the apprentices that they must use a voltage indicator and this proving block rubbish to prove dead as it states in the regs you can't use a multimeter to test for voltage as it has multiple settings and you could be testing on the wrong setting.
My opinion is if you can't work out how to set a multimeter to volts ac/dc then you shouldn't be working with electricity.
The ridiculous thing is it states 240dc on the back but when you put your meter on it it shows 24v dc.
What a waste of time.
We were always taught known source and I'm still here 20 years on alive so I'm doing something right.

 

[gottahugenoggin]

technically speaking the proving unit is meant to be used before and after the circuit/fitting is isolated.With safe isolation and all that it would seem a little impractical on an upstairs light fitting/socket to use the CU as a known source if you have to run back downstairs to recheck the voltage indicator.I picked up a martindale off ebay for £30 all in

 

[Geordie Spark]

I don't know anyone that actually owns a proving unit - as Lenny says, it's simply a 'known source' just to verify that your tester hasn't died in doing the test. I've always demonstrated safe isolation proceedures to my NICEIC inspector using the CU main terminals or whatever, and they are fine with that.

You do now Bonny Lad !!! :smug2:

I've never used it though :sad_smile:

 

[MarkieSparkie]

The purpose of the Safe Isolation procedure is to ensure that a circuit is in a proven de-energised state that is safe to work on, and therefore complying with the statutory requirements of EAWR:1989, Regulation 14a. Which states "No person shall be engaged in any work activity on or near any live conductor (other than one suitably covered with insulating material so as to prevent danger) that danger may arise unless - a) it is unreasonable in all circumstances for it to be dead; and b) it is reasonable in all the circumstances for him to be at work on or near it while it is live; and c) suitable precautions (including where necessary the provision of suitable protective equipment) are taken to prevent injury. Such work is permitted only if conditions a) and b) and c) are satisfied, ‘Work’ is not confined to electrical work but includes any work activity.”
HSE, Guidance Note GS38, conveniently paraphrases the salient points of EAWR:1989, Regulation 14a, “No live working unless:- (i) it is unreasonable to work dead; AND (ii) it is reasonable to work live; AND (iii) suitable precautions are taken to prevent injury.
It is my view that if the Safe Isolation procedure is implemented to prove a circuit is “dead”, the electrician has decided and implied that it is unreasonable to work live. If he then checks the operation of his approved voltage tester (AVT) on a known LIVE supply, he is effectively infringing the very regulation he is attempting to comply with.
So, therefore, I believe a proving unit (providing it can test the AVT to full scale) to be the best method of checking the operation of the approved voltage tester, allowing the electrician to satisfy the requirements EAWR:1989, Regulation 14a, without conflict.

 

[vaughant]

Typical regs contradictions!!!!
I suppose it makes sense to test on a proving unit but again,how far do we go?how do we know the proving units giving out the right voltage?should we test that first and what do we test that on?
Gets a bit silly in the end don't you think?

 

[fuzzydunlop]

So, therefore, I believe a proving unit (providing it can test the AVT to full scale) to be the best method of checking the operation of the approved voltage tester, allowing the electrician to satisfy the requirements EAWR:1989, Regulation 14a, without conflict.

Being really pedantic, it says nothing of the sort