Earth loop without neutral

[Jimmy Boy]

I think you need to read slower..

I didn't say use 500ma fused leads I said the opposite I said they wouldn't be suitable for a loop test.

I attach a PDF from HSE on GS38 read page 6 Design,safety requirements..Then tell us all what it says on fuse size.

http://www.hse.gov.uk/pubns/priced/gs38.pdf

 

[WayneL]

........ read page 6 Design,safety requirements..Then tell us all what it says on fuse size.

You'll notice that Page 6 covers Section 9............

9 The test probes and leads used in conjunction with a voltmeter, multimeter, electrician’s test lamp or voltage indicator should be selected to prevent danger. Good test probes and leads will have the following:

.......suitable high breaking capacity (hbc), sometimes known as hrc, fuse, or fuses, with a low current rating (usually not exceeding 500 mA), or a current-limiting resistor and a fuse

But we're not using any of them, are we Steve.............we're not testing for voltage.

Testing for voltage, we would want very little current to be flowing.

But we're performing 'Loop Tests'......20A loop tests!

So we want Page 8.........Section 14/15

14 The use of test equipment by electricians falls into three main categories:
(a) testing for voltage (voltage detection);
(b) measuring voltages; and
(c) measuring current, resistance and (occasionally) inductance and capacitance.
Item (a) forms an essential part of the procedure for proving a system dead before starting work but may also be associated with simple tests to prove the presence of voltage. Items (b) and (c) are more concerned with commissioning procedures and fault finding.

[FONT=Helvetica 55 Roman,Helvetica 55 Roman][FONT=Helvetica 55 Roman,Helvetica 55 Roman]Precautions before testing[/FONT]
[/FONT]
15 Before testing begins it is essential to establish that the test device including all leads, probes and connectors is suitably rated for the voltages and currents which may be present on the system under test.

I think someone else needs to read slower

 

[Graeme Harrold]

Thats why I like my Fluke, the fuses are in the tips, not the box

 

[Jimmy Boy]

I know ! I said that in my OP go back and read it..slowly

 

[WayneL]

I know ! I said that in my OP go back and read it..slowly

So you agree that test leads can be GS 38 compliant, regardless of the size fuse that is protecting them - as long as they are 'suitably rated for the voltages and currents which may be present'


Graeme, we are talking about fuses in the 'tips (probes)' - what size fuses are in your 'Fluke' leads. (for loop testing)

 

[Jimmy Boy]

You seem to do that a lot try and keep up old chap.

To be truly GS38 compliant the leads must be fused to the appropriate rating for the test being carried out, normally this would be 500ma, this clearly would not be sufficient for a loop/pfc test so you would need to fuse the leads at a rating appropriate to the test, phone up Meggar tech and ask them why their leads they supply are not GS38 compliant ? The answer will be the tester has a HBC fuse in it, but it ain't 500ma !

I agree with the content of my post which I can understand but clearly for reasons I can't explain you can't. nuff said now my teeth itch

 

[WayneL]

I agree with the content of my post which I can understand but clearly for reasons I can't explain you can't. nuff said now my teeth itch

I do understand your post, Steve, and you are spot on - BUT.....

I'ts your second sentence - 'normally this would be 500mA' that I have the problem with - the fuse has to be rated for the testing that you are doing e.g. EFLI or PFC.

You were implying through this, and your other posts, that leads that don't have 500mA fuses in the probes are not GS38 compliant - but they are - your bold, underlined sentence says it all.

 

[Jimmy Boy]

And the 1553 has a 500mA (F) 10kA 500V fuse in it

 

[WayneL]

And the 1553 has a 500mA (F) 10kA 500V fuse in it

Agreed, but you try the leads with those fuses in to loop test and you'll blow them every time.

 

[Jimmy Boy]

OK I admit the school boy error Wayne my terminology was slightly misleading This is for you matey..

 

[WayneL]

Hey, I love these discussions - if nothing else, it keeps you thinking about things and not getting complacent.

And I must admit, I learn something most days on here.

 

[Jimmy Boy]

Yea agreed Wayne it does keep you on the ball, I have really upped my knowledge since joining this forum, at times it's trying but very rewarding, did we get a final resolution on the Max Zs to be entered on the 7671 forms for circuits protected by RCD/RCBO's ? Is it the 1667 in table 41.5 or the values in table 41.3 ?
ATB Steve

 

[WayneL]

Yea agreed Wayne it does keep you on the ball, I have really upped my knowledge since joining this forum, at times it's trying but very rewarding, did we get a final resolution on the Max Zs to be entered on the 7671 forms for circuits protected by RCD/RCBO's ? Is it the 1667 in table 41.5 or the values in table 41.3 ?
ATB Steve

I wasn't part of that discussion, mate.

For what it's worth, I think that the figure that you enter there should be related to the device that you are (in your mind), using for 'earth fault protection'.

In other words, if you are installing an RCD for 'Additional Protection' and the MCB is, in theory, your actual earth fault protection, then I think it should be values from 41.3.

If you are actually fitting an RCD as 'earth fault protection' - i.e. you can't get your Zs low enough for whatever reason - then I think you'd have to enter values from 41.5

I know the RCD will trip first in either scenario, but it just makes sense to me........but it is only my opinion.
I think most sparks enter 1667 for RCD protected circuits.

 

[Graeme Harrold]

So you agree that test leads can be GS 38 compliant, regardless of the size fuse that is protecting them - as long as they are 'suitably rated for the voltages and currents which may be present'


Graeme, we are talking about fuses in the 'tips (probes)' - what size fuses are in your 'Fluke' leads. (for loop testing)

Couldnt be bothered going out last night to check, but the internal fuse in the Fluke is 1A 500V 50KA FAST, this is for general protection of the unit. The lead fuses are rated at 10A 600V. As for the Loop test specs on the Fluke at 230V, it sends 12A out for 10ms, 20A only goes out for 10ms when testing 400V. As for the