On Wednesday, August 7, 2013 2:39:24 PM UTC+1, Archibald wrote:
Portable appliances aren't really something a DIY type would normally
test BTW, You'r surely not suggesting someone tucks a PAT tester
amongst the groceries next time they get a kettle from Asda?

A new kettle shouldn't need testing, or even inspection.

However a lot of people have some older appliances (some people even collect them) and extension leads etc.

Anyway, even a new Megger is cheaper than what the kink shops charge for electro-stim equipment ;-)

On Wed, 7 Aug 2013 22:03:48 +0100, tony sayer
wrote:

Not sure what kind of fuse you have in mind. Most cheap meters will have
a 20mm glass cartridge fuse, inline with the current measurement ranges
(although often not the highest range). They may not even have any fuse
inline when used on other ranges.

Probably as effective as the semiconductor rated devices fitted to the
Flukes & similar. Personally I wouln't bother too much about fuses
anyway. As you state, the higher current shunts are not fused and at
the lower end of the ranges, the components often beat the fuse hands
down on the route to destruction.


Hence these meters are not suitable for making measurements on high
energy locations (e.g. inside a consumer unit)

Bilge! I use a Wickes device, glass fuse, not sure what current
because it came out of my bits box last time I tried to check a 110V
supply when tweaking a current loop. It has actually lasted aroud five
years which is a miracle considering it gets soaked in water, acid,
caustic and all the rest of the gunge that ends up in the water
treatment system.

I use it for personal domestic wiring and industrial three phase 415V
supplies. I could splash out a fortune on test gear, but I know it's
going to have a short life whatever its price tag, so I just go for
something that is around 1kv max DC & AC, resolves down to a
microVolt/ microAmp and will do DC & AC Amps. Most meters have an
adequate Ohms range, so that's it.

Whatever meter I have bought, I never did bother trying to find out if
it was even fused before purchase, there isn't too much point.


So your working on those sorts of systems and are that tight to buy a
half decent pro meter?. You can get good Fluke meters on e-bay for
around 40 to 50 quid sometimes. I managed to get one from a S/H test
equipment supplier c/w decent rated leads and fuses etc for that sort of
money...

Buggered if I'd use a cheap chinkie one of dubious origin;!...

Buggered if I would use second hand rubbish. I would not feel too
happy if my gear didn't come out of a box.

Anyway i'm just being practical. The spec on a Wickes meter is more
than adequate for my work. I could destroy it, or a Fluke for that
matter in an instant. Whats wrong with the cable on a Wickes meter
incidentally? What was wrong with the insulation on a two for four
quid Maplin DMM by the way. What is so critical about the rating of
the cables and what do I look for when buying same?

The last Fluke I bought was totally useless BTW. I assumed a DMM
costing £70-00 or thereabouts would have a current range... Wrong!

Just what as a "pro" meter incidentally. Apart from the price how
would you define a meter as being suitable for a professional?

Personally I would deem any meter suitable for a professional if he
knew when and how to use it, and got paid for using it. full stop!

On a final point, within reason I can have any meter I wish, but if
its not over £100-00 or so I can just call into a trade counter or
suchlike.

I think my Wickes meter was £19-00 or so, it does the job as well as a
Fluke would. I didn't have to order the thing and wait for delivery
and the fact that it does not get looked after, gets dropped, soaked
and generally mistreated means that it has outlived my expectations by
at least four years.

One other downside of an expensive meter incidentally is having to
order a replacement less than a month after unboxing the last one.
It has happened!!

AB

In article ,
Archibald wrote:
I think my Wickes meter was £19-00 or so, it does the job as well as a
Fluke would. I didn't have to order the thing and wait for delivery
and the fact that it does not get looked after, gets dropped, soaked
and generally mistreated means that it has outlived my expectations by
at least four years.

One other downside of an expensive meter incidentally is having to
order a replacement less than a month after unboxing the last one.
It has happened!!

My Fluke is a delight to hold and use - quite unlike any other. Only sort
of matters if you appreciate such things. I do.

--
*No I haven't stolen it , I'm just a **** driver*

Dave Plowman London SW
To e-mail, change noise into sound.

On Thu, 08 Aug 2013 00:29:52 +0100, "Dave Plowman (News)"
wrote:

In article ,
Archibald wrote:
I think my Wickes meter was £19-00 or so, it does the job as well as a
Fluke would. I didn't have to order the thing and wait for delivery
and the fact that it does not get looked after, gets dropped, soaked
and generally mistreated means that it has outlived my expectations by
at least four years.

One other downside of an expensive meter incidentally is having to
order a replacement less than a month after unboxing the last one.
It has happened!!

My Fluke is a delight to hold and use - quite unlike any other. Only sort
of matters if you appreciate such things. I do.

:--)

It's whatever grabs yer! I have actually had a few Flukes, they are
much like any other meter from a practical point of view. I would say
their main advantage is the protection fuse though. It can be damned
difficult wrapping a strand of wire round a 20mm fuse after measuring
Volts on the mA range. The Fluke wins hands down on that score, the
protection fuse is so big, it's a doddle to bypass it!

When I was a young apprentice, before we properly studied "Ohms per
Volt" I bought an Avo 7. The meter lasted around two years before I
pulled it to bits trying to cure an intermittent Ohms range. The Avo 7
was classed as totally unsuitable for my line of work, not only did I
use it, but found it's characteristics very useful for biasing on
transistors and suchlike. The meter served me almost as well as the
Avo 8 that came later.

It isn't what youve got, it's what you do with it!


AB

In article ,
wrote:
On Wednesday, August 7, 2013 2:39:24 PM UTC+1, Archibald wrote:
Portable appliances aren't really something a DIY type would normally
test BTW, You'r surely not suggesting someone tucks a PAT tester
amongst the groceries next time they get a kettle from Asda?

A new kettle shouldn't need testing, or even inspection.

indeed not, but I did buy 4 theatre lights from CPC and found that on one
the earth lead was insulated from the metal body by a layer of paint.


However a lot of people have some older appliances (some people even
collect them) and extension leads etc.

yes - often with the plug top no longer gripping the cable sheath.

Anyway, even a new Megger is cheaper than what the kink shops charge for
electro-stim equipment ;-)

--
From KT24

Using a RISC OS computer running v5.18

So your working on those sorts of systems and are that tight to buy a
half decent pro meter?. You can get good Fluke meters on e-bay for
around 40 to 50 quid sometimes. I managed to get one from a S/H test
equipment supplier c/w decent rated leads and fuses etc for that sort of
money...

Buggered if I'd use a cheap chinkie one of dubious origin;!...

Buggered if I would use second hand rubbish. I would not feel too
happy if my gear didn't come out of a box.

Oh dear!, that shows your lack of knowledge of good test equipment. Most
all of that is built very well indeed and has a very long service life.
There is a healthy market in used equipment ands it gets there for all
manner of reasons.


Anyway i'm just being practical. The spec on a Wickes meter is more
than adequate for my work. I could destroy it, or a Fluke for that
matter in an instant. Whats wrong with the cable on a Wickes meter
incidentally? What was wrong with the insulation on a two for four
quid Maplin DMM by the way. What is so critical about the rating of
the cables and what do I look for when buying same?

Well we need a meter for field use that can handle measurement of very
small currents and voltages and at the same time can check the incoming
mains supplies which are very "stiff" and I wouldn't like to trust a 10
quid or otherwise device across that sort of power!. Its quite easy to
forget to take the leads of the amps measurement range when your
checking three phase supplies;!.



The last Fluke I bought was totally useless BTW. I assumed a DMM
costing £70-00 or thereabouts would have a current range... Wrong!


So it didn't measure current at all, which model was that then?..


Just what as a "pro" meter incidentally. Apart from the price how
would you define a meter as being suitable for a professional?

One that can be calibrated for a start. One that has a good build
quality and one that can cope with accidental connection to rather more
powerful supplies then what you might in a transistor radio for a
start..

Personally I would deem any meter suitable for a professional if he
knew when and how to use it, and got paid for using it. full stop!


I suppose then your version of "professional" differs from mine...

On a final point, within reason I can have any meter I wish, but if
its not over £100-00 or so I can just call into a trade counter or
suchlike.

I think my Wickes meter was £19-00 or so, it does the job as well as a
Fluke would. I didn't have to order the thing and wait for delivery
and the fact that it does not get looked after, gets dropped, soaked
and generally mistreated means that it has outlived my expectations by
at least four years.

One other downside of an expensive meter incidentally is having to
order a replacement less than a month after unboxing the last one.
It has happened!!

Why?..


AB


--
Tony Sayer

In article , Archibald
scribeth thus
On Thu, 08 Aug 2013 00:29:52 +0100, "Dave Plowman (News)"
wrote:

In article ,
Archibald wrote:
I think my Wickes meter was £19-00 or so, it does the job as well as a
Fluke would. I didn't have to order the thing and wait for delivery
and the fact that it does not get looked after, gets dropped, soaked
and generally mistreated means that it has outlived my expectations by
at least four years.

One other downside of an expensive meter incidentally is having to
order a replacement less than a month after unboxing the last one.
It has happened!!

My Fluke is a delight to hold and use - quite unlike any other. Only sort
of matters if you appreciate such things. I do.

:--)

It's whatever grabs yer! I have actually had a few Flukes, they are
much like any other meter from a practical point of view. I would say
their main advantage is the protection fuse though. It can be damned
difficult wrapping a strand of wire round a 20mm fuse after measuring
Volts on the mA range. The Fluke wins hands down on that score, the
protection fuse is so big, it's a doddle to bypass it!

Well least we know where we stand on this..

You can work here;







I'll go over there -: )


When I was a young apprentice, before we properly studied "Ohms per
Volt" I bought an Avo 7. The meter lasted around two years before I
pulled it to bits trying to cure an intermittent Ohms range. The Avo 7
was classed as totally unsuitable for my line of work, not only did I
use it, but found it's characteristics very useful for biasing on
transistors and suchlike. The meter served me almost as well as the
Avo 8 that came later.

It isn't what youve got, it's what you do with it!

Yes .. nuff said I reckon...


AB

--
Tony Sayer

On Thu, 8 Aug 2013 11:40:02 +0100, tony sayer wrote:

Its quite easy to
forget to take the leads of the amps measurement range when your
checking three phase supplies;!.

Saw a line of DMMs that had a simple mechanical device, a disc attached to the
range knob, that blocks off the amps and volts lead holes, depending. You either
can't stick the leads in on the wrong setting, or the plugged leads block
turning the knob to an unsuitable position. One still can set it amps and probe
for volts, but not hook up to volts and then set to amps...

Simple and useful idea, wish I'd thought of it.

Thomas Prufer

On 07/08/2013 21:38, Archibald wrote:
On Wed, 07 Aug 2013 17:42:13 +0100, John Rumm
wrote:

On 07/08/2013 11:37, Archibald wrote:
On Mon, 05 Aug 2013 12:56:12 +0100, John Rumm

[1] This is one of those occasions (where you may be routinely making
connections to live circuits) where you *must* get something that is
properly designed to do the job safely - that means decent input
protection, arc protection, and a HRC fuse and not a piddly little 20mm
glass one. There is some cheap kit on ebay, but I would be wary until
you have seen exactly how its constructed.

I think you'll find that those fuses are actually semiconductor rated
devices. Designed to protect the electronics.

No, you don't need HRC fuses and blast protection chambers to protect
electronics!

It's an easy trap for
the unwary to fall into though as they do look like a bog standard
ceramic in some cases.

Not sure what kind of fuse you have in mind. Most cheap meters will have
a 20mm glass cartridge fuse, inline with the current measurement ranges
(although often not the highest range). They may not even have any fuse
inline when used on other ranges.

Probably as effective as the semiconductor rated devices fitted to the
Flukes & similar. Personally I wouln't bother too much about fuses

The fuses fitted to Flukes are HRC fuses capable of interrupting fault
currents of up to 10kA. (the reason they are so 'kin expensive!)

anyway. As you state, the higher current shunts are not fused and at
the lower end of the ranges, the components often beat the fuse hands
down on the route to destruction.

Hence these meters are not suitable for making measurements on high
energy locations (e.g. inside a consumer unit)

Bilge!

You are obviously failing to comprehend the issue here. Yes any cheap
meter will give you a measurement. It might be accurate enough, the
meter might even last for years. No one is disputing that. What we are
attempting to highlight is the way it responds when an event beyond your
control subjects it to catastrophic over volt, may not be to your liking.

I use a Wickes device, glass fuse, not sure what current

[snip]

Do as you like. However my advice would be to only use a proper Cat III
or IV rated meter, when carrying out tests on high energy sources. To do
otherwise is foolish IMO.

A DIY system is hardly going to be certified by the person dealing
with it, so I would suggest anyone having a solid idea of what they
are testing, could do the job with a cheap multimeter and a few
ancilliary bits & bobs. I would have serious doubts that any DIY
practicioner would "routinely" make test connections to live circuits
incidentally. so wear & tear shouldn't be a major factor to contend
with.

I think you are missing the point. While you can make many useful tests
with a multimeter, even a cheap one, there are a number of places where
you can't do so safely.

Also how do you carry out a full RCD test, or Insulation resistance test
with a MM? You could produce a PSSC result perhaps, but would also have
difficulty measuring the earth loop impedance.

I'm not sure what newsgroup you think you are on but this is uk.d-i-y.
No I do not think I would have difficulty measuring earth loop
impedance incidentally.

I have never completed an earth loop impedance test on any of my
wiring BTW even though we have dedicated testers for the installation
personnel,

Shrug

I would doubt that many DIY people have either.

You may doubt, but it it does not stop you being wrong.

Personally now for the most part I use a none contact device, and
although the thing, like any instrument "needs interpreting", it gives
a good indication and has saved me getting a meter out on many, many
occasions.

These are fine for go/no go indications, but they don't give you a
complete set of test capabilities.

Thank you, I feel most enlightened.

That's odd, you still appear clue resistant.

Whatever way it's dressed up, testing wiring is just an application
and understanding of Ohm's law. In my experience even some of the
cheapest junk on the market will provide measurements of more than
adequate accuracy.

Indeed, and usually you will live to tell the tale, but sometimes you wont.

It isn't the test equipment! none of it's perfect and it does not

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

Next time you probe a 3 phase supply, you may wish to reflect on this
comment from the above: "Once the bus bars began to arc, the victims'
fates were sealed, as there was no turning back at that point"

The purpose of the input protection is to protect you primarily and not
the meter. If you are taking a voltage reading close to your consumer
unit, and the meter experiences a 10kV transient, its better that it
dies in the process of blowing its fuse and popping a few MOVs, tham
allowing an arc flash to engulf the user.

Really?

Yes

Is this the same mains that all those TV's radios, table
lamps and such like are connected to?

No its not, and that is the key.

Making measurements inside a mains appliance (while that has its own
risks), does not usually expose you to a high energy source - you are
nicely buffered by a reasonable length of domestic wiring with a few
tenths of an ohm of loop impedance [1]. If things go pear shaped there
are likely to only be few hundred amps of fault current available.

Taking readings at a consumer unit may expose you to a source of many
thousands of amps of prospective short circuit currant.

Perhaps you should go on a
crusade to fit better fuses on all this equipment before the users are
engulfed in a searing hot plasma, or is there some magical barrier in
a consumenr unit that stops transients dead?

Given a working knowledge of ohms law, you should be able to work that
out for yourself.

Test equipment fuses are not semiconductor rated to protect the user!
I suppose people are "semiconductors", but they dont fit semiconductor
fuses to toasters do they? If they see fit to put the things in meters
and not toasters does it not suggest that they may not after all be
trying to protect the user?

Has it occurred to you, that the fusing in the meter may have more than
one purpose? (or for that matter, why some meters have more than one fuse?)


[1] Usually, although you might want to ask Adam what the PSCC is in his
house...

--
Cheers,

John.

/================================================== ===============\
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|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Wed, 7 Aug 2013 22:03:48 +0100, tony sayer wrote:

So your working on those sorts of systems and are that tight to buy a
half decent pro meter?.

It can't be in any professional capacity, or if it is H&S has clearly gone out
of the window.

You can get good Fluke meters on e-bay for
around 40 to 50 quid sometimes.

No need to even buy secondhand at the moment, Fluke 113 £84 quid NEW (that is
probably plus VAT)

http://www.fluke.com/fluke/uken/wher...i/65_years.htm

CATIV 300V, CATIII 600V

Buggered if I'd use a cheap chinkie one of dubious origin;!...

Absolutely, although quite a few Flukes, including this 113 are made in China
now.


--

On 7 Aug 2013 21:16:29 GMT, Bob Eager wrote:

On Wed, 07 Aug 2013 21:38:33 +0100, Archibald wrote:

Incidentally, years back I had an AVO eight, the industry standard hyper
priced instrument of my youth. I dont even think it was fused.

They have a fuse, and a cut-out.

Not 100% sure about a fuse as its so long since I've used one or had one apart
but definitely agree on the cutout.

There is no way they would be permitted to be used for field measurements on any
mains fed equipment in any establishment with even the slightest hint of a
safety culture.


--

On 08/08/2013 11:40, tony sayer wrote:

Just what as a "pro" meter incidentally. Apart from the price how
would you define a meter as being suitable for a professional?

One that can be calibrated for a start. One that has a good build
quality and one that can cope with accidental connection to rather more
powerful supplies then what you might in a transistor radio for a
start..

You can a fair bit from the Cat it claims to match - however I would
only believe it if its also certified by a proper testing authority. (I
have seen a number of cheap meters that claim CAT II or III for example,
but obviously come nowhere close when you look at the internals).


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, 8 August 2013 13:17:36 UTC+1, The Other Mike wrote:
On 7 Aug 2013 21:16:29 GMT, Bob Eager wrote:



On Wed, 07 Aug 2013 21:38:33 +0100, Archibald wrote:



Incidentally, years back I had an AVO eight, the industry standard hyper

priced instrument of my youth. I dont even think it was fused.

I have a few 8 mk II here even have a manual, no 15V batteries though.

AVOCET house 92-96 Vauxhall bridge road SW1 but in teh model 9 manual they moved to Dover


We called them smiley meters at school because when upside down the scale looked like a clowns mouth the the main knobs looked like eyes.




There is no way they would be permitted to be used for field measurements on any

mains fed equipment in any establishment with even the slightest hint of a

safety culture.

probabley not now, butn in the early 80s they were still in use here for measring mains voltages.


I just ordered sixty of these fopr our students.
http://www.rapidonline.com/Test-Meas...2-454d98674cba

But we don't go above 60V DC, and most of the time under 30V.
The above seem to be great little meters for the price and the use we & the students will put them to.

On Thu, 08 Aug 2013 13:17:36 +0100, The Other Mike wrote:

On 7 Aug 2013 21:16:29 GMT, Bob Eager wrote:

On Wed, 07 Aug 2013 21:38:33 +0100, Archibald wrote:

Incidentally, years back I had an AVO eight, the industry standard
hyper priced instrument of my youth. I dont even think it was fused.

They have a fuse, and a cut-out.

Not 100% sure about a fuse as its so long since I've used one or had one
apart but definitely agree on the cutout.

It's in the battery compartment - on all marks of the 8 as far as I know
(I have a Mark 1, a Mark 3 and a Mark 7 here).

There is no way they would be permitted to be used for field
measurements on any mains fed equipment in any establishment with even
the slightest hint of a safety culture.

Why not?

--
Use the BIG mirror service in the UK: http://www.mirrorservice.org
My posts (including this one) are my copyright and if @diy_forums on
Twitter wish to tweet them they can pay me £30 a post
*lightning surge protection* - a w_tom conductor

On 08/08/2013 11:40, tony sayer wrote:

Anyway i'm just being practical. The spec on a Wickes meter is more
than adequate for my work. I could destroy it, or a Fluke for that
matter in an instant. Whats wrong with the cable on a Wickes meter
incidentally? What was wrong with the insulation on a two for four
quid Maplin DMM by the way. What is so critical about the rating of
the cables and what do I look for when buying same?
Well we need a meter for field use that can handle measurement of very
small currents and voltages and at the same time can check the incoming
mains supplies which are very "stiff" and I wouldn't like to trust a 10
quid or otherwise device across that sort of power!. Its quite easy to
forget to take the leads of the amps measurement range when your
checking three phase supplies;!.

I expect this will be fine for most DIY use.

http://www.lidl.co.uk/cps/rde/SID-AF...l&id=4807&ar=3

next week.

John Rumm wrote:
On 07/08/2013 14:51, Dave Plowman (News) wrote:
In article ,
charles wrote:
I haven't the experience of the likes of Adam, but have yet to come
across a fault like this that a DVM doesn't show up. And yes, I do
have a high voltage insulation tester.

I have come across many, both in wiring, extension cables and fittings
(PATing).

Quite - but did you also do a test with an ordinary DVM to see if it too
showed the fault?

I used to have a lovely hand Megger running off 6x AA cells.
Unfortunately, a cell exploded inside and F***ed up the contacts.

What I'm looking for is an insulation etc fault that only shows up at
high
voltage.

I had one today in someone's kitchen - old socket on the end of a 2m
spur. L to E measurement on a MM read open circuit, and at 500V was
showing around 54 M ohms (still in spec - but poor enough to warrant
replacement shortly)


Meggers are useful in the right hands but I would not recommend casual
use in these days of solid state stuff.
Back in my day we could whack them on almost any wiring, these days you
would blow things up right left and centre.

On 08/08/2013 15:33, F Murtz wrote:
John Rumm wrote:
On 07/08/2013 14:51, Dave Plowman (News) wrote:
In article ,
charles wrote:
I haven't the experience of the likes of Adam, but have yet to come
across a fault like this that a DVM doesn't show up. And yes, I do
have a high voltage insulation tester.

I have come across many, both in wiring, extension cables and fittings
(PATing).

Quite - but did you also do a test with an ordinary DVM to see if it too
showed the fault?

I used to have a lovely hand Megger running off 6x AA cells.
Unfortunately, a cell exploded inside and F***ed up the contacts.

What I'm looking for is an insulation etc fault that only shows up at
high
voltage.

I had one today in someone's kitchen - old socket on the end of a 2m
spur. L to E measurement on a MM read open circuit, and at 500V was
showing around 54 M ohms (still in spec - but poor enough to warrant
replacement shortly)


Meggers are useful in the right hands but I would not recommend casual
use in these days of solid state stuff.
Back in my day we could whack them on almost any wiring, these days you
would blow things up right left and centre.

Yup, great for testing new wiring before connecting to existing. But
with existing stuff you need to take care. Connecting L to E of the
de-energised circuit, and then testing between the pair and Earth, (and
then only at 500V) is usually the safest bet if you are not sure what
electronic gizmos are wired into the system.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 08/08/2013 15:19, dennis@home wrote:
On 08/08/2013 11:40, tony sayer wrote:

Anyway i'm just being practical. The spec on a Wickes meter is more
than adequate for my work. I could destroy it, or a Fluke for that
matter in an instant. Whats wrong with the cable on a Wickes meter
incidentally? What was wrong with the insulation on a two for four
quid Maplin DMM by the way. What is so critical about the rating of
the cables and what do I look for when buying same?
Well we need a meter for field use that can handle measurement of very
small currents and voltages and at the same time can check the incoming
mains supplies which are very "stiff" and I wouldn't like to trust a 10
quid or otherwise device across that sort of power!. Its quite easy to
forget to take the leads of the amps measurement range when your
checking three phase supplies;!.

I expect this will be fine for most DIY use.

http://www.lidl.co.uk/cps/rde/SID-AF...l&id=4807&ar=3

Plenty good enough for most non mains work certainly.

For mains tests, it claims to be Cat II and does have a standards body
stamp on the front. So for measurements in mains appliances that are
connected at least 10m away from the CU it should be safe enough.

(Inadequate for anything in the CU or on a very stiff supply though
obviously).

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, August 8, 2013 4:19:35 PM UTC+2, dennis@home wrote:
On 08/08/2013 11:40, tony sayer wrote:



Anyway i'm just being practical. The spec on a Wickes meter is more

than adequate for my work. I could destroy it, or a Fluke for that

matter in an instant. Whats wrong with the cable on a Wickes meter

incidentally? What was wrong with the insulation on a two for four

quid Maplin DMM by the way. What is so critical about the rating of

the cables and what do I look for when buying same?

Well we need a meter for field use that can handle measurement of very

small currents and voltages and at the same time can check the incoming

mains supplies which are very "stiff" and I wouldn't like to trust a 10

quid or otherwise device across that sort of power!. Its quite easy to

forget to take the leads of the amps measurement range when your

checking three phase supplies;!.



I expect this will be fine for most DIY use.


Until it goes on the blink. IME these cheapo meters don't last 5 minutes.
I've decided to buy a seperate meter for domestic electricity and will continue to study what's on the market. In the mean time, to replace my old White Gold meter from Maplin, I popped into my local Maplin store (better the devil you know) and bought one of these by UNI-T. They're a chinese outfit, but they make digital storage scopes so should know what they're doing:

http://www.maplin.co.uk/ut60e-rms-au...nterface-46458

I do hope it doesn't turn out to be a pile of ****.

On Thursday, August 8, 2013 6:09:55 PM UTC+2, John Rumm wrote:
On 08/08/2013 15:19, dennis@home wrote:

On 08/08/2013 11:40, tony sayer wrote:



Anyway i'm just being practical. The spec on a Wickes meter is more

than adequate for my work. I could destroy it, or a Fluke for that

matter in an instant. Whats wrong with the cable on a Wickes meter

incidentally? What was wrong with the insulation on a two for four

quid Maplin DMM by the way. What is so critical about the rating of

the cables and what do I look for when buying same?

Well we need a meter for field use that can handle measurement of very

small currents and voltages and at the same time can check the incoming

mains supplies which are very "stiff" and I wouldn't like to trust a 10

quid or otherwise device across that sort of power!. Its quite easy to

forget to take the leads of the amps measurement range when your

checking three phase supplies;!.



I expect this will be fine for most DIY use.



http://www.lidl.co.uk/cps/rde/SID-AF...l&id=4807&ar=3



Plenty good enough for most non mains work certainly.



For mains tests, it claims to be Cat II and does have a standards body

stamp on the front. So for measurements in mains appliances that are

connected at least 10m away from the CU it should be safe enough.



(Inadequate for anything in the CU or on a very stiff supply though

obviously).


You can measure voltages around the CU perfectly well with just a Cat 1 meter. Just wear thick rubber gloves.

http://www.maplin.co.uk/ut60e-rms-au...nterface-46458

If you hover the mouse over the picture it blows up very clearly. Clearly enough for me to now see that it's NOT auto-ranging on Current. D'oh!

On Monday, August 5, 2013 11:53:53 AM UTC+2, The Other Mike wrote:


Find a thick electrical apprentice, get an accomplice to distract him with a

mobile phone, a picture of tits, or idle talk about the x factor. Permanently

borrow the test gear he was supposed to be looking after.

I know just the chap. Only qualified a couple of months ago and ticks all the above boxes. This is the kid who told me (just before qualifying) that "even a couple of Megaohms can kill you" and he even reads Nuts and Zoo, too. Perfect!!

On Thu, 08 Aug 2013 12:57:40 +0100, John Rumm
wrote:

On 07/08/2013 21:38, Archibald wrote:
On Wed, 07 Aug 2013 17:42:13 +0100, John Rumm
wrote:

On 07/08/2013 11:37, Archibald wrote:
On Mon, 05 Aug 2013 12:56:12 +0100, John Rumm

[1] This is one of those occasions (where you may be routinely making
connections to live circuits) where you *must* get something that is
properly designed to do the job safely - that means decent input
protection, arc protection, and a HRC fuse and not a piddly little 20mm
glass one. There is some cheap kit on ebay, but I would be wary until
you have seen exactly how its constructed.

I think you'll find that those fuses are actually semiconductor rated
devices. Designed to protect the electronics.

No, you don't need HRC fuses and blast protection chambers to protect
electronics!

It's an easy trap for
the unwary to fall into though as they do look like a bog standard
ceramic in some cases.

Not sure what kind of fuse you have in mind. Most cheap meters will have
a 20mm glass cartridge fuse, inline with the current measurement ranges
(although often not the highest range). They may not even have any fuse
inline when used on other ranges.

Probably as effective as the semiconductor rated devices fitted to the
Flukes & similar. Personally I wouln't bother too much about fuses

The fuses fitted to Flukes are HRC fuses capable of interrupting fault
currents of up to 10kA. (the reason they are so 'kin expensive!)

anyway. As you state, the higher current shunts are not fused and at
the lower end of the ranges, the components often beat the fuse hands
down on the route to destruction.

Hence these meters are not suitable for making measurements on high
energy locations (e.g. inside a consumer unit)

Bilge!

You are obviously failing to comprehend the issue here. Yes any cheap
meter will give you a measurement. It might be accurate enough, the
meter might even last for years. No one is disputing that. What we are
attempting to highlight is the way it responds when an event beyond your
control subjects it to catastrophic over volt, may not be to your liking.

I use a Wickes device, glass fuse, not sure what current

[snip]

Do as you like. However my advice would be to only use a proper Cat III
or IV rated meter, when carrying out tests on high energy sources. To do
otherwise is foolish IMO.

A DIY system is hardly going to be certified by the person dealing
with it, so I would suggest anyone having a solid idea of what they
are testing, could do the job with a cheap multimeter and a few
ancilliary bits & bobs. I would have serious doubts that any DIY
practicioner would "routinely" make test connections to live circuits
incidentally. so wear & tear shouldn't be a major factor to contend
with.

I think you are missing the point. While you can make many useful tests
with a multimeter, even a cheap one, there are a number of places where
you can't do so safely.

Also how do you carry out a full RCD test, or Insulation resistance test
with a MM? You could produce a PSSC result perhaps, but would also have
difficulty measuring the earth loop impedance.

I'm not sure what newsgroup you think you are on but this is uk.d-i-y.
No I do not think I would have difficulty measuring earth loop
impedance incidentally.

I have never completed an earth loop impedance test on any of my
wiring BTW even though we have dedicated testers for the installation
personnel,

Shrug

I would doubt that many DIY people have either.

You may doubt, but it it does not stop you being wrong.

Personally now for the most part I use a none contact device, and
although the thing, like any instrument "needs interpreting", it gives
a good indication and has saved me getting a meter out on many, many
occasions.

These are fine for go/no go indications, but they don't give you a
complete set of test capabilities.

Thank you, I feel most enlightened.

That's odd, you still appear clue resistant.

Whatever way it's dressed up, testing wiring is just an application
and understanding of Ohm's law. In my experience even some of the
cheapest junk on the market will provide measurements of more than
adequate accuracy.

Indeed, and usually you will live to tell the tale, but sometimes you wont.

It isn't the test equipment! none of it's perfect and it does not

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

Next time you probe a 3 phase supply, you may wish to reflect on this
comment from the above: "Once the bus bars began to arc, the victims'
fates were sealed, as there was no turning back at that point"

Rule number one, never stick both hands in a live "box"

Rule two, remember this is a DIY NG. I'm sure my meter would also be a
little hazardous if I stuck it on a pylon!

Few people, myself included ever need to measure the incoming supply.
Again any idiot can spend a fortune on equipment, but knowing how to
use it is a different matter!


The purpose of the input protection is to protect you primarily and not
the meter. If you are taking a voltage reading close to your consumer
unit, and the meter experiences a 10kV transient, its better that it
dies in the process of blowing its fuse and popping a few MOVs, tham
allowing an arc flash to engulf the user.

Really?

Yes

Is this the same mains that all those TV's radios, table
lamps and such like are connected to?

No its not, and that is the key.

Making measurements inside a mains appliance (while that has its own
risks), does not usually expose you to a high energy source - you are
nicely buffered by a reasonable length of domestic wiring with a few
tenths of an ohm of loop impedance [1]. If things go pear shaped there
are likely to only be few hundred amps of fault current available.

Taking readings at a consumer unit may expose you to a source of many
thousands of amps of prospective short circuit currant.

Perhaps you should go on a
crusade to fit better fuses on all this equipment before the users are
engulfed in a searing hot plasma, or is there some magical barrier in
a consumenr unit that stops transients dead?

Given a working knowledge of ohms law, you should be able to work that
out for yourself.

Test equipment fuses are not semiconductor rated to protect the user!
I suppose people are "semiconductors", but they dont fit semiconductor
fuses to toasters do they? If they see fit to put the things in meters
and not toasters does it not suggest that they may not after all be
trying to protect the user?

Has it occurred to you, that the fusing in the meter may have more than
one purpose? (or for that matter, why some meters have more than one fuse?)


[1] Usually, although you might want to ask Adam what the PSCC is in his
house...

On 08/08/2013 17:29, wrote:
On Thursday, August 8, 2013 6:09:55 PM UTC+2, John Rumm wrote:
On 08/08/2013 15:19, dennis@home wrote:

On 08/08/2013 11:40, tony sayer wrote:



Anyway i'm just being practical. The spec on a Wickes meter is more

than adequate for my work. I could destroy it, or a Fluke for that

matter in an instant. Whats wrong with the cable on a Wickes meter

incidentally? What was wrong with the insulation on a two for four

quid Maplin DMM by the way. What is so critical about the rating of

the cables and what do I look for when buying same?

Well we need a meter for field use that can handle measurement of very

small currents and voltages and at the same time can check the incoming

mains supplies which are very "stiff" and I wouldn't like to trust a 10

quid or otherwise device across that sort of power!. Its quite easy to

forget to take the leads of the amps measurement range when your

checking three phase supplies;!.



I expect this will be fine for most DIY use.



http://www.lidl.co.uk/cps/rde/SID-AF...l&id=4807&ar=3



Plenty good enough for most non mains work certainly.



For mains tests, it claims to be Cat II and does have a standards body

stamp on the front. So for measurements in mains appliances that are

connected at least 10m away from the CU it should be safe enough.



(Inadequate for anything in the CU or on a very stiff supply though

obviously).


You can measure voltages around the CU perfectly well with just a Cat 1 meter. Just wear thick rubber gloves.

Do they protect your face from arc flash injury? (its not the shock risk
you need to worry about in these cases!)


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On 08/08/2013 19:28, Archibald wrote:
On Thu, 08 Aug 2013 12:57:40 +0100, John Rumm
wrote:

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

Next time you probe a 3 phase supply, you may wish to reflect on this
comment from the above: "Once the bus bars began to arc, the victims'
fates were sealed, as there was no turning back at that point"

Rule number one, never stick both hands in a live "box"

Sometimes it is not avoidable - especially if you need to work at a
consumer unit. Note also that even a socket on a circuit close to a CU
can pose a high energy source risk in some circumstances.

Rule two, remember this is a DIY NG. I'm sure my meter would also be a
little hazardous if I stuck it on a pylon!

The cases where you will need a class IV meter are indeed likely to be
few for a DIY situation. However there are plenty of situations where a
class III device may one be required. A causal acquaintance with this
group should furnish you with enough examples of domestic situations
where people here have measured supply impedances below the resolution
of their equipment (i.e. an indicated zero ohms)

Few people, myself included ever need to measure the incoming supply.
Again any idiot can spend a fortune on equipment, but knowing how to
use it is a different matter!

True but not really relevant, since we are discussing the idiots who
should be spending more on test equipment, but choose to wing it with
substandard gear.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thu, 08 Aug 2013 12:57:40 +0100, John Rumm
wrote:

On 07/08/2013 21:38, Archibald wrote:
On Wed, 07 Aug 2013 17:42:13 +0100, John Rumm
wrote:

On 07/08/2013 11:37, Archibald wrote:
On Mon, 05 Aug 2013 12:56:12 +0100, John Rumm

[1] This is one of those occasions (where you may be routinely making
connections to live circuits) where you *must* get something that is
properly designed to do the job safely - that means decent input
protection, arc protection, and a HRC fuse and not a piddly little 20mm
glass one. There is some cheap kit on ebay, but I would be wary until
you have seen exactly how its constructed.

I think you'll find that those fuses are actually semiconductor rated
devices. Designed to protect the electronics.

No, you don't need HRC fuses and blast protection chambers to protect
electronics!

It's an easy trap for
the unwary to fall into though as they do look like a bog standard
ceramic in some cases.

Not sure what kind of fuse you have in mind. Most cheap meters will have
a 20mm glass cartridge fuse, inline with the current measurement ranges
(although often not the highest range). They may not even have any fuse
inline when used on other ranges.

Probably as effective as the semiconductor rated devices fitted to the
Flukes & similar. Personally I wouln't bother too much about fuses

The fuses fitted to Flukes are HRC fuses capable of interrupting fault
currents of up to 10kA. (the reason they are so 'kin expensive!)

anyway. As you state, the higher current shunts are not fused and at
the lower end of the ranges, the components often beat the fuse hands
down on the route to destruction.

Hence these meters are not suitable for making measurements on high
energy locations (e.g. inside a consumer unit)

Bilge!

You are obviously failing to comprehend the issue here. Yes any cheap
meter will give you a measurement. It might be accurate enough, the
meter might even last for years. No one is disputing that. What we are
attempting to highlight is the way it responds when an event beyond your
control subjects it to catastrophic over volt, may not be to your liking.

I use a Wickes device, glass fuse, not sure what current

[snip]

Do as you like. However my advice would be to only use a proper Cat III
or IV rated meter, when carrying out tests on high energy sources. To do
otherwise is foolish IMO.

A DIY system is hardly going to be certified by the person dealing
with it, so I would suggest anyone having a solid idea of what they
are testing, could do the job with a cheap multimeter and a few
ancilliary bits & bobs. I would have serious doubts that any DIY
practicioner would "routinely" make test connections to live circuits
incidentally. so wear & tear shouldn't be a major factor to contend
with.

I think you are missing the point. While you can make many useful tests
with a multimeter, even a cheap one, there are a number of places where
you can't do so safely.

Also how do you carry out a full RCD test, or Insulation resistance test
with a MM? You could produce a PSSC result perhaps, but would also have
difficulty measuring the earth loop impedance.

I'm not sure what newsgroup you think you are on but this is uk.d-i-y.
No I do not think I would have difficulty measuring earth loop
impedance incidentally.

I have never completed an earth loop impedance test on any of my
wiring BTW even though we have dedicated testers for the installation
personnel,

Shrug

I would doubt that many DIY people have either.

You may doubt, but it it does not stop you being wrong.

Personally now for the most part I use a none contact device, and
although the thing, like any instrument "needs interpreting", it gives
a good indication and has saved me getting a meter out on many, many
occasions.

These are fine for go/no go indications, but they don't give you a
complete set of test capabilities.

Thank you, I feel most enlightened.

That's odd, you still appear clue resistant.

Whatever way it's dressed up, testing wiring is just an application
and understanding of Ohm's law. In my experience even some of the
cheapest junk on the market will provide measurements of more than
adequate accuracy.

Indeed, and usually you will live to tell the tale, but sometimes you wont.

It isn't the test equipment! none of it's perfect and it does not

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

This is a DIY NG. The scenario described is outside my and I'm sure
many others scope of work in this NG.

Next time you probe a 3 phase supply, you may wish to reflect on this
comment from the above: "Once the bus bars began to arc, the victims'
fates were sealed, as there was no turning back at that point"

The purpose of the input protection is to protect you primarily and not
the meter. If you are taking a voltage reading close to your consumer
unit, and the meter experiences a 10kV transient, its better that it
dies in the process of blowing its fuse and popping a few MOVs, tham
allowing an arc flash to engulf the user.

Really?

Yes

Is this the same mains that all those TV's radios, table
lamps and such like are connected to?

No its not, and that is the key.

Making measurements inside a mains appliance (while that has its own
risks), does not usually expose you to a high energy source - you are
nicely buffered by a reasonable length of domestic wiring with a few
tenths of an ohm of loop impedance [1]. If things go pear shaped there
are likely to only be few hundred amps of fault current available.

Taking readings at a consumer unit may expose you to a source of many
thousands of amps of prospective short circuit currant.

Perhaps you should go on a
crusade to fit better fuses on all this equipment before the users are
engulfed in a searing hot plasma, or is there some magical barrier in
a consumenr unit that stops transients dead?

Given a working knowledge of ohms law, you should be able to work that
out for yourself.

Sadly, no. Perhaps you caqn enlighten?

Test equipment fuses are not semiconductor rated to protect the user!
I suppose people are "semiconductors", but they dont fit semiconductor
fuses to toasters do they? If they see fit to put the things in meters
and not toasters does it not suggest that they may not after all be
trying to protect the user?

Has it occurred to you, that the fusing in the meter may have more than
one purpose? (or for that matter, why some meters have more than one fuse?)


[1] Usually, although you might want to ask Adam what the PSCC is in his
house...

AB

On 08/08/2013 17:29, wrote:

You can measure voltages around the CU perfectly well with just a Cat
1 meter. Just wear thick rubber gloves.


Its something to protect you from the leads as they vapourise that you need.

There isn't much chance of anything happening if you know what you are
doing.

On Thursday, August 8, 2013 11:33:48 PM UTC+2, dennis@home wrote:
On 08/08/2013 17:29, wrote:



You can measure voltages around the CU perfectly well with just a Cat

1 meter. Just wear thick rubber gloves.





Its something to protect you from the leads as they vapourise that you need.



There isn't much chance of anything happening if you know what you are

doing.

I'm safe. I've got the same type of rubber gloves that vets use when they're feeling around for calves.

On 8 Aug 2013 13:43:26 GMT, Bob Eager wrote:

On Thu, 08 Aug 2013 13:17:36 +0100, The Other Mike wrote:

On 7 Aug 2013 21:16:29 GMT, Bob Eager wrote:

On Wed, 07 Aug 2013 21:38:33 +0100, Archibald wrote:

Incidentally, years back I had an AVO eight, the industry standard
hyper priced instrument of my youth. I dont even think it was fused.

They have a fuse, and a cut-out.

Not 100% sure about a fuse as its so long since I've used one or had one
apart but definitely agree on the cutout.

It's in the battery compartment - on all marks of the 8 as far as I know
(I have a Mark 1, a Mark 3 and a Mark 7 here).

There is no way they would be permitted to be used for field
measurements on any mains fed equipment in any establishment with even
the slightest hint of a safety culture.

Why not?

The unshrouded terminals and lack of formal testing to to IEC 61010 / BS 61010


--

On 08/08/2013 22:17, Archibald wrote:
On Thu, 08 Aug 2013 12:57:40 +0100, John Rumm
wrote:

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

This is a DIY NG. The scenario described is outside my and I'm sure
many others scope of work in this NG.

I am not sure why you think it is any different for a domestic
environment. Domestic environments still have supplies that are high
energy (especially in large towns, and for those living close to their
substation), and still require equipment with a Cat III rating when
working close to them. The risk from transient over voltage is the same,
or in some cases higher (e.g. where the LV supply is via overhead wires).

Have a look at page 2:

http://www.myflukestore.com/crm_uplo...ation_note.pdf

The difference between cat II and III kit is fairly clearly explained.

Open a meter and look at the construction of a certified CAT III device,
and then compare with some of the budget devices that also claims the
same rating, but are not independently tested or certified. The
difference can be substantial.

Now if you are comfortable working on high energy parts of a domestic
installation using a basic multimeter that has not been designed for
electrical installation testing, and does not have the recommended level
of input protection, then by all means carry on, its your choice.
Hopefully this discussion has made it clear to other readers that there
are risks related to using inappropriate equipment, and now they are
also it a position to make the same informed decision.

There are various tests required for electrical work laid out in BS 7671
(the wiring regs) that you won't be able to conduct at all using a
normal multimeter, and there are some others that you can do, but they
will require more effort, and take longer. Either way, you will need to
decide if the effort / cost trade off it worth it, and also accept you
may nott be able to prove that your work is up to the required standard.
Again, if this does not concern you, carry on.

Taking readings at a consumer unit may expose you to a source of many
thousands of amps of prospective short circuit currant.

Perhaps you should go on a
crusade to fit better fuses on all this equipment before the users are
engulfed in a searing hot plasma, or is there some magical barrier in
a consumenr unit that stops transients dead?

Given a working knowledge of ohms law, you should be able to work that
out for yourself.

Sadly, no. Perhaps you caqn enlighten?

A consumer unit does not stop transients (although you will get a slight
snubbing effect from the magnetic coil in the MCB). Hence it is possible
to drive your test equipment into a failure inducing overvolt by
connecting it at any point in a system.

What does change the further you move from the origin of the supply in a
building, is the prospective short circuit current and the prospective
fault current. Both fall as a result of the increasing loop and supply
impedance (also the temperature rise introduced when small CSA wiring is
driven into adiabatic heating under fault conditions, adds additional
resistance). These factors conspire to make arc flash very much less
likely in the first place, and far less damaging should it actually happen.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, 8 August 2013 21:45:34 UTC+2, John Rumm wrote:
On 08/08/2013 17:29, wrote:

On Thursday, August 8, 2013 6:09:55 PM UTC+2, John Rumm wrote:

On 08/08/2013 15:19, dennis@home wrote:



On 08/08/2013 11:40, tony sayer wrote:







Anyway i'm just being practical. The spec on a Wickes meter is more



than adequate for my work. I could destroy it, or a Fluke for that



matter in an instant. Whats wrong with the cable on a Wickes meter



incidentally? What was wrong with the insulation on a two for four



quid Maplin DMM by the way. What is so critical about the rating of



the cables and what do I look for when buying same?



Well we need a meter for field use that can handle measurement of very



small currents and voltages and at the same time can check the incoming



mains supplies which are very "stiff" and I wouldn't like to trust a 10



quid or otherwise device across that sort of power!. Its quite easy to



forget to take the leads of the amps measurement range when your



checking three phase supplies;!.







I expect this will be fine for most DIY use.







http://www.lidl.co.uk/cps/rde/SID-AF...l&id=4807&ar=3







Plenty good enough for most non mains work certainly.







For mains tests, it claims to be Cat II and does have a standards body



stamp on the front. So for measurements in mains appliances that are



connected at least 10m away from the CU it should be safe enough.







(Inadequate for anything in the CU or on a very stiff supply though



obviously).





You can measure voltages around the CU perfectly well with just a Cat 1 meter. Just wear thick rubber gloves.



Do they protect your face from arc flash injury? (its not the shock risk

you need to worry about in these cases!)

OK, then how about one of those old fashioned diver's suits - the ones with the brass fishbowl helmet and lead boots? Will that suffice?

In article , The Other Mike
scribeth thus
On Wed, 7 Aug 2013 22:03:48 +0100, tony sayer wrote:

So your working on those sorts of systems and are that tight to buy a
half decent pro meter?.

It can't be in any professional capacity, or if it is H&S has clearly gone out
of the window.

You can get good Fluke meters on e-bay for
around 40 to 50 quid sometimes.

No need to even buy secondhand at the moment, Fluke 113 £84 quid NEW (that is
probably plus VAT)

http://www.fluke.com/fluke/uken/wher...i/65_years.htm



Very good pricing there, but the meters I have are fine as there're good
quality ones they do last well...


CATIV 300V, CATIII 600V

Buggered if I'd use a cheap chinkie one of dubious origin;!...

Absolutely, although quite a few Flukes, including this 113 are made in China
now.


Well if the design is right the components are the Same it matters not
where they make them. I suppose there're made by machines for the
greater part?..

--
Tony Sayer

On 09/08/2013 18:47, wrote:


OK, then how about one of those old fashioned diver's suits - the
ones with the brass fishbowl helmet and lead boots? Will that
suffice?

You might look a bit of a prawn ;-)

Something like:

http://www.coleparmer.co.uk/Product/...fJtAodB2EA hQ

and a flame retardant jacket is more the norm when working on
particularly risky situations.



--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Thursday, 8 August 2013 17:19:11 UTC+1, wrote:
On Thursday, August 8, 2013 4:19:35 PM UTC+2, dennis@home wrote:

On 08/08/2013 11:40, tony sayer wrote:







Anyway i'm just being practical. The spec on a Wickes meter is more



than adequate for my work. I could destroy it, or a Fluke for that



matter in an instant. Whats wrong with the cable on a Wickes meter



incidentally? What was wrong with the insulation on a two for four



quid Maplin DMM by the way. What is so critical about the rating of



the cables and what do I look for when buying same?



Well we need a meter for field use that can handle measurement of very



small currents and voltages and at the same time can check the incoming



mains supplies which are very "stiff" and I wouldn't like to trust a 10



quid or otherwise device across that sort of power!. Its quite easy to



forget to take the leads of the amps measurement range when your



checking three phase supplies;!.







I expect this will be fine for most DIY use.





Until it goes on the blink. IME these cheapo meters don't last 5 minutes.

I've decided to buy a seperate meter for domestic electricity and will continue to study what's on the market. In the mean time, to replace my old White Gold meter from Maplin, I popped into my local Maplin store (better the devil you know) and bought one of these by UNI-T. They're a chinese outfit, but they make digital storage scopes so should know what they're doing:



http://www.maplin.co.uk/ut60e-rms-au...nterface-46458



I do hope it doesn't turn out to be a pile of ****.

From the UT60E manual:

( http://www.uni-trend.com/manual2/UT6...g%20Manual.pdf )

This Meter complies with the standards IEC61010: in
pollution degree 2, overvoltage category (CAT. III 1000V,
CAT. IV 600Vand double insulation.
CAT. III: Distribution level, fixed installation, with smaller
transient overvoltages than CAT. IV
CAT IV: Primary supply level, overhead lines, cable
systems etc.

However internal photos he

( http://www.flickr.com/photos/2200869...7625829258944/ )

Show non-HRC fuses.

http://www.maplin.co.uk/ut60e-rms-au...meter-with-pc-
interface-46458



I do hope it doesn't turn out to be a pile of ****.

From the UT60E manual:

( http://www.uni-trend.com/manual2/UT6...g%20Manual.pdf )

This Meter complies with the standards IEC61010: in
pollution degree 2, overvoltage category (CAT. III 1000V,
CAT. IV 600Vand double insulation.
CAT. III: Distribution level, fixed installation, with smaller
transient overvoltages than CAT. IV
CAT IV: Primary supply level, overhead lines, cable
systems etc.

However internal photos he

( http://www.flickr.com/photos/2200869...7625829258944/ )

Show non-HRC fuses.


Shouldn't there be some certification from an approval body to support
that?..

--
Tony Sayer

Shouldn't there be some certification from an approval body to support

that?..


Read John Rumm's link to the article by Fluke. There's a body that sets the Class I-IV standard, but it's up to the manufacturer to self-certify compliance.

On Tuesday, 6 August 2013 11:42:12 UTC+1, wrote:
Anyone heard of this outfit? They have a peruseworthy range of meters. What does this erudite panel think of their wares?



http://testinstrumentsolutions.co.uk/

I'm not certain, but the red and black stuff looks a lot like UNI-T http://www.uni-trend.com/product.html

On Fri, 09 Aug 2013 15:59:41 +0100, John Rumm
wrote:

On 08/08/2013 22:17, Archibald wrote:
On Thu, 08 Aug 2013 12:57:40 +0100, John Rumm
wrote:

Please read:

http://ecmweb.com/arc-flash/case-deadly-arc-flash

This is a DIY NG. The scenario described is outside my and I'm sure
many others scope of work in this NG.

I am not sure why you think it is any different for a domestic
environment. Domestic environments still have supplies that are high
energy (especially in large towns, and for those living close to their
substation), and still require equipment with a Cat III rating when
working close to them. The risk from transient over voltage is the same,
or in some cases higher (e.g. where the LV supply is via overhead wires).

Have a look at page 2:

http://www.myflukestore.com/crm_uplo...ation_note.pdf

The difference between cat II and III kit is fairly clearly explained.

Open a meter and look at the construction of a certified CAT III device,
and then compare with some of the budget devices that also claims the
same rating, but are not independently tested or certified. The
difference can be substantial.

Now if you are comfortable working on high energy parts of a domestic
installation using a basic multimeter that has not been designed for
electrical installation testing, and does not have the recommended level
of input protection, then by all means carry on, its your choice.
Hopefully this discussion has made it clear to other readers that there
are risks related to using inappropriate equipment, and now they are
also it a position to make the same informed decision.

There are various tests required for electrical work laid out in BS 7671
(the wiring regs) that you won't be able to conduct at all using a
normal multimeter, and there are some others that you can do, but they
will require more effort, and take longer. Either way, you will need to
decide if the effort / cost trade off it worth it, and also accept you
may nott be able to prove that your work is up to the required standard.
Again, if this does not concern you, carry on.

Taking readings at a consumer unit may expose you to a source of many
thousands of amps of prospective short circuit currant.

Perhaps you should go on a
crusade to fit better fuses on all this equipment before the users are
engulfed in a searing hot plasma, or is there some magical barrier in
a consumenr unit that stops transients dead?

Given a working knowledge of ohms law, you should be able to work that
out for yourself.

Sadly, no. Perhaps you caqn enlighten?

A consumer unit does not stop transients (although you will get a slight
snubbing effect from the magnetic coil in the MCB). Hence it is possible
to drive your test equipment into a failure inducing overvolt by
connecting it at any point in a system.

What does change the further you move from the origin of the supply in a
building, is the prospective short circuit current and the prospective
fault current. Both fall as a result of the increasing loop and supply
impedance (also the temperature rise introduced when small CSA wiring is
driven into adiabatic heating under fault conditions, adds additional
resistance). These factors conspire to make arc flash very much less
likely in the first place, and far less damaging should it actually happen.

I'm afraid the difference of a few mOhms due to heating effects would
not really change my approach or assesment of the risks involved.

A DMM has an input impedance of 10MOhm or thereabouts. I'm sure the
spike produced by the introduction of such a load would have world
changing repercussions!




Someone carrying out DIY work can do it without the aid of a £100-00
DMM. I have yet to find a job that my Wickes DMM wasn't suitable for
and that includes for professional use. In fact the only problem I
might have on a site is the use of a "not calibrated for indication
only" label. Apart from this it is an acceptable tool! As I stated
before, any idiot can spend a fortune on test equipment, but that does
not mean they can use it correctly.

There are a few little rules your flight of fancy does not take into
account incidentally. No one should work live if it's avoidable. There
are none contact measures available to indicate voltage and anyone
sticking both hands inside a piece of live apparatus even with the
fingerproof terminals in current use would need a serious amount of
reprogramming.

The other point you may care to consider is that many " professional"
meters The Flukes I used included, do not have a fuse for the higher
current ranges. Although different sockets and interlocks are
available, this does not allow for operator error. I'm not sure what
would make the most effective fuse at that point, the shunt or the
test leads.

On a final note, I consider one of the most serious ommissions from
any meter now is the crock clip. I never ever did work two handed and
do not feel comfortable doing so now, it seems strange however with
todays safety culture you are forced into chinese restaurant mode to
measure aross a couple of terminals.


On a final note do you actually connect equipment up to this
phenomenally unstable supply the Electricity board provides?

I find it amazing that entire streets are not going down due to these
"transients".

Do you sell extension sockets or UPS for a living BTW?

AB

On Saturday, 10 August 2013 08:15:13 UTC+2, wrote:
On Thursday, 8 August 2013 17:19:11 UTC+1, wrote:

On Thursday, August 8, 2013 4:19:35 PM UTC+2, dennis@home wrote:



On 08/08/2013 11:40, tony sayer wrote:















Anyway i'm just being practical. The spec on a Wickes meter is more







than adequate for my work. I could destroy it, or a Fluke for that







matter in an instant. Whats wrong with the cable on a Wickes meter







incidentally? What was wrong with the insulation on a two for four







quid Maplin DMM by the way. What is so critical about the rating of







the cables and what do I look for when buying same?







Well we need a meter for field use that can handle measurement of very







small currents and voltages and at the same time can check the incoming







mains supplies which are very "stiff" and I wouldn't like to trust a 10







quid or otherwise device across that sort of power!. Its quite easy to







forget to take the leads of the amps measurement range when your







checking three phase supplies;!.















I expect this will be fine for most DIY use.











Until it goes on the blink. IME these cheapo meters don't last 5 minutes.



I've decided to buy a seperate meter for domestic electricity and will continue to study what's on the market. In the mean time, to replace my old White Gold meter from Maplin, I popped into my local Maplin store (better the devil you know) and bought one of these by UNI-T. They're a chinese outfit, but they make digital storage scopes so should know what they're doing:







http://www.maplin.co.uk/ut60e-rms-au...nterface-46458







I do hope it doesn't turn out to be a pile of ****.



From the UT60E manual:



( http://www.uni-trend.com/manual2/UT6...g%20Manual.pdf )



This Meter complies with the standards IEC61010: in

pollution degree 2, overvoltage category (CAT. III 1000V,

CAT. IV 600Vand double insulation.

CAT. III: Distribution level, fixed installation, with smaller

transient overvoltages than CAT. IV

CAT IV: Primary supply level, overhead lines, cable

systems etc.



However internal photos he



( http://www.flickr.com/photos/2200869...7625829258944/ )



Show non-HRC fuses.

Thanks for the heads up. I will whip the lid off when it arrives and will be having serious words with Maplin if it turns out so.

On Saturday, 10 August 2013 12:46:16 UTC+1, wrote:
On Saturday, 10 August 2013 08:15:13 UTC+2, wrote:

On Thursday, 8 August 2013 17:19:11 UTC+1, wrote:



On Thursday, August 8, 2013 4:19:35 PM UTC+2, dennis@home wrote:







On 08/08/2013 11:40, tony sayer wrote:































Anyway i'm just being practical. The spec on a Wickes meter is more















than adequate for my work. I could destroy it, or a Fluke for that















matter in an instant. Whats wrong with the cable on a Wickes meter















incidentally? What was wrong with the insulation on a two for four















quid Maplin DMM by the way. What is so critical about the rating of















the cables and what do I look for when buying same?















Well we need a meter for field use that can handle measurement of very















small currents and voltages and at the same time can check the incoming















mains supplies which are very "stiff" and I wouldn't like to trust a 10















quid or otherwise device across that sort of power!. Its quite easy to















forget to take the leads of the amps measurement range when your















checking three phase supplies;!.































I expect this will be fine for most DIY use.























Until it goes on the blink. IME these cheapo meters don't last 5 minutes.







I've decided to buy a seperate meter for domestic electricity and will continue to study what's on the market. In the mean time, to replace my old White Gold meter from Maplin, I popped into my local Maplin store (better the devil you know) and bought one of these by UNI-T. They're a chinese outfit, but they make digital storage scopes so should know what they're doing:















http://www.maplin.co.uk/ut60e-rms-au...nterface-46458















I do hope it doesn't turn out to be a pile of ****.







From the UT60E manual:







( http://www.uni-trend.com/manual2/UT6...g%20Manual.pdf )







This Meter complies with the standards IEC61010: in



pollution degree 2, overvoltage category (CAT. III 1000V,



CAT. IV 600Vand double insulation.



CAT. III: Distribution level, fixed installation, with smaller



transient overvoltages than CAT. IV



CAT IV: Primary supply level, overhead lines, cable



systems etc.







However internal photos he







( http://www.flickr.com/photos/2200869...7625829258944/ )







Show non-HRC fuses.



Thanks for the heads up. I will whip the lid off when it arrives and will be having serious words with Maplin if it turns out so.

I own a UNI-T multitester ( http://www.uni-trend.com/UT526.html ) and for the price I'm quite happy with it. In all the ways I've been able to test it, it seems to perform to it's stated spec. But I'm using it either as an insulation tester or low-ohm meter. That has safety implications, but less so than probing into a live high-energy system.

Maybe they've found a way to make your meter Class III without requiring HRC fuses. Realistically, Maplin isn't in a position to check every claim on every product they sell, and has to trust its suppliers.

I see both sides of the arguments advanced here. As John Rumm says, for serious work, it's a real safety concern. As others say, for very occasionally probing inside a CU - you would be phenomenally unlucky to come to grief.