Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before I cut into it. It seems to detect voltage but when I switched the circuit off it still seems to think there is voltage although the beep / led is not continuous. I know the socket is off as I had something plugged into it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power button and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do the self test thing. Brought a new one home to test on the off circuit and same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now thinking maybe I am missing something?

Thanks

Lee.

wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before I cut into it. It seems to detect voltage but when I switched the circuit off it still seems to think there is voltage although the beep / led is not continuous. I know the socket is off as I had something plugged into it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power button and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do the self test thing. Brought a new one home to test on the off circuit and same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now thinking maybe I am missing something?

Thanks

Lee.

They use an unsound principle and cannot be relied on. Don't buy

On 03/12/2017 15:24, wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before I cut into it. It seems to detect voltage but when I switched the circuit off it still seems to think there is voltage although the beep / led is not continuous. I know the socket is off as I had something plugged into it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power button and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do the self test thing. Brought a new one home to test on the off circuit and same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now thinking maybe I am missing something?

Thanks

Lee.

I'd go with a bad batch; what did Screwfix say? You should post feedback
on their web site. Never had one with self test (could be a bad
instruction leaflet)? The false positive sounds like it might result
from inductive coupling with a parallel circuit. You sometimes see this
with neon screwdrivers and DVMs, although I've never seen it with a
"volt stick".

What I like about volt sticks is that they can often be used to
distinguish non-invasively between a plug fuse failure, a line switch
failure, or load device failure.

One thing I forgot to mention is that the first one was from a different Screwfix branch. doesn't preclude the bad batch theory though. The only reason I wanted this is to quadruple check I have the correct wire before breaking in to it. The wiring for first floor is a little odd as most sockets are fed from below but for some reason this one seems to be fed from above although it is on the correct circuit. Hence I want to be extra sure I have the correct wire before cutting.

On 03/12/2017 15:42, newshound wrote:

The false positive sounds like it might result
from inductive coupling with a parallel circuit. You sometimes see this
with neon screwdrivers and DVMs, although I've never seen it with a
"volt stick".


Surely more likely with a contactLESS device as is this volts stick


--
--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 03/12/2017 15:37, Bob Minchin wrote:
wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869


Reviews seemed good only needed it to confirm circuit is off before I
cut into it. It seems to detect voltage but when I switched the
circuit off it still seems to think there is voltage although the beep
/ led is not continuous. I know the socket is off as I had something
plugged into it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power
button and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do
the self test thing. Brought a new one home to test on the off circuit
and same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now
thinking maybe I am missing something?

Thanks

Lee.

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

--
Robin
reply-to address is (intended to be) valid

On Sunday, 3 December 2017 16:47:12 UTC, Robin wrote:
On 03/12/2017 15:37, Bob Minchin wrote:
wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869


Reviews seemed good only needed it to confirm circuit is off before I
cut into it. It seems to detect voltage but when I switched the
circuit off it still seems to think there is voltage although the beep
/ led is not continuous. I know the socket is off as I had something
plugged into it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power
button and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do
the self test thing. Brought a new one home to test on the off circuit
and same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now
thinking maybe I am missing something?

Thanks

Lee.

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


NT

If this type is so unreliable what is the safest way to determine if a cable is safe to cut?

On 03/12/2017 17:28, wrote:
They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

--
Robin
reply-to address is (intended to be) valid

On Sunday, 3 December 2017 17:31:31 UTC, wrote:
If this type is so unreliable what is the safest way to determine if a cable is safe to cut?

voltmeter


NT

On Sun, 3 Dec 2017 09:41:40 -0800 (PST)
wrote:

On Sunday, 3 December 2017 17:31:31 UTC, wrote:
If this type is so unreliable what is the safest way to determine
if a cable is safe to cut?

voltmeter


What if there's no neutral, either missing (fault), or unavailable
(switch drop)? Possibly no earth either, in the case of a switch drop
wired in singles.

On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

it isn't, it's just false positives. Come back when you understand them.


NT

In article ,
Mike Hunt wrote:
On Sun, 3 Dec 2017 09:41:40 -0800 (PST)
wrote:

On Sunday, 3 December 2017 17:31:31 UTC, wrote:
If this type is so unreliable what is the safest way to determine
if a cable is safe to cut?

voltmeter


What if there's no neutral, either missing (fault), or unavailable
(switch drop)? Possibly no earth either, in the case of a switch drop
wired in singles.


use an extension lead

--
from KT24 in Surrey, England

On Sun, 3 Dec 2017 10:06:59 -0800 (PST), wrote:

As for false positives, I take it you mean the way they will
detect voltages which are totally safe for human contact. On
the whole I prefer to see that not so much a false positive as
an indication of the need to check further.

it isn't, it's just false positives. Come back when you
understand them.

In this case it seems a question of what is positive and what is
negative - the presence of mains voltage as a result of the test
could be taken either way.

wrote:
On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is
a hazard


I'm well aware of the possibility of a false negative with them (as
with any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of
the need to check further.

it isn't, it's just false positives. Come back when you understand
them.

Years ago I was given one of those gadgets. It was dead posh and detected
voltage in the walls where I knew there were wires.
Then it tried to tell me that there was voltage in the lounge door!
I recently bought a volt stick to detect voltage should I have a broken wire
in the vac cleaner etc. That is about they are good for.

A volt meter will only be useful once you have cut into the cable. In my situation I want to prove that a cable is part of a particular circuit and is off

Mike Hunt wrote
wrote
wrote

If this type is so unreliable what is the safest
way to determine if a cable is safe to cut?

voltmeter

What if there's no neutral, either missing (fault), or unavailable (switch
drop)?

Use an extension cord to a GPO to get one.

Possibly no earth either, in the case of a switch drop wired in singles.

Ditto.

wrote

A volt meter will only be useful once you have cut into the cable.

Thats not true if you use a probe that has the equivalent
of a pin at the end that you can stick true the insulation.

In my situation I want to prove that a cable
is part of a particular circuit and is off

That sort of probe will do that.

On Sun, 03 Dec 2017 19:29:43 -0000, Birdbrain Macaw (now "James Wilkinson"),
the pathological attention whore of all the uk ngs, blathered again:

Years ago I was given one of those gadgets. It was dead posh and detected
voltage in the walls where I knew there were wires.
Then it tried to tell me that there was voltage in the lounge door!
I recently bought a volt stick to detect voltage should I have a broken wire
in the vac cleaner etc. That is about they are good for.

One of those things worked out which Christmas tree bulb had failed.
Apart from that they're utterly useless.

IOW, they are exactly like YOU, Birdbrain!

--
More of Birdbrain Macaw's (now "James Wilkinson" LOL) "wisdom":
"Look at a donkey with a 2 foot penis. Does it require underwear? No."
MID:

wrote:
A volt meter will only be useful once you have cut into the cable. In my
situation I want to prove that a cable is part of a particular circuit
and is off

I don't believe you can do that certainly without having a physical
connection to the wire involved. I'd certainly not want to rely on
something that detects the (weak) radiated field from the wire.

--
Chris Green
·

On 03/12/2017 18:06, wrote:
On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

it isn't, it's just false positives. Come back when you understand them.


I'd be more impressed by your confidence if you'd bothered to state what
you are taking to be the purpose of a volt stick. (Note I never said I
approved the use of a volt stick to prove a conductor "dead". I do
continue to fail to see why you claim they are "always unsound in
principle" to identify a live conductor - eg when there are several
conductors in a conduit.)


--
Robin
reply-to address is (intended to be) valid

On Sunday, 3 December 2017 18:31:47 UTC, mechanic wrote:
On Sun, 3 Dec 2017 10:06:59 -0800 (PST), tabbypurr wrote:

As for false positives, I take it you mean the way they will
detect voltages which are totally safe for human contact. On
the whole I prefer to see that not so much a false positive as
an indication of the need to check further.

it isn't, it's just false positives. Come back when you
understand them.

In this case it seems a question of what is positive and what is
negative - the presence of mains voltage as a result of the test
could be taken either way.

I see the idiot's back

On Sunday, 3 December 2017 19:20:36 UTC, wrote:
A volt meter will only be useful once you have cut into the cable. In my situation I want to prove that a cable is part of a particular circuit and is off

You must be using yours differently to what I do


NT

On Sunday, 3 December 2017 19:31:53 UTC, James Wilkinson Sword wrote:

Detecting voltage without actually touching the wire doesn't work. Even if you take a voltmeter and place the red wire on a live, and the black wire on ground, or your finger, you can get a voltage reading even if no voltage is present, due to induction. These things can't tell the difference between a bit of induced voltage and 240V with current carrying capabilities.

depends on the meter. That's not normally a problem


NT

On Sunday, 3 December 2017 21:35:32 UTC, Robin wrote:
On 03/12/2017 18:06, tabbypurr wrote:
On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

it isn't, it's just false positives. Come back when you understand them.


I'd be more impressed by your confidence if you'd bothered to state what
you are taking to be the purpose of a volt stick.

to detect voltage?

(Note I never said I
approved the use of a volt stick to prove a conductor "dead". I do
continue to fail to see why you claim they are "always unsound in
principle" to identify a live conductor - eg when there are several
conductors in a conduit.)

you could always read up on how they work and why they give false negatives and false positives.


NT

On Sunday, 3 December 2017 21:33:05 UTC, Chris Green wrote:
wrote:
A volt meter will only be useful once you have cut into the cable. In my
situation I want to prove that a cable is part of a particular circuit
and is off

I don't believe you can do that certainly without having a physical
connection to the wire involved. I'd certainly not want to rely on
something that detects the (weak) radiated field from the wire.

You can and it's easy enough, but I no of no product that does it.


NT

On 03/12/2017 17:41, wrote:
On Sunday, 3 December 2017 17:31:31 UTC, wrote:
If this type is so unreliable what is the safest way to determine if a cable is safe to cut?

voltmeter

Not exactly "non contract" though is it!


--
Cheers,

John.

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

On 03/12/2017 15:24, wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before
I cut into it. It seems to detect voltage but when I switched the
circuit off it still seems to think there is voltage although the
beep / led is not continuous. I know the socket is off as I had
something plugged into it which then went off when I switched the
circuit off.

Are you saying the indication you got from the live and dead circuits
were the same, or was the "dead" reading "different" but not quite what
you expected?


--
Cheers,

John.

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

On Mon, 04 Dec 2017 00:10:01 +0000, John Rumm wrote:

Not exactly "non contract" though is it!

I have a Megger that can do this. It beeps when in close proximity to a
high voltage. Not sure about the possibility of false positives, though
(inductive coupling) I must check it out one day when I can be arsed.



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This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

On Monday, 4 December 2017 00:10:01 UTC, John Rumm wrote:
On 03/12/2017 17:41, tabbypurr wrote:
On Sunday, 3 December 2017 17:31:31 UTC, wrote:

If this type is so unreliable what is the safest way to determine if a cable is safe to cut?

voltmeter

Not exactly "non contract" though is it!

No. Is that an issue?


NT

Hi John

That's a good point. When the power was on it had a more or less continuous beep. When the power was off the beep was more of a series of individual beeps. The thing that spooked me more was the self test seemingly not working.

Thanks

Lee.

Oh where to start on this one.
Most of these only have one connection, a bit like the old fashioned Neon
Screwdriver. I'd really like one that makes a sound myself of course.
However they seem to have no way to really detect the voltage that is there
that can harm you as against an induced voltage that can't. They normally
use you as if you were the other connection so really unless you can sink
some current on the line you are measuring if anywhere along the run it
picks up induced voltage from a live wire you get a false positive. In my
mind all wires really should have small bleed resistors on them to earth but
I guess over a whole city this would mean a significant power wastage.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
wrote in message
...
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before I cut
into it. It seems to detect voltage but when I switched the circuit off it
still seems to think there is voltage although the beep / led is not
continuous. I know the socket is off as I had something plugged into it
which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power button and
indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do the self
test thing. Brought a new one home to test on the off circuit and same
problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now thinking
maybe I am missing something?

Thanks

Lee.

Well, in my view, any voltage detector needs two connections Maybe a probe
on a piece of wire as well as the pen. Simply design a circuit which has a
small load in it, say a resistor and connect one end, say the probe to
neutral the other, say the pen to the possible live. You could work in one
of two ways, detect the voltage under load and or the current flow though
the load. An old Electrician had a wonderful thing made up with a little
pigmy low wattage bulb in a translucent box and a couple of probes. If the
light lit it was um, live. Only way to be sure he told me.
Brian

--
----- -
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please!
"Robin" wrote in message
...
On 03/12/2017 15:37, Bob Minchin wrote:
wrote:
Hi all

Just bought one of these

https://www.screwfix.com/p/lap-ms890...questid=287869

Reviews seemed good only needed it to confirm circuit is off before I
cut into it. It seems to detect voltage but when I switched the circuit
off it still seems to think there is voltage although the beep / led is
not continuous. I know the socket is off as I had something plugged into
it which then went off when I switched the circuit off.

The instructions say that it self tests when you press the power button
and indicates ok with a flashing LED. Mine gives a solid green.

Just took it back to Screwfix and tried 3 others and non seem to do the
self test thing. Brought a new one home to test on the off circuit and
same problems.

It seems unlikely that all 4 and dead (maybe a dodgy batch) but now
thinking maybe I am missing something?

Thanks

Lee.

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

--
Robin
reply-to address is (intended to be) valid

Brian Gaff wrote:

in my view, any voltage detector needs two connections

The whole point of a non-contact mains detector is that it has zero
connections.

Like any tool they're fallible, they can give false negatives (e.g. for
live SWA cable) and false positives (e.g. for a USB cable) but they're
better than using your tongue.

Some do have audible output.

On 04/12/2017 05:18, wrote:
On Monday, 4 December 2017 00:10:01 UTC, John Rumm wrote:
On 03/12/2017 17:41, tabbypurr wrote:
On Sunday, 3 December 2017 17:31:31 UTC, wrote:

If this type is so unreliable what is the safest way to determine if a cable is safe to cut?

voltmeter

Not exactly "non contract" though is it!

No. Is that an issue?

Yes! The whole purpose of the volt stick style detector is that it can
make an assessment without needing any direct contact to the circuit,
and so avoids all the risks associated with that.

Also keep in mind that a false positive reading is equally possible from
a high impedance volt meter.


--
Cheers,

John.

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

On 03/12/2017 23:08, wrote:
On Sunday, 3 December 2017 21:35:32 UTC, Robin wrote:
On 03/12/2017 18:06, tabbypurr wrote:
On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

it isn't, it's just false positives. Come back when you understand them.


I'd be more impressed by your confidence if you'd bothered to state what
you are taking to be the purpose of a volt stick.

to detect voltage?

(Note I never said I
approved the use of a volt stick to prove a conductor "dead". I do
continue to fail to see why you claim they are "always unsound in
principle" to identify a live conductor - eg when there are several
conductors in a conduit.)

you could always read up on how they work and why they give false negatives and false positives.

If you use them according to the instructions, you should not get false
negatives.


--
Cheers,

John.

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

On Sun, 3 Dec 2017 14:59:24 -0800 (PST), wrote:

On Sunday, 3 December 2017 18:31:47 UTC, mechanic wrote:
On Sun, 3 Dec 2017 10:06:59 -0800 (PST), tabbypurr wrote:

As for false positives, I take it you mean the way they will
detect voltages which are totally safe for human contact. On
the whole I prefer to see that not so much a false positive as
an indication of the need to check further.

it isn't, it's just false positives. Come back when you
understand them.

In this case it seems a question of what is positive and what is
negative - the presence of mains voltage as a result of the test
could be taken either way.

I see the idiot's back

Great contribution.

On 03/12/2017 23:08, wrote:
On Sunday, 3 December 2017 21:35:32 UTC, Robin wrote:
On 03/12/2017 18:06, tabbypurr wrote:
On Sunday, 3 December 2017 17:41:40 UTC, Robin wrote:
On 03/12/2017 17:28, tabbypurr wrote:

They use an unsound principle and cannot be relied on. Don't buy

I'd be interested to learn more about that.

they produce false positives and false negatives, relying on one is a hazard


I'm well aware of the possibility of a false negative with them (as with
any device I've ever used). But I don't see why that makes the
*principle* of capacitive voltage sensing unsound.

it makes the way that principle is always applied unsound.

As for false positives, I take it you mean the way they will detect
voltages which are totally safe for human contact. On the whole I
prefer to see that not so much a false positive as an indication of the
need to check further.

it isn't, it's just false positives. Come back when you understand them.


I'd be more impressed by your confidence if you'd bothered to state what
you are taking to be the purpose of a volt stick.

to detect voltage?

(Note I never said I
approved the use of a volt stick to prove a conductor "dead". I do
continue to fail to see why you claim they are "always unsound in
principle" to identify a live conductor - eg when there are several
conductors in a conduit.)

you could always read up on how they work and why they give false negatives and false positives.


And what's that got to do with the *principle* of capacitive voltage
sensing?

Do you understand that any volt meter is capable of giving a false
negative? With a good quality one used properly they will be very rare
indeed but not impossible.

--
Robin
reply-to address is (intended to be) valid

On 04/12/2017 09:30, Brian Gaff wrote:

Most of these only have one connection, a bit like the old fashioned Neon
Screwdriver. I'd really like one that makes a sound myself of course.
However they seem to have no way to really detect the voltage that is there
that can harm you as against an induced voltage that can't. They normally
use you as if you were the other connection

I don't know if they all use the same principle but some non-contact
voltsticks work by detecting a potential gradient in the space near the
conductor so don't rely on any leakage current through you to ground.

If a cable runs alongside other live cables then there could well be
enough induced voltage in the 'dead' cable to show a false positive.
This type of false indication can sometimes be cancelled by placing your
hand on the outer surface of the cable insulation.

--
Mike Clarke

John Rumm wrote:

If you use them according to the instructions,
you should not get false negatives.

I don't remember mine (Kewtech) warning about not detecting live SWA
cables, presume the Flexishield type cable will always give a negative too?