I am replacing a pendant light together with the light switch. I've
totally disconnected them from the mains wiring -- I basically have two
sets of three wires sticking out of the wall and out of the ceiling.

When I turn the power back on at the consumer unit, and use a mains
tester (screwdriver type) on the three wires sticking out of the
ceiling, all three are shown as LIVE.

This strikes me as very odd.

Is this necessarily indicative of a serious wiring problem somewhere?

Thanks
Alexei

Alexei wrote in message
.com...
I am replacing a pendant light together with the light switch. I've
totally disconnected them from the mains wiring -- I basically have two
sets of three wires sticking out of the wall and out of the ceiling.

When I turn the power back on at the consumer unit, and use a mains
tester (screwdriver type) on the three wires sticking out of the
ceiling, all three are shown as LIVE.

This strikes me as very odd.

Is this necessarily indicative of a serious wiring problem somewhere?

Thanks
Alexei


Neon type testers can give misleading results. To be certain if a wire is
live, connect one side of a (mains) light bulb to a known neutral and probe
the unknown wires with the other bulb connection.

Bob

On 2 Oct 2005 09:35:50 -0700, "Alexei"
scrawled:

I am replacing a pendant light together with the light switch. I've
totally disconnected them from the mains wiring -- I basically have two
sets of three wires sticking out of the wall and out of the ceiling.

When I turn the power back on at the consumer unit, and use a mains
tester (screwdriver type) on the three wires sticking out of the
ceiling, all three are shown as LIVE.

That's because the neon screwdriver method of testing is absolutely
useless. It goes in the usefulness file along with cheap stud and pipe
detectors.

This strikes me as very odd.

Nah, quite normal. It'll probably tell you your elbows live but fail
to tell you a live cable is live.

Is this necessarily indicative of a serious wiring problem somewhere?

Serious lack of professionalism tbh. Get a proper tester on the job.
--
Stuart @ SJW Electrical

Please Reply to group

This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?

I'll do the lightbulb test some other day, when there's sufficient
daylight.

On 2 Oct 2005 10:29:33 -0700,it is alleged that "Alexei"
spake thusly in uk.d-i-y:

This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?

If one or more of the cables that are disconnected is running parallel
to a live cable. If it's not actually a neon screwdriver but one of
the 'continuity testing and mains testing' Hypersensitive LED ones I
noticed B&Q have on clearance, the value of 'running parallel to'
changes to 'within spitting distance of'.


I'll do the lightbulb test some other day, when there's sufficient
daylight.


--
There is no reason anyone would want a computer in their home.
- Ken Olson, President of DEC, 1977

On 2 Oct 2005 10:29:33 -0700, "Alexei"
scrawled:

Out of interest, under what
circumstances could a neon-type tester give misleading results?

Whenever you use it.

I'll do the lightbulb test some other day, when there's sufficient
daylight.

If you're planning on doing any more electrical work it would be
worthwhile investing in a reasonable multimeter. You can pick up
something respectable from around £20.
--
Stuart @ SJW Electrical

Please Reply to group

Here a full account of what I've been trying to do.

I am installing a new pendant light. To this end, I've disconnected the
existing (working) light, and wired the new light, connecting red to
brown, black to blue and the third wire to both green/yellow and the
mounting bracket (the pendant is mostly metal).

This seemed to work perfectly. I've left the light on for about 15
minutes, after which the switch at the consumer unit tripped. I've
checked the bulbs, suspecting one might have blown, but all appeared
OK. I've turned the trip switch back on, but the light wouldn't work.

I suspected the dimmer switch may have been to blame. I disconnected it
to take a look and it looked dead (evidence of smoke).

I replaced the switch with a 450W-rated dimmer (the load is 5x60W, the
old dimmer was rated for 400W), wiring black to C and red to L1. The
new one died exactly the same death the moment I tried to turn it on.

At this point I've removed both the light and the switch to see if I've
managed to screw something up, but everything looks OK as far as wiring
goes: all the wires are connected where I intended them to be
connected, there is no exposed wiring, etc.

Messing about with the tester was just a quick sanity check; I didn't
realise they are unreliable. Stuart's comment about lack of
professionalism is a fair one; however, it is worth bearing in mind
that this is a DIY forum and I felt perfectly up to this relatively
straightforward job.

I am probably going to get a qualified electrician to sort this out. In
the meantime I would be most interested to hear what steps you would
take if you were trying to figure this out.

Thanks
Alexei

On 2 Oct 2005 11:17:36 -0700,it is alleged that "Alexei"
spake thusly in uk.d-i-y:

Here a full account of what I've been trying to do.

I am installing a new pendant light. To this end, I've disconnected the
existing (working) light, and wired the new light, connecting red to
brown, black to blue and the third wire to both green/yellow and the
mounting bracket (the pendant is mostly metal).

This seemed to work perfectly. I've left the light on for about 15
minutes, after which the switch at the consumer unit tripped. I've
checked the bulbs, suspecting one might have blown, but all appeared
OK. I've turned the trip switch back on, but the light wouldn't work.

I suspected the dimmer switch may have been to blame. I disconnected it
to take a look and it looked dead (evidence of smoke).

I replaced the switch with a 450W-rated dimmer (the load is 5x60W, the
old dimmer was rated for 400W), wiring black to C and red to L1. The
new one died exactly the same death the moment I tried to turn it on.

At this point I've removed both the light and the switch to see if I've
managed to screw something up, but everything looks OK as far as wiring
goes: all the wires are connected where I intended them to be
connected, there is no exposed wiring, etc.

Messing about with the tester was just a quick sanity check; I didn't
realise they are unreliable. Stuart's comment about lack of
professionalism is a fair one; however, it is worth bearing in mind
that this is a DIY forum and I felt perfectly up to this relatively
straightforward job.

I am probably going to get a qualified electrician to sort this out. In
the meantime I would be most interested to hear what steps you would
take if you were trying to figure this out.

Thanks
Alexei

In your original post, you stated you had "two sets of three wires
sticking out of the wall and out of the ceiling."

Just to clarify, did you mean 'one set of 3 at the switch, and one set
of 3 at the lighting point' ?

If so, it sounds like you're connecting things up right, (although the
black at the switch should technically be sleeved red or brown).

If the fault is occurring with this apparently perfectly normal
wiring, you have 2 choices.

1) Call an electrician (guaranteed but pricy).

2) Try swapping parts, obtain a 'normal' lampholder and 60w lamp, and
a light switch of the 99p variety, and see if the fault recurs when
you swap them in. If it doesn't, the fault was in one of the 2 things
you just eliminated.

It sounds to me like one of 3 possibilities.

A) The new dimmer was faulty. (unlikely as a second also died the same
way)

B) The new light fixture is faulty (possibly caused during
manufacture)

C) The junction box (which must be present somewhere, probably above
the ceiling) has an intermittent short circuit, this should be
considered when trying 'turn it on and see' methods, not trying to
induce paranoia, but a slow smouldering fire under the floor is A Bad
Thing.

--
There is no reason anyone would want a computer in their home.
- Ken Olson, President of DEC, 1977

In an earlier contribution to this discussion,
Alexei wrote:

Here a full account of what I've been trying to do.

I am installing a new pendant light. To this end, I've disconnected
the existing (working) light, and wired the new light, connecting red
to brown, black to blue and the third wire to both green/yellow and
the mounting bracket (the pendant is mostly metal).

This seemed to work perfectly. I've left the light on for about 15
minutes, after which the switch at the consumer unit tripped. I've
checked the bulbs, suspecting one might have blown, but all appeared
OK. I've turned the trip switch back on, but the light wouldn't work.

I suspected the dimmer switch may have been to blame. I disconnected
it to take a look and it looked dead (evidence of smoke).

I replaced the switch with a 450W-rated dimmer (the load is 5x60W, the
old dimmer was rated for 400W), wiring black to C and red to L1. The
new one died exactly the same death the moment I tried to turn it on.

At this point I've removed both the light and the switch to see if
I've managed to screw something up, but everything looks OK as far as
wiring goes: all the wires are connected where I intended them to be
connected, there is no exposed wiring, etc.

Messing about with the tester was just a quick sanity check; I didn't
realise they are unreliable. Stuart's comment about lack of
professionalism is a fair one; however, it is worth bearing in mind
that this is a DIY forum and I felt perfectly up to this relatively
straightforward job.

I am probably going to get a qualified electrician to sort this out.
In the meantime I would be most interested to hear what steps you
would take if you were trying to figure this out.

Thanks
Alexei

A neon tester can pick up induced voltages in wires which run parallel to
live wires, and which are *not* actually live. Far better to use a
voltmeter - or a multi-meter set to an appropriate scale for measuring 240v
AC.

It's possible that your dimmer switches don't like the type of load you're
giving them even though, in theory, they have more than enough capacity.
have you checked what happens when you use a bog standard on-off switch
rather than a dimmer? It's easier to get it working with an ordinary switch
first, and then worry about dimming, later.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On 2 Oct 2005 11:17:36 -0700, "Alexei"
scrawled:

Stuart's comment about lack of
professionalism is a fair one; however, it is worth bearing in mind
that this is a DIY forum and I felt perfectly up to this relatively
straightforward job.

Well, evidently it's not straight forward enough.

Sounds like you've pulled down the old pendant, blatantly ignored the
loop in and switch wire connections and wired the light across the
live and neutral, in parallel with the dimmer switch, causing the
light to work and the switch to explode.

When you wired it up did the switch work and the light dim up and down
as it should?

I am probably going to get a qualified electrician to sort this out. In
the meantime I would be most interested to hear what steps you would
take if you were trying to figure this out.

I would get my test meter out so we're stuffed at this point as you
haven't got one!
--
Stuart @ SJW Electrical

Please Reply to group

If you're planning on doing any more electrical work it would be
worthwhile investing in a reasonable multimeter. You can pick up
something respectable from around =A320.

What would you be looking for in a multimeter for this type of work?

I use one of those for non-mains work:
http://www.maplin.co.uk/Module.aspx?...411&doy=3D2m10

However, I am not entirely sure whether it would be appropriate (or
even safe) to take it near the mains.

Alexei

Sounds like you've pulled down the old pendant, blatantly ignored the
loop in and switch wire connections and wired the light across the
live and neutral, in parallel with the dimmer switch, causing the
light to work and the switch to explode.

When you wired it up did the switch work and the light dim up and down
as it should?

Yes, everything worked as it should. The lights turned on and off and
dimmed up and down as expected.

Alexei

On 2 Oct 2005 12:00:34 -0700, "Alexei"
scrawled:

If you're planning on doing any more electrical work it would be
worthwhile investing in a reasonable multimeter. You can pick up
something respectable from around £20.

What would you be looking for in a multimeter for this type of work?

I use one of those for non-mains work:
http://www.maplin.co.uk/Module.aspx?...25411&doy=2m10

However, I am not entirely sure whether it would be appropriate (or
even safe) to take it near the mains.

No, me neither.

I've used AlphaTek for some good cheap meters in the past. Robin also
do an autoranging rugged DMM for £20 odd (I think, I could be making
that bit about Robin up).

As a side note, it's a pity Maplin can't spell 'professional' (as in
proffessional multimeter, down on the left).
--
Stuart @ SJW Electrical

Please Reply to group

A neon tester can pick up induced voltages in wires which run parallel to
live wires, and which are *not* actually live. Far better to use a
voltmeter - or a multi-meter set to an appropriate scale for measuring 240v
AC.

Is it fair to say that this type of tester can give false positive but
not false negatives (i.e. if a wire is live, a working tester will
always show it as live)? This is purely hypothetically of course, I am
not going to rely on one from now on. :-)

It's possible that your dimmer switches don't like the type of load you're
giving them even though, in theory, they have more than enough capacity.
have you checked what happens when you use a bog standard on-off switch
rather than a dimmer? It's easier to get it working with an ordinary switch
first, and then worry about dimming, later.

No, I've not checked that yet, but am intending to. The reason I've not
tried this earlier is that I wasn't expecting the second dimmer to
explode in an apparently working setup. Otherwise the second switch
would have been an ordinary one.

Alexei

Chip,

Thanks for the detailed reply.

Just to clarify, did you mean 'one set of 3 at the switch, and one set
of 3 at the lighting point' ?

That's right.

Swapping parts sounds like a good plan. I've got all the parts I need,
and will probably have another stab at this before calling an
electrician.

A) The new dimmer was faulty. (unlikely as a second also died the same
way)

As suggested, I'll try a normal switch.

B) The new light fixture is faulty (possibly caused during manufacture)

I have the old pendant (basically a lightbulb-on-a-flex type thing),
which I can try. FWIW, I've used an ohmmeter to measure the
resistance across the wires on the new fixture, and there's no evidence
of any short-circuits (by no means a definitive test).

C) The junction box (which must be present somewhere, probably above
the ceiling) has an intermittent short circuit, this should be
considered when trying 'turn it on and see' methods, not trying to
induce paranoia, but a slow smouldering fire under the floor is A Bad
Thing.

That's a scary thought. I take comfort in knowing that everything
worked fine until I started messing around with it, and the room got
completely rewired about 4 months ago.

Alexei

On 2 Oct 2005 12:13:47 -0700, "Alexei"
scrawled:

Is it fair to say that this type of tester can give false positive but
not false negatives (i.e. if a wire is live, a working tester will
always show it as live)? This is purely hypothetically of course, I am
not going to rely on one from now on. :-)

I wouldn't rely on a neon tester to give a true anything. I think the
term "working tester" when used in the sense of a neon screwdriver is
stretching the truth somewhat.
--
Stuart @ SJW Electrical

Please Reply to group

On 2 Oct 2005 12:07:39 -0700, "Alexei"
scrawled:

Sounds like you've pulled down the old pendant, blatantly ignored the
loop in and switch wire connections and wired the light across the
live and neutral, in parallel with the dimmer switch, causing the
light to work and the switch to explode.

When you wired it up did the switch work and the light dim up and down
as it should?

Yes, everything worked as it should. The lights turned on and off and
dimmed up and down as expected.

Hmmm, were any other lights on the circuit switched on at the same
time? Did any of them display strange behaviour whilst the testing of
this one was going on?
--
Stuart @ SJW Electrical

Please Reply to group

On 2 Oct 2005 12:25:13 -0700,it is alleged that "Alexei"
spake thusly in uk.d-i-y:

[snip]

C) The junction box (which must be present somewhere, probably above
the ceiling) has an intermittent short circuit, this should be
considered when trying 'turn it on and see' methods, not trying to
induce paranoia, but a slow smouldering fire under the floor is A Bad
Thing.

That's a scary thought. I take comfort in knowing that everything
worked fine until I started messing around with it, and the room got
completely rewired about 4 months ago.

Hmm, being fairly new, I wonder if a connection could be loose and
arcing, which arcs can then spread to earth or neutral tripping the
breaker?

The multimeter advice you have got from other respondents is certainly
a good idea too.

--
There is no reason anyone would want a computer in their home.
- Ken Olson, President of DEC, 1977

In message .com,
Alexei writes
This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?

Almost any - chuck it away and buy a meter


I'll do the lightbulb test some other day, when there's sufficient
daylight.


--
geoff

Stuart wrote:
I would get my test meter out so we're stuffed at this point as you
haven't got one!

Since I am treating this as a learning experience, I would appreciate
if you could outline initial tests that you would do with your meter if
you were in this situation.

Thanks
Alexei

Hmmm, were any other lights on the circuit switched on at the same
time? Did any of them display strange behaviour whilst the testing of
this one was going on?

There are no other lights on that circuit.

Alexei

There is one more detail that just came back to me.

When I was removing the old dimmer, I am pretty certain that the three
wires (red, black and uninsulated) were wired to the three terminals on
the switch (C, L1, L2 - it was a 2-way switch used as 1-way).

This is not a setup I've encountered before. Have you seen a setup like
this? Is it even standard?

In retrospect, I should have noticed the unfamiliar wiring, and at
least noted it down...

Alexei

In an earlier contribution to this discussion,
Alexei wrote:

If you're planning on doing any more electrical work it would be
worthwhile investing in a reasonable multimeter. You can pick up
something respectable from around £20.

What would you be looking for in a multimeter for this type of work?

I use one of those for non-mains work:
http://www.maplin.co.uk/Module.aspx?...25411&doy=2m10

However, I am not entirely sure whether it would be appropriate (or
even safe) to take it near the mains.

Alexei

If you click on 'Spec' in the above reference, it gives you the ranges
covered - one of which is 600v AC - so it's obviously designed to cope with
mains.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

On 2 Oct 2005 13:26:37 -0700,it is alleged that "Alexei"
spake thusly in uk.d-i-y:

There is one more detail that just came back to me.

When I was removing the old dimmer, I am pretty certain that the three
wires (red, black and uninsulated) were wired to the three terminals on
the switch (C, L1, L2 - it was a 2-way switch used as 1-way).

This is not a setup I've encountered before. Have you seen a setup like
this? Is it even standard?

Absolutely not, at this point, I am going to say 'call an electrician,
and NOT the one who did this'

In retrospect, I should have noticed the unfamiliar wiring, and at
least noted it down...

Alexei


--
There is no reason anyone would want a computer in their home.
- Ken Olson, President of DEC, 1977

In an earlier contribution to this discussion,
Alexei wrote:


Is it fair to say that this type of tester can give false positive but
not false negatives (i.e. if a wire is live, a working tester will
always show it as live)?

Not necessarily! I have one which seems to have gone on the blink in the
middle of a job the other day. At the start of the job it was lighting up on
live wires - and a bit later, it wasn't! It was only when I got my meter on
the job that I discovered that the right wires *were* live after all.
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

If you click on 'Spec' in the above reference, it gives you the ranges
covered - one of which is 600v AC - so it's obviously designed to cope with
mains.

Pardon my ignorance, but is this a sufficient indication that it's
designed to cope with currents found in mains circuits?

Alexei

Not necessarily! I have one which seems to have gone on the blink in the
middle of a job the other day. At the start of the job it was lighting up on
live wires - and a bit later, it wasn't! It was only when I got my meter on
the job that I discovered that the right wires *were* live after all.

Ouch! Mine is going into the bin (got enough screwdrivers as it is).

Alexei

On 2 Oct 2005 13:13:18 -0700, "Alexei"
scrawled:

Stuart wrote:
I would get my test meter out so we're stuffed at this point as you
haven't got one!

Since I am treating this as a learning experience, I would appreciate
if you could outline initial tests that you would do with your meter if
you were in this situation.

So you want to me to tell you what I would do, bearing in mind that if
I was at your house doing it you would be paying for all the years of
experience that have gone into acquiring this!

First thing would be to check the wiring, I'm not convinced you've
connected it up properly. I'd remove all wiring from the light point,
seperate and turn on power to test on the AC range which is the feed.
Next, with power back off, onto continuity and make sure the switch
wire really is the switch wire and I might even do a IR test on them.
I don't think there are any junction boxes opn this by the sounds of
it so we shouldn't need floors up or ceilings down.

Did the dimmer work the right way round, i.e. clockwise = brighter?
Did you connect up all the wires in the light fitting in parrallel,
i.e. all both reds to brown, both blacks to blue?
--
Stuart @ SJW Electrical

Please Reply to group

On 2 Oct 2005 13:26:37 -0700, "Alexei"
scrawled:

There is one more detail that just came back to me.

Hang on then, here we go!

When I was removing the old dimmer, I am pretty certain that the three
wires (red, black and uninsulated) were wired to the three terminals on
the switch (C, L1, L2 - it was a 2-way switch used as 1-way).

Something not right there. Sounds like a muppet fitted it, or it
appeared to be connected like that but in actual fact wasn't. Was it a
brass dimmer, was the uninsulated (which should be sheathed with
green\yellow sleeving, actually connected to an earth terminal on the
plate?

This is not a setup I've encountered before. Have you seen a setup like
this? Is it even standard?

No, if it was as you say it was non-compliant and wrong, and possibly
dangerous.

In retrospect, I should have noticed the unfamiliar wiring, and at
least noted it down...

Might have been an idea. Next time, utilise the functions of the
digital camera first
--
Stuart @ SJW Electrical

Please Reply to group

On Sun, 02 Oct 2005 20:00:08 GMT, raden wrote:

In message .com,
Alexei writes
This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?

Almost any - chuck it away and buy a meter

Actually an "electronics"-type meter can be just as misleading as a
neon screwdriver. If it has a very high input impedance it won't load
the circuit under test - just like a neon.
A much better bet would be a meter with much lower ohms-per-volt.

--
Frank Erskine

Thanks for sharing this. It looks likely that I will end up getting
professional help anyhow, but it doesn't mean I can't learn from the
experience.

To answer your questions:
Did the dimmer work the right way round, i.e. clockwise = brighter?

Yes it did. While I was testing it, I observed no anomalies whatsoever.

Did you connect up all the wires in the light fitting in parrallel,
i.e. all both reds to brown, both blacks to blue?

There is only one set of wires at the ceiling rose, so there is nothing
to connect in parallel.

Alexei

When I was removing the old dimmer, I am pretty certain that the three
wires (red, black and uninsulated) were wired to the three terminals on
the switch (C, L1, L2 - it was a 2-way switch used as 1-way).

Something not right there. Sounds like a muppet fitted it, or it
appeared to be connected like that but in actual fact wasn't. Was it a
brass dimmer, was the uninsulated (which should be sheathed with
green\yellow sleeving, actually connected to an earth terminal on the
plate?

No, the dimmer was a plastic one fitted onto a metal backbox. I am
pretty sure none of the three wires were connected to the terminal on
the backbox.

However, it is not impossible that my memory is wrong.

Alexei

Actually an "electronics"-type meter can be just as misleading as a
neon screwdriver. If it has a very high input impedance it won't load
the circuit under test - just like a neon.
A much better bet would be a meter with much lower ohms-per-volt.

The one I have has input impedance of 1MOhm, which certainly appears
high.

Could anyone recommend any specific models of multimeters that would be
suitable for this type of work, as well as good vendors (online or
otherwise)? Something around =A320-=A330 mark would be good.

Thanks
Alexei

In an earlier contribution to this discussion,
Alexei wrote:

If you click on 'Spec' in the above reference, it gives you the
ranges covered - one of which is 600v AC - so it's obviously
designed to cope with mains.

Pardon my ignorance, but is this a sufficient indication that it's
designed to cope with currents found in mains circuits?

Alexei

You're not measuring *current* - you're measuring *voltage*! You do know the
difference?
--
Cheers,
Set Square
______
Please reply to newsgroup. Reply address is invalid.

Have you connected all the reds together and all the blacks together at the
ceiling rose? If so the dimmer will be connected across the mains and not in
series with the light

Thanks for the reply. There is only one set of wires at the ceiling
rose, which I have wired to the fixture (black to blue, red to brown
and uninsulated to green/yellow).

Alexei

Alexei wrote:
Chip,

Thanks for the detailed reply.

Just to clarify, did you mean 'one set of 3 at the switch, and one
set of 3 at the lighting point' ?

That's right.


So where's your live feed?
There should be 2 sets of wires at the ceiling rose i.e a feed and a
switch wire.
--
Sir Benjamin Middlethwaite

So where's your live feed?
There should be 2 sets of wires at the ceiling rose i.e a feed and a switch wire.

I've not done the wiring myself, so I don't know for sure. However, the
fact that there is only one set of wires at the lighting point suggests
that this may be a junction-box system (no idea where the junction box
is though).

Alexei

On 2 Oct 2005 09:35:50 -0700, "Alexei" wrote:

| I am replacing a pendant light together with the light switch. I've
| totally disconnected them from the mains wiring -- I basically have two
| sets of three wires sticking out of the wall and out of the ceiling.
|
| When I turn the power back on at the consumer unit, and use a mains
| tester (screwdriver type) on the three wires sticking out of the
| ceiling, all three are shown as LIVE.
|
| This strikes me as very odd.
|
| Is this necessarily indicative of a serious wiring problem somewhere?

Get a domestic multimeter Maplins sell them for GBP3 in the stores.

--
Dave Fawthrop dave hyphenologist co uk
The London suicide bombers killed innocent commuters.
Animal rights terrorists and activists kill innocent patients.

Alexei wrote:

This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?


capacitative coupling to any mains source.

E,G, a bit of T&E lying next to a live cable will show 'hot' on all its
wires.


Its a useful feature or a curse depending.

I'll do the lightbulb test some other day, when there's sufficient
daylight.

On Sun, 02 Oct 2005 23:18:00 +0100, wrote:

On 2 Oct,
Frank Erskine wrote:

On Sun, 02 Oct 2005 20:00:08 GMT, raden wrote:

In message .com,
Alexei writes
This would explain it, thanks. Out of interest, under what
circumstances could a neon-type tester give misleading results?

Almost any - chuck it away and buy a meter

Actually an "electronics"-type meter can be just as misleading as a
neon screwdriver. If it has a very high input impedance it won't load
the circuit under test - just like a neon.
A much better bet would be a meter with much lower ohms-per-volt.

Very relevant, a digital multimeter may have an input impedance of several
megohms, more than that of a neon screwdriver.

An AVO (model40) or similar, verified before and after use is a much better
test.

ISTR that AVO used to do their model 7 in either an "electrical" or an
"electronics" version. The electrical one was only about 200 or 500
ohms/volt, which had the above advantage as well as being much more
rugged and capable of withstanding say being dropped from a pair of
steps :-)

--
Frank Erskine