Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it. The
lights are operated via a rocker switch at the top rh *side covered in
a rubber membrane. The whole thing is shiny mirror like metal finish
inside and out. I have an isolator switch mounted on the wall in the
room behind it. It's above a wash hand basin in my downstairs shower
room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I get
a small electrical shock, on the back of my arm, just below my elbow,
where it touches the corner of the open door! It's a constant 'buzz' -
not painful, but uncomfortable and obviously worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of Years
and only when the missus mentioned getting the same shock have I
thought I'd better get it resolved

deano wrote:
Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it. The
lights are operated via a rocker switch at the top rh side covered in
a rubber membrane. The whole thing is shiny mirror like metal finish
inside and out. I have an isolator switch mounted on the wall in the
room behind it. It's above a wash hand basin in my downstairs shower
room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I get
a small electrical shock, on the back of my arm, just below my elbow,
where it touches the corner of the open door! It's a constant 'buzz' -
not painful, but uncomfortable and obviously worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of Years
and only when the missus mentioned getting the same shock have I
thought I'd better get it resolved

I'll leave the electricians in the group to answer your query - but on the
issue of the 'buzz'... When my wife's iPod is on charge (using a non-Apple
compatible charger), if you pick it up and run your finger lightly over the
metal surface, there is also this 'buzz' sensation. I wouldn't describe it
as an electric shock - just a very very mild 'tingling' sensation.

As the output of the charger is low, I am assuming that there is no danger
from this...

--
Kev

Yep... 'A mild tingling sensation' also is a
better way of describing what I'm getting.

Btw: using google groups on my iPhone is very
Frustrating- is there an app available that would
make using this ng any easier?
Anyone?

On May 12, 9:49*am, deano wrote:
Yep... 'A mild tingling sensation' also is a
better way of describing what I'm getting.

Btw: using google groups on my iPhone is very
Frustrating- is there an app available that would
make using this ng any easier?
Anyone?

Equipotential bonding would solve it. I cant comment on the risk of
the situation, as I dont know if its filter capacitive leakage or
cable damage. One's harmless, one liable to be fatal.


NT

Tabby wrote:

On May 12, 9:49 am, deano wrote:
Yep... 'A mild tingling sensation' also is a
better way of describing what I'm getting.

Btw: using google groups on my iPhone is very
Frustrating- is there an app available that would
make using this ng any easier?
Anyone?

Equipotential bonding would solve it. I cant comment on the risk of
the situation, as I dont know if its filter capacitive leakage or
cable damage. One's harmless, one liable to be fatal.


NT

Exactly.

We don't know what's causing the problem, but there is a chance it could be
something that could fail into becoming extremely dangerous.

Risk assessment mental exercise:

1) Dangerous condition not proven but suspected: outcome potentially
devastating

2) Inconvenience of isolating suspect circuit - sod all.

Makes it a no brainer - turn it off and check it out.

--
Tim Watts

On May 12, 10:57*am, Tim Watts wrote:
Tabby wrote:
On May 12, 9:49 am, deano wrote:
Yep... 'A mild tingling sensation' also is a
better way of describing what I'm getting.

Btw: using google groups on my iPhone is very
Frustrating- is there an app available that would
make using this ng any easier?
Anyone?

Equipotential bonding would solve it. I cant comment on the risk of
the situation, as I dont know if its filter capacitive leakage or
cable damage. One's harmless, one liable to be fatal.

NT

Exactly.

We don't know what's causing the problem, but there is a chance it could be
something that could fail into becoming extremely dangerous.

Risk assessment mental exercise:

1) Dangerous condition not proven but suspected: outcome potentially
devastating

2) Inconvenience of isolating suspect circuit - sod all.

Makes it a no brainer - turn it off and check it out.

deano wrote
It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall?

which means we know its not capacitors in the power supply, making the
likelihood of a potentially fatal fault fairly high.


NT

"deano" wrote in message
...
Yep... 'A mild tingling sensation' also is a
better way of describing what I'm getting.

Btw: using google groups on my iPhone is very
Frustrating- is there an app available that would
make using this ng any easier?
Anyone?

Google shows a lot of hits.

E.G. http://mac.softpedia.com/get/iPhone-...ewsGroup.shtml

I have no idea what they are like as I don't have, or want, an iPhony.

On 12/05/2011 10:53, dennis@home wrote:

Google shows a lot of hits.

Most unlikely to have anything to do with Usenet. The term 'NewsReader'
is mostly associated with RSS these days.

E.G. http://mac.softpedia.com/get/iPhone-...ewsGroup.shtml


NewsTap (Usenet Newsreader) is in the iTunes App Store.

http://mobile.clauss-net.de/NewsTap/

In iTunes - Beware,

"You must be at least 17 years old to download this application"

* Infrequent/Mild Sexual Content or Nudity
* Infrequent/Mild Cartoon or Fantasy Violence
* Infrequent/Mild Simulated Gambling
* Infrequent/Mild Profanity or Crude Humour
* Infrequent/Mild Horror/Fear Themes
* Frequent/Intense Mature/Suggestive Themes
* Infrequent/Mild Alcohol, Tobacco, Drug Use or References to these"

Must be good then....

:-)

--
Adrian C

On 12/05/2011 09:04, Ret. wrote:

[...] When my wife's iPod is on charge (using a non-Apple compatible
charger), if you pick it up and run your finger lightly over the
metal surface, there is also this 'buzz' sensation. I wouldn't
describe it as an electric shock - just a very very mild 'tingling'
sensation.

These 'tingles' are usually the result of capacitive leakage between the
mains and the case of a Class 2 ('double insulated') appliance. The
relevant safety standards usually allow up to to 0.5 mA leakage at 50 Hz
(more at higher frequencies). It's completely harmless[*] but can be
annoying and/or worrying. (The 'return' path for the current is via the
body's natural capacitance to earth, typically a few hundred
picofarads.) It's becoming more common with the move away from
iron-cored transformers to switch-mode circuits in wall-wart PSUs - a
consequence of the WEEE and EuP directives.

With a high impedance voltmeter (any DMM these days) you'll typically
measure 100 volts or more between the case and earth. The source
impedance of these errant volts is very high though, and just touching
the case will lower the touch voltage considerably. Temporarily earth
the case via (say) a 10k ohm resistor and measure the voltage across the
resistor if you want to get an idea of the available touch current.

As the output of the charger is low, I am assuming that there is no
danger from this...

Unless there is a fault, no.
[*] One case to be aware of is where several items of Class 2 AV
equipment are interconnected by the signal wiring. Here the available
leakage touch current will add up and can reach dangerous levels (3.5
mA is considered dangerous, 10-15 mA can be lethal). Earthing the
system (either directly or via a resistor) is advised in such cases.

--
Andy

Andy Wade wrote:
On 12/05/2011 09:04, Ret. wrote:

[...] When my wife's iPod is on charge (using a non-Apple compatible
charger), if you pick it up and run your finger lightly over the
metal surface, there is also this 'buzz' sensation. I wouldn't
describe it as an electric shock - just a very very mild 'tingling'
sensation.

These 'tingles' are usually the result of capacitive leakage between
the mains and the case of a Class 2 ('double insulated') appliance.
The relevant safety standards usually allow up to to 0.5 mA leakage
at 50 Hz (more at higher frequencies). It's completely harmless[*]
but can be annoying and/or worrying. (The 'return' path for the
current is via the body's natural capacitance to earth, typically a
few hundred picofarads.) It's becoming more common with the move
away from iron-cored transformers to switch-mode circuits in
wall-wart PSUs - a consequence of the WEEE and EuP directives.

With a high impedance voltmeter (any DMM these days) you'll typically
measure 100 volts or more between the case and earth. The source
impedance of these errant volts is very high though, and just touching
the case will lower the touch voltage considerably. Temporarily earth
the case via (say) a 10k ohm resistor and measure the voltage across
the resistor if you want to get an idea of the available touch
current.

As the output of the charger is low, I am assuming that there is no
danger from this...

Unless there is a fault, no.

[*] One case to be aware of is where several items of Class 2 AV
equipment are interconnected by the signal wiring. Here the available
leakage touch current will add up and can reach dangerous levels (3.5
mA is considered dangerous, 10-15 mA can be lethal). Earthing the
system (either directly or via a resistor) is advised in such cases.

Thanks for that.

--
Kev

Ret. wrote:

deano wrote:
Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it. The
lights are operated via a rocker switch at the top rh side covered in
a rubber membrane. The whole thing is shiny mirror like metal finish
inside and out. I have an isolator switch mounted on the wall in the
room behind it. It's above a wash hand basin in my downstairs shower
room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I get
a small electrical shock, on the back of my arm, just below my elbow,
where it touches the corner of the open door! It's a constant 'buzz' -
not painful, but uncomfortable and obviously worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of Years
and only when the missus mentioned getting the same shock have I
thought I'd better get it resolved

I'll leave the electricians in the group to answer your query - but on the
issue of the 'buzz'... When my wife's iPod is on charge (using a
non-Apple compatible charger), if you pick it up and run your finger
lightly over the metal surface, there is also this 'buzz' sensation. I
wouldn't describe it as an electric shock - just a very very mild
'tingling' sensation.

As the output of the charger is low, I am assuming that there is no danger
from this...


I would stop using that charger right now!

At least get it tested. There should not be enough leakage to cause any
"buzz" sensation, which is clearly mains leakage and not a static shock.

You have to ask yourself, "what if the leakage path in the device worsens,
suddenly, due to component breakdown". The fraction of a mA or so you are
feeling could suddenly become several 10's of mA which is borderline lethal
depending on circumstances, constitution.

To the OP - same applies. Isolate the lights and get it checked.

--
Tim Watts

Tim Watts wrote:
Ret. wrote:

deano wrote:
Its a metal (stainless steel) casing with a mirror door, has a
canopy over the door with 2 low voltage downlighters recessed into
it. The lights are operated via a rocker switch at the top rh side
covered in a rubber membrane. The whole thing is shiny mirror like
metal finish inside and out. I have an isolator switch mounted on
the wall in the room behind it. It's above a wash hand basin in my
downstairs shower room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I
get a small electrical shock, on the back of my arm, just below my
elbow, where it touches the corner of the open door! It's a
constant 'buzz' - not painful, but uncomfortable and obviously
worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of
Years and only when the missus mentioned getting the same shock
have I thought I'd better get it resolved

I'll leave the electricians in the group to answer your query - but
on the issue of the 'buzz'... When my wife's iPod is on charge
(using a non-Apple compatible charger), if you pick it up and run
your finger lightly over the metal surface, there is also this
'buzz' sensation. I wouldn't describe it as an electric shock - just
a very very mild 'tingling' sensation.

As the output of the charger is low, I am assuming that there is no
danger from this...


I would stop using that charger right now!

At least get it tested. There should not be enough leakage to cause
any "buzz" sensation, which is clearly mains leakage and not a static
shock.

You have to ask yourself, "what if the leakage path in the device
worsens, suddenly, due to component breakdown". The fraction of a mA
or so you are feeling could suddenly become several 10's of mA which
is borderline lethal depending on circumstances, constitution.

To the OP - same applies. Isolate the lights and get it checked.

In fact, we haven't had to use the 'compatible' charger for a couple of
months because I bought my wife an iPad and that came with an Apple charger
that also charges her iPod.

I kept the compatible charger as a 'spare' but, in view of what you say,
I'll consign it to the bin.

--
Kev

Ret. wrote:


In fact, we haven't had to use the 'compatible' charger for a couple of
months because I bought my wife an iPad and that came with an Apple
charger that also charges her iPod.

I kept the compatible charger as a 'spare' but, in view of what you say,
I'll consign it to the bin.


Wise, for the small amount they cost.

If it were me, I'd stick my Megger across it (ie short all the inputs, short
all the outputs then across the pair) on the 500V setting. If it survived
that with a high enough reading (say at least 10Megohms) , I'd be happy
again.

--
Tim Watts

On Thu, 12 May 2011 00:26:55 -0700 (PDT), deano
wrote:

How can I go about finding the fault?
Depends what test equipment you have (DMM, Avo etc)?
You really do not want to be using a wet finger to fault-find.

It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall?

Does the wiring from the isolator to the transformer (assumed in the
cabinet somewhere) include an earth wire?
If so, is it connected to the metalwork? Continuity?
I would have expected the isolator (FCU?) to disconnect the line from
the transformer so there should be no leakage possible.

On 12/05/2011 10:10, Geo wrote:

Does the wiring from the isolator to the transformer (assumed in the
cabinet somewhere) include an earth wire?
If so, is it connected to the metalwork?

If the cabinet is a Class 2 appliance it shouldn't be earthed to the CPC
of the wiring. The CPC should be terminated, but not connected to
anything. Local supplementary bonding could be used to kill the tingle
though, if desired.

If it's Class 1 and in the Zones it should be earthed and bonded (unless
the 17th ed. bathroom bonding exemption is being used). However any
tingle from a Class 1 appliance should be investigated as it tends to
suggest that the earthing has come adrift.

I would have expected the isolator (FCU?) to disconnect the line from
the transformer so there should be no leakage possible.

Yes, that's the worrying bit here. The 'problem' should completely stop
when the isolator is open. Cable damage within the wall before the
isolator could be indicated. Definitely "requires investigation," I think.

--
Andy

On May 12, 8:26*am, deano wrote:
Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it. The
lights are operated via a rocker switch at the top rh *side covered in
a rubber membrane. The whole thing is shiny mirror like metal finish
inside and out. I have an isolator switch mounted on the wall in the
room behind it. It's above a wash hand basin in my downstairs shower
room- where I shave.

With the door open, as I put my hand in to get my shaving foam, I get
a small electrical shock, on the back of my arm, just below my elbow,
where it touches the corner of the open door! It's a constant 'buzz' -
not painful, but uncomfortable and obviously worrying!

How can I go about finding the fault? It happens when the isolator
switch is on or off! I'm wondering if the unit is faulty or has a
fixing nicked a cable in the wall? It's been up for a couple of Years
and only when the missus mentioned getting the same shock have I
thought I'd better get it resolved

fixing screw into a buried cable perhaps? I'd not be tolerating any
sort of noticeable leakage in a bathroom/shower situation due to risk
to other people than myself.

On 12/05/2011 08:26, deano wrote:
Its a metal (stainless steel) casing with a mirror door, has a canopy
over the door with 2 low voltage downlighters recessed into it.

Low Voltage Halogen? Probably an electronic 'transformer' is in circuit,
the design of which has some leakage issues particulary near the inlet
power filter. Disasemble and snap a picture of it?

--
Adrian C