Electrical question

Jewelry Discussion
1

My Ultra Light kiln was plugged in but not yet hot, so I picked it
up to adjust its position–and felt an uncomfortable tingling along
my arm. Same thing happened when I used the metal spatula to adjust
one of the pieces on the kiln.

I figure the tingling was from the electrical circuit, and had
something to do with my standing barefoot on the tiles. It wasn’t a
severe jolt (else I wouldn’t be here today), but is there something
I can do (other than wearing shoes) so this can’t happen again? The
plug only has two prongs, both the same size, so apparently it
doesn’t matter how it’s plugged in.

BTW, I’ve sensed the same type of tingling (although much milder)
with other appliances (stereo receiver, sewing machine, serger) in
two different houses–but my husband can’t detect it. It doesn’t
matter which outlet I use, and it does matter whether or not my feet
touch the floor. A licensed electrician said the tingling was all in
my head: “Your house is only eight years old, so every outlet is
grounded. You can’t be feeling electricity.”

Janet

2

Janet, The first thing I would do is find a new electrician. If the
plug on your kiln only has 2 prongs, it is NOT grounded, and could
pose an electrocution risk in the event of a fault in the kiln. The
fact that the outlets are grounded means nothing if the kiln has no
ground prong on the plug.

You most cetrainly could be feeling electricity. Some people are
more sensitive to this than others, due to body resistance, which
varies from person to person. If you are feeling tingiling from your
kiln, that would indicate that there may be a breakdown of some sort
in the electrical insulation in the kiln. There are several ways to
test for that, and I would suggest that you have that looked into.
The proper instrument to use is called a “megger” or insulation
resistance tester. Places that rewind motors and transformers would
have one, and know how to use it. Most electricians would not. This
is the sort of problem that starts out as an annoyance and then
eventually kills someone. I would not assume that it is in your head.
Please do have this checked.

Please don’t assume that because someone is a licensed electrician
that they have a deep understanding of electricity. That is not
intended as an insult to elecrticians, it is simply that most of
thier training and licensing center around knowing code requirements,
laws, regulations, and appropriate wiring techniques. I respect what
they know, and the training that they go through to become licensed,
but I understand the scope of that training.

I hope I don’t sound too paranoid. I am an electrical engineer, and
have also taken lots of “electrician” training. I make my living
working around high voltage, and I ALWAYS treat “tingiling” feelings
as a very real threat to someones health and well being.

My opinion and 2 cents. Hope that is helpful. -AL

3 
A licensed electrician said it's all in my head

I assume you only asked the question of the electrician and that he
or she did NOT professionally and accurately check, each and every
outlet, with electrical equipment, to see whether all the outlets
are grounded properly and last but not least, also check the main
grounding rod or rods…

I am not an electrician, but I would suggest another professional
opinion, from an electrician who is willing to use proper
instrumentation, to accurately test the entire house / all the
outlets, at least the easily accessible ones… The electrician
should not be discounting your opinion as worthless, by saying “it’s
all in your head”…

The time to check your entire house should not take more than one
hour.

If it where me, I’d get a second, on site instrument tested,
professional opinion… Your house may not be grounded properly and
or, it may need to be grounded much better than it already is !

Good Luck
Rnl

4

That sounds like TERRIBLE advice to me. If you are feeling tingling,
and your husband isn’t, you may just be more sensitive to the leakage
than he is. If there IS leakage, it can KILL you under the right
(wrong) circumstances. PLEASE FIND SOMEONE WHO KNOWS MORE THAN YOUR
’LICENSED ELECTRICIAN.’ David Barzilay, Lord of the Rings

David Barzilay
Lord of the Rings
607 S Hill St Ste 850
Los Angeles, CA 90014-1718
213-488-9157

5

You are probably more sensitive than some people. But tingling is
indication of an equipment problem. You should get a ground fault
interrupter properly installed on the circuits you notice the
situation on. These are required on current US construction for
outside circuits and circuits near water. An 8 year old house
should have them but?? . They replace a standard outlet and
are inexpensive - about $10 US . Home depot will have them. They
can be homeowner installed but you do need basic electrical
knowledge and SHUT the circuit OFF before installing. There are
some pigtail extension cord units available.

see:

http://hyperphysics.phy-astr.gsu.edu/hbase/electric/gfi.html
http://www.mk-diamond-saws.com/accessory_mkac152610.html
http://www.northcoastmarines.com/GFI.htm

jesse

6

Janet,

Most ceramics that are used for kilns are slightly conductive at

higher temperatures so it is possible you are getting a tiny little
leakage current from the heating element. Best practice is to have
all devices where you might come in contact with a charged circuit
supplied via a ground fault interrupter type outlet. This will
greatly increase the safety for you and reduce the likelihood of a
fatal contact with the charged circuit. – Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160

@James_Binnion
Member of the Better Business Bureau

7

Put a copper rod three feet into the ground and wire the frame of
the kiln to it… You could also put an interrupter in the line
which will allow current to only flow one way and if the load is
like a short it will cut the power… the ground wire will keep
the load directed into the earth rather than you… Often time the
connections will corrode and provide such a high resistance the
power will try to go thru the case of the kiln rather than the
element. Check your connections and remember to unplug before you
attempt anything… Ringman John Henry

8

Janet

Your licensed electrician is probably wrong, it’s most likely
shocking you! I’ve been badly shocked by a kiln, and also by my
ultrasonic when touching a water faucet and the unit at the same
time. Everyone here has given you great advice. I’m just here to
agree and share my ‘shocking’ experiences. By the way, I’d have your
wiring checked. There is a small device available at most hardware
stores that simply plugs into your wall socket and indicates any
wiring faults. I think it costs about $5.

Jeffrey Everett

9 
   You should get a ground fault interrupter properly installed on
the circuits you notice the situation on.

I’d get behind this suggestion.

BTW Is this a tingling or a 60 hz vibration? Most appliances in my
experience do vibrate at the same rate as the AC current.

Bruce D. Holmgrain
JA Certified Master Bench Jeweler
http://www.goldwerx.com

10

Thank you for the advice. I did not realize that a 2-prong appliance
in a grounded outlet still presents a potential hazard.

I just learned that there are GFCI circuit breakers, to protect
large areas of the house. Is this as good as it sounds?
Receptacle-type GFCIs are required in so many parts of a house
(outlets in the kitchen, bathroom, garage, attic, etc.), I wonder
why the circuit-breaker-type are not the standard for new
construction.

Janet

11

I would ground it regardless of what the electrician says. You do
need to find a good spot (metal) on the kiln. Drill a hole in it
(1/16 in roughly) being carefull not to poke through anything inside.
Put a screw in the hole and wind a copper wire around it. The other
side of this wire needs to be attached to a grounding source. You
can buy a whole cable (3 wire-3 prong) at home depot, or just a three
prong plug (this would be a big time rig), or there are clamps that
attach around a copper pipe and also to your cable. In any event,
you’re trying to creat an easier path for the electricity to take.
If you need more help/info email me.

Stanley Bright

12 
Janet, The first thing I would do is find a new electrician. If
the plug on your kiln only has 2 prongs, it is NOT grounded, and
could pose an electrocution risk in the event of a fault in the
kiln.

Bravo! Furthermore, if a new house has two prong outlets, it may
not wired according to code. Are all your outlets this way? One
thing to look for is what is called a “Grounding Electrode” outside
your house near the meter or breaker box. It is a metal rod
approximately 1/2 to 3/4 inches in diameter that is driven into the
ground. There should be a wire clamped to the rod. The wire
ultimately should lead back to your breaker box. (Some building
codes may allow connection to a metal water pipe instead of a ground
electrode )

The purpose of the grounding electrode is to ensure that the wires
that should be at ground potential really are so. It is there to
ensure that it is the easiest path to ground, not you.

From your description, I would hypothesize (without testing, this is
only speculation as a place I would begin investigating) that your
Kiln has some contact between the metal and some wire inside that
conducts electricty. Possibly the white (“neurtal”) wire.
Furthermore, I would speculate that other outlets in your house did
have three prongs but that you have no connection with a grounding
electrode in your breaker box where all of the wiring from the third
prong is connected together.

The third (middle) prong on a plug usually is usedt to connect metal
housings of appliances to the grounding electrode. If no connection
exists, an electrical current from a short in one of your appliances
could be carried back through the third prong. Electric motors with
“carbon brushes” are notorious for low level shorts. As the carbon
contact material wears away, it leaves dust to make a connection
between the electric supply and the metal motor housing. The point
is that a household that does not have a physical connection to
ground could produce low level shocks from touching all of the metal
appliances. (In fact, since code requires a grounding electrode,
the green or bare ground wires and the white neutral wires are all
connected together in your breaker box. This means that either one
could be the source of your phantom current.)

In my opinion it is a poor idea to use a water pipe instead of a
grounding electrode. If a water pipe is used, there can be any
number of fittings used in the pipe that could break the connection
with ground.

Finally, there is one other possibility that I can think of: Some
ruarl power grids rely heavily on the ground itself as one leg of
the circuit that conducts electricty to homes. This is a rare
problem and to my knowledge, limited to ruarl areas. In such areas,
there can exist what are called “stray currents.” A stray current
means that there is a difference in potential between one area of
the earth and another. In such a case, you can actually get a shock
from a well grounded appliance merely by standing on earth that has
a different potential from that where the ground electrode is driven
in and then touching the grounded appliance.

This has been somewhat technical, but I hope it is a help. Please
note that I am not an electrician but have some college and trade
school education in electrical theory. Hopefully, this is
understandable to you, but if not, an electrician educated in
electrical theory should be able to understand what I am talking
about and test to see if anything I described is happening.
Finally…it is OK to look around an see if there is a grounding
electrode, however actual testing and wiring should be left to an
expert. Please don’t attempt to do this yourself. This is only
intended to give you some ideas about what might be happening.

Good luck…

Howard Woods
In the beautiful foothills near Eagle Idaho.

13 
   A licensed electrician said it's all in my head

My father said the same, when my sister and I told him we were
getting electric shocks from the stainless-steel sink, the faucets,
and the woodstove that had a water-heating reservoir in it. After
years of us getting bitten (HE certainly never washed a dish), he
finally had to replace the water heater and found that the heating
element had burst its cover and was hanging out in the water. My
guess is that maybe some of the insulation in your kiln is defective
or corroded and the same thing is occurring.

Tas
www.earthlywealth.com

14

Janet,

You have a grounding problem. If your kiln plug has only two prongs,
it is not properly grounded. If you are getting a “tingle” from
other appliances in your house, the wiring system in your house in
not properly grounded either. There are actually 2 "grounded"
conductors in a residential electrical system. One is the "neutral"
wire (white color) which comes from the center tap of the power
company’s transformer. The other one is the “equipment” ground wire
(bare copper). Even though both conductors are “grounded” they serve
two distictly different purposes. The purpose of the equipment
grounding conductor is personnel safety.

Even though the outlets in your house may be of the grounding type
(accepts 3 prong plug), they may not be properly wired. I suspect
that the system’s neutral conductor is also being used as the
equipment grounding conductor somewhere in your house. A hardware
store or building supply store like Home Depot has a test plug that
costs less than $10. They are very easy to use. You just plug it
into an outlet and indicators lights on the device will tell you if
the outlet is wired correctly.

It is not voltage that kills. It is current. It only takes about 5
milliamps of current to stop the heart. Your husband may not be able
to detect the tingle like you do simply because his body’s
resistance may be greater than yours. The tingle you feel is not
"all in your head". Just because an electrician has a “license”, it
does not mean he/she is competent. I strongly urge your to find an
electrician who will:

  1. Take you seriously

  2. Thoroughly explain to you and your husband what is wrong and
    what needs to be done to remedy the problem.

A competent electrician is a teacher as well as a technician. A
competent electrician relishes an opportunity to share his/her
knowledge rather than his/her ignorance.

Tim

15

electrician friend of mine said that it had to do with polarity.
Doesn’t matter when the house was built. Electricians make mistakes.
I had the same problem is some businesses built in the last 5 years.
but I don’t know how they solved the problem.
Try turning the plug over and plugging it back in.

16

Yea, it was all in my head everytime I got in the shower and felt a
major jolt whenever I would step on the metal drain, or touch the
handles or faucet. And then the repairman crawled under my house and
found a water pipe had sprung a pinhole leak that was spraying onto a
electric junction box and the electrical current was following right
back thru the stream of water, into my plumbing. Everytime someone
touched the water and something metal at the same time, they got a
jolt that was measured at aprox 30 amps. And that wasn’t in my head!!
It was in ALL parts of my body. My teenage son said “I thought it was
odd that my leg hurt everytime I got in there.” Ed in Kokomo

17

Hi All, Grounding Problems remind me of when I lived at Ft Hood,
Texas. We were living in a mobile home. One wet morning I let my
little dog out to take care of business. A few seconds later I
heard a loud Yip. I opened the door and there was my little dog
looking up at me with a shocked look in his eyes and shivering
uncontrollable. I figured maybe a cat got to him so next morning I
let him out again but this time I watched him. Now he was not too
bright because he did the same thing that bit him the morning
before. He went to the front of the mobile home and heisted his leg
and let go on the front metal wheel. Another Yip and I knew what
the problem was. The home was not grounded correctly. The manager
of the trailer park gave us a cord to connect our home to the
property outlet. It was a home made cord that had the black and
white wired reversed. I suggest you find another electrician. Lee

18

Janet, From your description it sounds like there is short between
the wiring in the kiln and the case. Grounding the case of the kiln
to the ground on the wall outlet will prevent the shocks if its a
high resistance short, or blow the fuse if its a dead short. The case
is probably required by code to be grounded. BUT, and a big but, is
the fact that if you touch a grounded case (ie. hand on the door
handle) AND touch a coil you will get a rather nasty arm to arm
shock. I’ve run kilns with both 2 wire and 3 wire grounded hookups;
with a grounded case I make SURE that the coils are OFF before I open
the door. Electro-shock learning aids can be very effective. A GFI
outlet would be a good idea too, along with another electrician who
is more interested in resolving your concerns rather than just
dismissing them.

Jeff

19 
       A licensed electrician said it's all in my head

My father said the same, when my sister and I told him we were
getting electric shocks from the stainless-steel sink, the faucets,
Adding to my rather long response yesterday: Your sensitivity can
vary by how much moisture is in your skin and what kind of footwear
you are wearing. Women are more likely to use hand cream and wear
thinner soled shoes.

I also was quick to judge the electrician based on the “two pronged
plug.” If the "recepticle"was two pronged, then it wasn’t according
to code. A two pronged plug can plug into a three recepticle that
is able to receive three prongs. That has nothing to do with the
wiring of the home.

You may also want to check with your local power company. They
often send out someone that has experience checking for shock
hazards. They will probably charge for the visit unless it is
something that is their fault.

Finally, a GFI is an excellent safety backup system to detect
failures in a wiring system and prevent injury. However, if you
already have a failure in the system, then the GFI becomes the
primary protection. Sooner or later everything fails. If a GFI is
used as primary protection, it’s failure could lead to injury or
worse. Also, it takes some small amount energy to trip a GFI. If
the original problem isn’t fixed, that energy could origninate from
what flows through your body. In all likelyhood, that amount of
energy for a small period of time (measured in microseconds) would
never be dangerous. I just have a hard time trusting the word
never.

Howard Woods
In the beautiful Foothills near Eagle Idaho.

20

I’m also a retired electrician but I read Orchid daily. I’m an
Australian so things are a little different over here but many things
are the same. For a start we use 240 volts and 50 hertz mains. Over
here, I often came across your complaint. These “tingles” can
sometimes be due to very small voltages and the common “leccy” meters
may not even detect them. I will mention some remedies throughout
the article and suggest testing methods at the end.

If you do decide to “clean up” any earth connections or bonds as
mentioned below, PLEASE TURN OFF THE POWER FIRST at the main switch.
If there is a fault in your building, it may be passing current
through the connection you are undoing and you will complete the
circuit. Not good. We don’t like to reduce the Orchid newsgroup’s
membership!!

It is best if a qualified electrician does the job but nothing says
you can’t be a pain and supervise them (you’re just extraordinarilly
fussy) or get them to allow you to do some jobs with them
supervising.

"Tingles"may have many causes.

Basically, the earthing system in a building takes any (earth
leakage) fault current to ground for safety. If there is any current
leaking to earth and the earthing system has any resistance and you
form a better earth path than the building earthing system, then you
will get a shock or a “tingle.” As these “tingles” may be of very
low voltages - many electricians just discount them as they “aren’t a
shock hazard.” If the electrician’s meter isn’t sensitive enough to
read the voltage then they may consider it an "all in their head"
complaint and not seriously investigate any further.

Worse still, if there is a fault then a high resistance earthing
system may cause all of the earthed items in your house to be sitting
at any voltage up to your mains voltage. I have seen a "tingle"
complaint where all of the house was floating at almost mains
potential!! (Including the metal switchboard that I had to open to
turn off the power).

  1. Main Earthing System

The problem was often a bad earthing system often requiring an
additional (or two) earth stake (preferably extra long) driven and
connected to the existing earth stake. This was particularly the
case if there wasn’t an earth stake used but only a connection to the
metal water pipes (old system here) or soil conditions that weren’t
conducive to a good connection - sand, soil in drought etc.
Sometimes people would regularly water the ground around their earth
stake to ensure a good conductor. The connection to the earth rod
must also be a good connection though. Please see the comments
about this in Section 2.

Another problem is people cementing around the earth stake - it can
get dry and nothing can be done about it. We suggest a piece of 3
inch or 4 inch PVC pipe be used around the top of an earth stake to
keep the concrete away from it when cementing to allow access to the
weather.

A related problem was “tingles” from water taps - again it can be
the earth stake or the “earth bond” which is a wire joining metal
water pipes to the earthing system. Bad connections are a problem.
It also helps in the earth bond is done in larger cable then normally
used, especially if the bond runs any length, as this reduces the
resistance. Any reduction in resistance can be helpful when we are
dealing with small voltages.

Sometimes a section of piping is changed with PVC or polythene and
the pipe has sections insulated from each other. The water will
conduct the electricity so the separated metal sections need to be
"bonded" or joined together as well so that any current is goiing
through the pipework or wire and not the water. We occasionally also
had to bond the Hot and Cold pipes together under sinks etc.
Although rare, it sometimes worked - especially with newer "fancy"
fittings.

  1. Good Earth Connections

Earth clamps or bonds to pipes or earth stakes must make good
electrical connections. If the clamp or pipe or earth stake has any
corrosion or oxide film where connections are made, it may need to be
replaced or the surfaces cleaned up with steel wool or emery and
redone. Over here, connections are then spray painted with spray
galvanising paint to seal them from the air and moisture.

  1. Bad connections to the Utility Power system.

A bad connection to the Utility Power system can be problem too. In
Australia the neutral conductor is bonded to the earth at each
installation. If the neutral connection to the building becomes high
resistance (for some reason they will sometimes burn off) then the
earth system has to carry all the current. Typical complaint here is
that the lights dim when we use the stove. I don’t know if the same
system is used in the USA (we call it the MEN - Multiple Earthed
Neutral system here - terminology may be different).

  1. Plugs, Sockets, Leads, Connections.

Although lower down the scale, the contacts in your power outlets
must be making contact and not corroded, overheated, or sprung apart.
Loose or oxidised wiring or connections in the fixed wiring can also
be at fault. Similarly, connections at plugs and sockets on leads
must also be in good condition and socket contacts in good condition.

Extension cords are common problems as far as having burnt or
corroded connections. Too small of conductor in any extension cord
adds to voltage drop and resistance problems. Again, a higher
resistance to earth allows you to be a better path than the cable.
Bigger is better, especially if you’re sensitive and large cabling is
vital for high current items (helps stop fires too). Transparent
plugs and sockets are available in Australia and allow visual
inspections without dismantling items.

If your plugs or sockets show any signs of heat damage they should
be replaced. Plug pins should not be corroded or heavily oxidised as
that can be a problem. Plug pins can be given a light "polishing"
but plugs should be replaced if heavily corroded or showing "burn"
marks. If you fit a new plug and notice thatit has arc marks again,
then you have a faulty socket. A faulty socket can destroy a new plug
very quickly and requires both the plug and socket to be replaced - a
pain if it was a new plug.

Any connections to an item’s metal work for earthing must be tight,
clean and not corroded or oxidised and the earthing screw not
painted. This last item seems common sense but I have seen many
items where the connecting lug or screw has been well painted and
impossible to ever be a conductor.

  1. Electrical Fault.

If you have an electrical fault to earth in your installation then
the earthing system takes that current to ground for safety. If the
earthing system has any resistance (see item 1 above) then it may
cause all of the earthed items in your house to be sitting at a
voltage somewhere between zero and your mains voltage.

If you form a better earth path than the building earthing system,
then you will get a shock or a “tingle.”

If the mains authority has a transformer or other equipment nearby
with a fault to earth (especially on the high voltage side), then you
may end up with a “voltage gradient”. This is because the ground has
resistance so the voltage doesn’t drop immediately at the earthing
point but reduces over a distance. You can be quite some distance
from a high voltage fault and get a voltage gradient effect. The
worst case scenario is if your body is in water e.g. swimming pool,
when a gradient of a few volts per yard can kill you.

  1. Ground Fault Interrupter (Safety Switch, RCD or ELCB)

Ground Fault Interrupters (called Safety Switch, RCD or ELCB amongst
other names in Australia and elsewhere) are great devices. They work
well but do have limitations. Operation just takes the common sense
fact that the current into an appliance through the Active or Hot
wire should equal the current out through the Neutral wire. Any
imbalance is leakage to earth i.e. a fault.

Testing Necessary

A Ground Fault Interrupter is normally partly mechanical in nature.
They must be tested (operation triggered) periodically to ensure that
the mechanics don’t freeze up and that they haven’t been damaged by
surges etc. Whilst they normally have a test button for testing,
there are cheap test devices available at electrical wholesalers that
allow you to test the actual tripping current - there are also very
expensive test units as well.

Why it won’t save you.

A Ground Fault Interrupter (Safety Switch, RCD or ELCB) WILL NOT
operate if you go between the active and neutral conductors whilst
insulated from earth. There is no imbalance, no earth current; it
sees you as another appliance working correctly and happily frying.
They also will not operate if the imbalance is too low. Thankfully
they are fairly sensitive unless damaged by surges etc…

Tests have also shown that they normally will not operate in the
"appliance drops into the bathtub with person in it" scenario. At
least here in Australia, PVC waste water piping means that the bath
tub is not an effective earth and you again have no imbalance…

If you have wet skin or puncture the skin the shock effect may be
far greater so they may not be as effective.

  1. Testing your electrical installation earthing.

This is best done by an electrician. In Australia the rules
stipulate a maximum of 4 ohms from the earth stake to any socket
earth. This is a maximum value and should be lower - the lower the
better.

Testing is done by using a resistance meter or Ohm meter. The power
should be turned OFF at the main switch as any fault may energise the
earth pin.

It is best if the test is made to every power outlet (i.e. both
sockets of a double outlet) and that the method of testing an outlet
is by plugging a plug into it with only the earth wire being
connected to the plug as a meter connection - using a test probe in
the socket won’t detect a sprung earth and will scratch through quite
heavy corrosion. This ensures that the socket is making good contact
on the earth pin. Trying to wriggle the plug to see if it affects
the reading also helps show any faults. I have seen earth pins so
widely sprung that they could never make contact with a plug but the
test probe finds them easily.

The insulation resistance of each circuit should be tested
individually with and without appliances - plug all your appliances
in for a total insulation test under “operating conditions” and/or
test them individually. It is amazing how a few "slightly leaky"
appliances add up.

  1. A few other items to watch.

If you only occasionally use items with a heating element (tubular
metal style) and you are in a moist environment (like we are here in
the tropics) then they may absorb moisture. These tubular elements
have a fine powder inside to insulate the internal element from the
casing. This poweder is hydroscopic - it sucks up moisture - and the
end seals are not perfect. When you plug it into a Ground Fault
Interrupter (Safety Switch, RCD or ELCB), the leakage may be
sufficient to trip it. This may be worse here because of our higher
mains voltage. The standard remedy is to plug it into a socket not
protected for earth leakage and heat it up. It may take 5 - 10
minutes or even 30 minutes or so. It is then generally OK for a year
or so. My switchboards (4) each have a socket fitted just for that
use.

BTW, “tingles” can also be caused by faulty elements in electrical
hot water systems - a fault that can get overlooked as they may still
be operating but faulty.

  1. Static Electricity

If you are in an environment with very dry air and especially if
there is “lino” or carpet or synthetic floor coverings, you may be
feeling static electricity discharges. In dry summer conditions, we
get complaints about polishers that are faulty - regularly that is
the problem. Try touching something that is grounded and then try
touching the first item again to see if it still “tingles.”

  1. Double Insulated items with Metal Cases.

The common item is a Stereo System or Radio Transmitter. The
tingles can be due to coupling by capacive or inductive effects. I
have seen a radio transmitter that really “bit” but was officially
"safe" and legal. The remedy is an earth wire fitted to a convenient
earth. This is allowed in most countries - if I remember correctly
it is termed a “functional” earth and not a “protective” earth. It
is normally illegal to fit an earthed cord to a double insulated item
but it appears that you can fit an extra earth wire - wierd huh?

I hope this helps. Regards, Brian Symons.
Sunny Mackay, Nth Queensland, Australia.