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Cordless Crazy September 21st 06 10:30 PM

Voltage earthing through dishwasher casing/door
 
Found out earlier that when I plug my new Bosch dishwasher into a short extention lead (one without and earth wire for some reason (after investigating)) there is some residual voltage running through the casing/metal door lining. Upon touching the door I got a small shock (bit like and electric fence).

Checked it out and it seems to be of the figure of 50v running between the door and the floor i.e. with me acting as an earth!!

Bit more than I expected for residual voltage, as you would get with most appliances.

Once plugged in to the normal ring main and not with the crappy ext lead (that which is now confined to the shed as spare parts) the residual voltage reading drops to zero (as expected) as the integral earth wire is taking it away.

My question is: does this sound right or is the appliance faulty?

Chip September 21st 06 11:37 PM

Voltage earthing through dishwasher casing/door
 
On Thu, 21 Sep 2006 22:30:06 +0100,it is alleged that Cordless Crazy
spake thusly in uk.d-i-y:


Found out earlier that when I plug my new Bosch dishwasher into a short
extention lead (one without and earth wire for some reason (after
investigating)) there is some residual voltage running through the
casing/metal door lining. Upon touching the door I got a small shock
(bit like and electric fence).

Checked it out and it seems to be of the figure of 50v running between
the door and the floor i.e. with me acting as an earth!!

Bit more than I expected for residual voltage, as you would get with
most appliances.

Once plugged in to the normal ring main and not with the crappy ext
lead (that which is now confined to the shed as spare parts) the
residual voltage reading drops to zero (as expected) as the integral
earth wire is taking it away.

My question is: does this sound right or is the appliance faulty?


With a modern new dishwasher, it's likely to have electronic controls,
and thus a mains interference suppressor, which would have capacitors
to earth, resulting in a few volts (usually around half mains
potential) to 'frame' if the frame isn't earthed.

Usually the leakage is quoted to be at single digit or fractional
milliamps from a healthy filter.

--
There is not the slightest indication that nuclear energy will
ever be obtainable. It would mean that the atom would have to
be shattered at will.
- Albert Einstein, 1932

[email protected] September 22nd 06 12:03 AM

Voltage earthing through dishwasher casing/door
 
Cordless Crazy wrote:

Found out earlier that when I plug my new Bosch dishwasher into a short
extention lead (one without and earth wire for some reason (after
investigating)) there is some residual voltage running through the
casing/metal door lining. Upon touching the door I got a small shock
(bit like and electric fence).

Checked it out and it seems to be of the figure of 50v running between
the door and the floor i.e. with me acting as an earth!!

Bit more than I expected for residual voltage, as you would get with
most appliances.

Once plugged in to the normal ring main and not with the crappy ext
lead (that which is now confined to the shed as spare parts) the
residual voltage reading drops to zero (as expected) as the integral
earth wire is taking it away.

My question is: does this sound right or is the appliance faulty?


The voltage measured is as much a function of the meter as the
appliance, so 50v doesnt tell us much. But a shock form it means its
leaking more than it should, so yes somethings wrong. Earthed leaky
fixed appliances are commonish and dont seem to contribute to the death
figures, even though one would imagine them to be a risk.


NT


Andy Wade September 22nd 06 08:07 AM

Voltage earthing through dishwasher casing/door
 
wrote:

But a shock form it means its leaking more than it should, so yes
somethings wrong.


I don't agree with that bit. A Class 1 appliance like this could leak
up to 0.75 mA, which is more then enough to give a perceptible sensation
or tingle, but not a dangerous shock. There's no evidence here of
anything being wrong at all, apart from the OP having extension leads
lying around with no earth conductor.

--
Andy

[email protected] September 22nd 06 04:09 PM

Voltage earthing through dishwasher casing/door
 
Andy Wade wrote:
wrote:


But a shock form it means its leaking more than it should, so yes
somethings wrong.


I don't agree with that bit. A Class 1 appliance like this could leak
up to 0.75 mA, which is more then enough to give a perceptible sensation
or tingle, but not a dangerous shock. There's no evidence here of
anything being wrong at all, apart from the OP having extension leads
lying around with no earth conductor.


A tingle is not an electric fence like jolt where I come from.

NT



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