"Electric Shock" from Coffee Machine

[luke_vibert_uk]

I used our Magimix coffee machine at the weekend and after use (as we always do) I unplugged it coiled up the mains flex/cable. As I did I inadvertantly touched the Live and Neutral pins of the plug and got one hell of a shock...big enough to make me jump across the kitchen, right arm, side of face numb and interesting metallic taste.

Bottom line its going in the bin to be replaced, however out of curiosity more than anything is this as a circumstance of some failure in the the house installation or some charge build up in the device?

I understand a physical test can only determin what caused this, however I've never experienced it from any other device ini the house or anywhere/anytime else?!

Bring on the science!

 

[Porque223]

I believe you felt a shock but I don't see how it is possible.
From your description you might have gotten more than 10 mA. Was your skin wet?

Post a schematic - I suppose there could have been a part failure in the coffee maker.

If you save the maker and have a multimeter and some resistors you can do some tests.

 

[Burnerman]

Is there a capacitor in there somewhere, guv?
John

 

[luke_vibert_uk]

No my skin wasn't wet, the only "moisture" would have been in the air from the milk frother, but that was some time prior to unplugging.

I have just plugged it in again just to see what would happen if left on to boil, then unplugged (lead out of the wall), then turn on the appliance. Sure enough the red light on the unit illuminated for all of half a second.

So it could be assumed that it is somehow storing electricity as Burnerman suggests...a capacitor.

Given the jolt I had its now in the bin.

 

[Porque223]

Let's say it uses a switch mode supply so the max voltage on the capacitor is 230 x sqrt(2) = ~ 320vdc.

You got >10 mA so your skin+body+skin resistance was less than 320/(>.01) < 32k.
IIRC that is a plausible somewhat high value for dry skin. I think 3k is a commonly used value with 300 ohms at the low extreme.

You maybe want to get checked out. Sometimes permanent damage does not show up for a while.

I have never gotten a shock that strong in my whole life but it depends on skin resistance, which varies greatly.

Does the maker warn against touching the plug? You may want to save that machine as evidence.

 

[luke_vibert_uk]

Thank you for the detailed reply.

The user manuals or box makes no reference not to touch the plug...but thats not something you'd necessarily warn about?...it shouldn't happen regardless should it?

To put it lightly its not an experience I'd be looking to repeat anytime soon. Both my face and arm went numb/tingling for a while and had a strange metallic taste in my mouth.

It's too late it's been skipped. The test this morning convinced me that its just not worth risking it.