An electrical experiment for Easter

Morning Chris

I am aware of 3 such type fatal accidents. One in the UK and one in Germany involving IPads being used in the bath.

I have also read the coroners report from the Anne Marie OGorman fatal accident which in volved an IPhone supplied whilst the victim was using an IPhone supplied from a long USB lead pluged in to a charger inserted in to a hall socket outside the bathroom.

There is no doubt that the poor woman died from ventricular fibrillation with additional evidence of burns to her body. I understand the plug in charger was not an OEM device. 

Your experiment was interesting and as a collector of AVO 8s I am aware of the value of the instrument still for some forms of testing. However the input impedance I think is 2000 ohms/volt. If you had used an electronic muti-meter rated for the the voltage, rather than one used for electronics, it will have produced as different reading due to the higher input impedance. 

Following the German accident I did some experiments on my own Ipad connecting a high input impedance voltmeter on the back I was detecting I remember correctly something in the order of 120V. I then used an oscilloscope to see the peak voltage and it was in the order of 180V with a distorted waveform.

Being immersed in water substantially increases the risk  of fatal shock hence all of the provisions of BS 7671 701. 

I believe investigations on the Irish fatal accident are still being worked on. 

JP

John Peckham said:

I understand the plug in charger was not an OEM device. 

John, thank you. It was a toss-up between the AVO and a Fluke digital meter.

I bought a new iPhone about 13 months ago. Because of the EU's Common Charger Directive, it uses a USB-C port rather than a proprietary one, and it came without a charger.

That makes very good sense from the point of view of avoiding waste, but it also opens the market to chargers which may be of a lower quality than OEM.

I wonder what sort of warnings come with a generic charger?

Sadly John, as you look abroad, there have been quite a few more in the last few years. 

As I can read German, there is a bit of a bias here to Austria, Germany and Switzerland; but I think we should assume that other places are probably similar at the one or two in hundred million years sort of level.

https://www.derstandard.at/story/2000146130189/handy-rutschte-in-die-badewanne-junge-italienerin-starb-weil

https://www.blick.ch/ausland/weil-ihr-ladendes-iphone-ins-wasser-fiel-24-jaehrige-stirbt-in-der-badewanne-durch-stromschlag-id16237529.html

https://www.sueddeutsche.de/muenchen/handynutzung-stromschlag-in-der-badewanne-16-jaehrige-stirbt-beim-musikhoeren-1.4375817

https://www.20min.ch/story/handy-faellt-in-die-badewanne-dann-ist-mariantonietta-16-tot-890987304474 

Interestingly, for females it is now approaching  the no of fatalities from twisted hairdryer flexes failing, the traditional continental mains in the bathroom Bete Noir.

Due to our regs, in the UK, hairdryers explode mostly in the bedroom but still in similar numbers.  (while the hairdryer in Spain fails mostly over the basin.. ) 

Given the no of tangled mess leads I have repaired over the years, it is clear that most such failures are non-fatal, and just result in unlady-like language.

There is no doubt in my mind, that this new trend shows that mobile phones are indeed bad for you.

Careful with that Ipad.

Mike.

The Electrical  Equipment (Safety) Regulations  requires manufacturers, importers and distributors to supply a Declaration of Conformity (DoC) for products they intend to place on the UK market. On of the provisions of this Statutory Instrument is to supply instructions in English with their products. 

JP

At the cheap end, none, and there are more than a few designs where the insulation creepage and clearance distances are far less that the proper standards require and a spot or two of condensation could bridge things out to the tune of a lethal no of mA 

This danish chap reviewed a load

https://lygte-info.dk/info/ChargerIndex%20UK.html lists some - any with a skull and crossbones review are non compliant.

Hs looks at many Europlug  models and a UK Example here 
https://lygte-info.dk/review/USBpower%20UK%20Plug%20style%20USB%20charger%201A%20AR1000%20UK.html 

Mike,

If you order off the web, and it comes through your letter box having set off outside the UK (or pre-brexit,  outside Europe), you are the importer, and it is down to you, not the person abroad you paid for it, to ensure it meets all necessary legislation and to make a suitable DOC. So not only do you get electrocuted or your house burnt down you are also responsible for grey market importing by buying direct from the  overseas supplier.

'not a lot of people know that' When perhaps they should.

Mike.

MapJ Assuming that my Ipad charger is plugged in to a 30mA RCD protected circuit and I am daft enough (Darwin having a day off) to get in to the bath with the Ipad connected by a long USB lead could the stored energy in the capacitors in the charger deliver enough charge (coulombs or micro coulombs)   to kill me?

MapJ Assuming that my Ipad charger is plugged in to a 30mA RCD protected circuit and I am daft enough (Darwin having a day off) to get in to the bath with the Ipad connected by a long USB lead could the stored energy in the capacitors in the charger deliver enough charge (coulombs or micro coulombs)   to kill me?

on its own, I really doubt it.
The minimum kill energy for a healthy adult is something over ten joules (*) for a one-shot capacitor discharge electrocution, and it has to be very unlucky so the current is directed via the right, well wrong really, body part.

Defibs use hundred joule sort of energies applied direct to the chest. Electric fences are limited by law to less than a few joules, depending where they are and if the wires are out of reach and similar limits apply to Tasers and similar weapons.

The problem is that the energy from the mains is replenished every half cycle, and in the case of a full mains voltage shock carries on burning through the skin, where most of the volt drop and therefore heating occurs, until a wetter lower voltage  internal contact is made.  

disconnected mains PSUs with defective bleed resistors can be dangerous once 1/2 CV2 exceeds 10-20 joules. 

( * note also that if we take the mains IEC safe disconnection times and very unlikely 1k Ohm body resistance as an example and say 250V, 250mA, 0.2 seconds that is comparable,  circa 60 watts for a 5th of a second would be 12Joules.)

There is also a risk of the RCD not actually tripping for a two wire mains lead in an unearthed plastic bath.

Mike