Girl in critical condition after fault earth electric shock

[EEVblog]

http://www.watoday.com.au/wa-news/perth-girl-remains-in-critical-condition-as-investigations-into-electric-shock-continue-20180305-h0x1ju.html

Perth girl remains in critical condition as investigations into 'electric shock' continue

A fault in the earthing system outside a Perth public housing property likely caused an 11-year-old girl to suffer a life-threatening electric shock from a garden tap, WA's electricity regulator says.

Denishar Woods is fighting for her life at Princess Margaret Hospital after touching the outdoor tap at her family's Beldon property on Saturday night.

EnergySafety director of electricity compliance Mike Bunko said the fault was likely an upstream "open circuit neutral", which could be caused by corrosion, a loose connection and in some cases, poor workmanship.

Mr Bunko said residual current devices would not protect against an open circuit neutral.

"The fault is preceding the RCD," he told 6PR radio on Monday.
"If you get a fault upstream, generally before the meter where the electricity is coming in, the RCD can't see it and can't operate."

WA housing minister Peter Tinley said the Department of Housing was looking into the incident and cooperating with Energy Safety, which is undertaking an investigation.

"We will get to the bottom of this," Mr Tinley told reporters.
"We just hope that she pulls through.
"This is a tragedy that nobody should have to endure."

Mr Tinley said the family would be immediately accommodated elsewhere if they didn't want to remain at the property, where the power has been cut off to make it safe.

"If we have to put them in a hotel or a motel, then we'll do that," he said.

"Clearly, they wouldn't have a lot of faith in the property. They won't be expected to move back into it."

He said he was not aware of family's claims they had complained more than once about short-circuiting.

Mr Bunko said open circuit neutrals were less common in new houses because they had a lot of plastic pipework.

"If you do get electric shocks off taps or you notice that your lights are dimming for no good reason, then you need to report it to the network operator," he said.?

Following the incident, neighbours reported hearing a "massive bang" at the home on the corner of Eddystone Avenue and Sandalford Drive, and emergency services quickly came to the scene.

Denishar was revived by paramedics on the way to Princess Margaret Hospital, but again lost consciousness.

She has now remained in a coma for over 48 hours.

On Monday morning, she was in a critical but stable condition.

Her mother, Lacey Harrison, told 9 News Perth she tried desperately to help her daughter.

"I went to grab my baby because I didn't realise how stuck she was to this energy," she said.

"It dragged me onto her and I dropped down on the other side half way under my car.

"She was on one side frying, I was on the other side frying."

According to the University of Western Australia's personal electrical safety course, a shock around 230 volts AC alone can be fatal.

"Under normal circumstances, voltages below 50 volts are generally not harmful to humans," their programme reads.

"However, they must still be treated with respect.

"Electricity supply systems typically operate at 240 volts AC phase to earth and 415 volts AC phase to phase.

"A shock at these voltages can be fatal."

National Electrical and Communications Association executive director Garry Itzstein also echoed these concerns.

"Receiving an electric shock through a garden tap is very rare," he said.

"Without knowing the circumstance, it is impossible to say what caused this however, there are a number of potential causes that will need to be looked into."

Electrical work had recently been done on the home, and Denishar's mother said she had experienced a "burning electrical smell on and off" since the work had been completed, the ABC reports.

Mr Itzstein said there was a possibility the work wasn't up to Australian standards, or previous maintenance, repair work, additions or changes may have damaged the existing electrical systems.

"Home owners should also have the property's RCD units regularly inspected and tested. RCD's are the primary defence against electrical shocks so it is imperative that they are in place and regularly checked and tested," he said.

[dmills]

Ouch!

Earth exported from the equipotential zone in a TN-C-S install, then an upstream neutral fault from the sound of things.
Not common, but it can happen, which is why you are really not supposed to do that, but a plumber fitting an outside tap will generally not spot the danger.

Regards, Dan.

[grumpydoc]

Ouch!

Ouch indeed

Earth exported from the equipotential zone in a TN-C-S install, then an upstream neutral fault from the sound of things.
Not common, but it can happen, which is why you are really not supposed to do that, but a plumber fitting an outside tap will generally not spot the danger.

So, what's the fault current path? - from live, via equipment neutral/earth to (presumably) "earthed" tap thence to true ground?

Seems almost unreasonable to expect a plumber to be aware of the risk.

[station240]

https://www.9news.com.au/national/2018/03/04/21/31/perth-girl-fighting-for-life-after-electric-shock-at-home

"According to PerthNow, Ms Harrison had reported other power problems at the home in recent months including a “burning electrical smell” where an electrician was unable to find a cause."

"She claims she reported a problem with the electricity at the public housing property to the Department of Housing, about an hour before her daughter was shocked"

http://www.abc.net.au/news/2018-03-05/denishar-woods-remains-in-critical-condition-after-electric-sho/9510242
"She said her organs reached 38 degrees Celsius and she was on a cooling pad in hospital to try to limit the damage."
"Ms Harrison she was out watering in the garden on Saturday night when the power to the house went out.
When she went to the meter box to turn the power back on, she received a small electric shock.
She said she contacted the Department of Housing emergency contact line to notify them of the fault, but she said no one warned her not to touch anything."

Someone in the Department of Housing (WA) NEEDS to go to jail for this shit.
All the warning signs were there that the house was live at mains voltage.
The power went out because the Neutral was completely disconnected due to a fault, possibly underground. When the running tap was touched the circuit was completed, earth on house (tap) to ground, to earth in street power cabling.

related stories
http://www.abc.net.au/news/2018-03-05/what-causes-taps-to-be-electrified/9508664

What could have been done ?
1) Touch nothing on, in or attached to the house.
2) Switch off the main breaker, using an insulating material, like a length of timber, plastic rod etc.
3) Properly investigate the original complaints, months ago, and fix it before be became lethal.
4) Report a live meterbox to the power company, who will warn of the dangers and rush out to make it safe.

Here is hoping the girl and her mother are OK, longer term.

[station240]

Earth exported from the equipotential zone in a TN-C-S install, then an upstream neutral fault from the sound of things.

So, what's the fault current path? - from live, via equipment neutral/earth to (presumably) "earthed" tap thence to true ground?

In Australia, there are multiple Earth stakes and Neutral to Earth ties.
The house has 1 earth stake and one jumper between that Earth and Neutral. Same for power poles (metal ones anyway), transformers, and underground cable junctions.

So a broken Neutral between the house and street, leaves the only return path as being the ground via two earth stakes. The copper water pipe with running water was a lower resistance current path, just needed a human to complete it. Active is fuse for 80amps for the meter, so everything drawing power in the house was using that completed circuit.

[dmills]

So, what's the fault current path? - from live, via equipment neutral/earth to (presumably) "earthed" tap thence to true ground?
Seems almost unreasonable to expect a plumber to be aware of the risk.

That's the one, it is even nastier then it sounds because if the fault is somewhere upstream, even switching off the incoming isolator will not make it safe, that switch isolates live and neutral in the -S part of the arrangement, but the fault lies in the combined neutral/earth -C- part and so other loads will still drive the local 'earth' away from the ground.

UK practise is that there is a ground rod at every house in these installations (As well as, in theory, at every buried cable junction) so as to limit the voltage rise in the event of this fault (Multiple earthed neutral), but a combination of lost neutral and touching a metal fitting outside the zone with (probably) wet hands, while on wet ground, just OUCH!

Within the house all the exposed metal is supposedly firmly bonded together (Pipes, taps, the bath) by fairly butch conductors to ensure that even in the event of such a fault it is not possible to get between it and a low impedance ground (This is the equipotential zone), but an outside tap on metal pipework, yea that's harsh.

These systems are actually not an unreasonable design choice as they are actually significantly safer MOST of the time then TT systems (Separate earth relying on a rod) which can wind up with such a high loop impedance that even a 100mA RCD will not trip on a fault. TN-S (Totally separate earth back to the transformer) is usually cost prohibitive (and has some issues of its own).

Incidentally, TN-C-S is a pain when you are a radio ham and thus want lots of wire outside the zone....

Regards, Dan.

[sokoloff]

"Ms Harrison she was out watering in the garden on Saturday night when the power to the house went out.
When she went to the meter box to turn the power back on, she received a small electric shock.
She said she contacted the Department of Housing emergency contact line to notify them of the fault, but she said no one warned her not to touch anything."

Someone in the Department of Housing (WA) NEEDS to go to jail for this shit.
All the warning signs were there that the house was live at mains voltage.

Who? The person who took the call that an occupant reported a shock when resetting a circuit breaker? Is that person expected to be qualified to know, from a telephone report, of the condition at the property? That's expecting WAY too much out of a call center agent, IMO.

[senso]

Would plastic water pipes prevent this?

I know that water is a conductor, but that as good as a metal pipe, also, why would the girl get shocked if the metal pipe is buried, so it should have better earthing than someone standing on grass with shoes.

[DenzilPenberthy]

The EXACT same thing happened to me when I was a kid.

I'd been playing with  the garden hose, soaking wet ground, bare feet. Went to turn off the garden tap and got a huge electric shock.  I couldn't let go and was stuck there while my friend ran to get my mum who kicked me off the tap. It affected our whole neighbourhood. 

Fortunately I'm right handed so most of the current would have flowed down my right side, away from my heart. I could very easily have been killed.

[sokoloff]

I know that water is a conductor, but that as good as a metal pipe, also, why would the girl get shocked if the metal pipe is buried, so it should have better earthing than someone standing on grass with shoes.

I imagine the metal pipe was service from the house, not a buried pipe. Imagine a pipe that goes through the basement and emerges at a hose bib a few feet above ground on the outside of the house.

[dmills]

A foot or two of plastic pipe going thru the wall will at least make this particular fault much less nasty, still tickle a bit probably, but you would not get the kind of current that causes a serious increase in temperature in a human body, tap water is not usually that conductive.

I await a report of what actually happened with interest, because while a TN-C-S neutral screwup seems most likely, we don't actually know.

Regards, Dan.

[jordanp123]

I'm unfamiliar with the Australian regulations but I'm going to assume their close to the same as the us in this regard (Neutral and ground bonded at Utility pole then only neutral and power coming to the house - then neutral and ground bonded again in the main panel- With the water also grounded from the house ground). I've gotten a zing before on the actual ground rods, utility neutral burnt open for a overloaded neutral, sometimes you'll also see the TV lines getting hot and melting due to the alternate current path.

[dmills]

Don't forget that most of 230V land does not do either split phase or one transformer per customer, so the lost (or high Z) neutral tends to have a fair bit more bite to it depending on exactly where the fault occurs.

Not that this is a common fault in a TN-C-S install, you hear about roughly one or two a year, and it is usually obvious when it happens on a three phase feed as the neutral wanging around makes stuff see all sorts of random voltages and lots of stuff usually blows up. Often the root cause is copper thieves removing the neutral bar at the local sub station!

This one feels like a fail on a single phase setup, but who really knows until someone publishes a proper report?

Regards, Dan.

[Mechatrommer]

too much speculation... for whatever reason (be it neutral or live), how can electricity touches water pipe in the first place? if anyone has to go to jail, its the person who made the installation.

[Monkeh]

UK practise is that there is a ground rod at every house in these installations

Ah.. no, not really. Rods are generally not used with TN-C-S supplies.

too much speculation... for whatever reason (be it neutral or live), how can electricity touches water pipe in the first place? if anyone has to go to jail, its the person who made the installation.

.. the pipe is earthed. If you lose the earth..

[metrologist]

My house cold water supply became disconnected from earth at the supply - because a plastic supply line replaced the old galvanized pipe. I believe it was acceptable to attach ground to a cold water pipe within the dwelling. A failed neutral and other short to live could energize all of the water taps. Fortunately, the supply is still connected to long outside runs to irrigation. Also, the electricity was rewired in time to require an additional ground rod at the water supply - where the panel is required to be grounded to the water supply pipe. I still do not like it, but that appears to be the code.

[dmills]

The water pipes inside the house form part of the equipotential bonding network (That is they are all wired firmly together and connected to the suppliers "Earth terminal"). This bonding ensures that even if something bad happens to the combined earth/neutral people inside the house are reasonably safe because everything they touch is at the same potential.

That "Earth terminal is really a connection to the suppliers neutral conductor which should be firmly bonded to earth at multiple points.

My suspicion (Without really adequate evidence) is that the combined neutral/earth conductor failed somewhere upstream, at which point all the pipework becomes live (To a greater or lesser extent) via the bonding network (Which keeps things reasonably safe as long as you are inside the equipotential zone), trouble is the kid was outside the zone and touched metalwork that exported the "Earth" from the zone.

I surely do see earth rods used in TN-C-S installs, generally with a 16mm^2 cable attached, but I do a lot of radio work so that might be something specific to those sites (Which should probably really be TT anyway).

Regards, Dan.

[Monkeh]

I surely do see earth rods used in TN-C-S installs, generally with a 16mm^2 cable attached, but I do a lot of radio work so that might be something specific to those sites (Which should probably really be TT anyway).

It's really not the norm, though, or correct.

Think about this: If I install an earth rod in my house, the only one installed on my entire street (of 30 houses), and we completely lose the supplier neutral.. what happens to my 16mm² straight concentric supply cable when it's handling return current for 30 properties? Considering things here are fused at 300A per phase or something along those lines..

Do you really expect a DNO to trust that every house will have a properly installed earth rod to supplement their installation which is entirely out of their control, they cannot inspect, and they cannot test?

[gildasd]

Trying to twist my head around this incident and Belgian rules, I really really really want to avoid the possibility of this happening.

As far as I know, in Belgium, it is illegal to use piping as earth conductor.
Metal Piping can be earthed, but to the earth, not as the earth.
All grounds must be connected to a main ground then to a stake whose length, position and depth below the surface are all regulated (I have two; one fore, one aft).

All my water piping is PEX btw.

[Marvo]

Best way to avoid it happening is to have an low impedance earth rod at every premises when the supply is PME'd TN-C-S and bond all services. The Ra of the local earth rod needs to be sufficiently low to ensure <50v touch voltage under full supply current.

[Cyberdragon]

They did the whole thing ass backwards. Assuming all copper plumbing in the house was connected to the ground, you only do this if the pipes are already grounded through a buried metal pipe. Pipes can sometimes become isolated by water meters and such, but you are supposed to jumper across them. So either they illegally hooked up the ground to unearthed piping, or there was a modification to the plumbing that isolated it and the idiots didn't check it.

[sibeen]

I surely do see earth rods used in TN-C-S installs, generally with a 16mm^2 cable attached, but I do a lot of radio work so that might be something specific to those sites (Which should probably really be TT anyway).

It's really not the norm, though, or correct.

Think about this: If I install an earth rod in my house, the only one installed on my entire street (of 30 houses), and we completely lose the supplier neutral.. what happens to my 16mm² straight concentric supply cable when it's handling return current for 30 properties? Considering things here are fused at 300A per phase or something along those lines..

Do you really expect a DNO to trust that every house will have a properly installed earth rod to supplement their installation which is entirely out of their control, they cannot inspect, and they cannot test?

I don't know the British standards, but I do know the Aus/NZ relevant standard for this (AS/NZ3000) and I would actually be a bit surprised if the Brit standard varied considerably from the AS/NZ.

In AS3000 section 5.3.2.2 states in part "Sprinkler pipes or pipes conveying gas, water, flammable liquid or other conductive non-electrical service enclosures shall not be used as an
earthing medium."

Next up we have

5.3.6.1 General
"The connection of the electrical installation earthing system to the general mass of earth shall be achieved by means of an earth electrode."

I also just wandered out to the front of my property and there, located directly under my switchboard, is an earth stake which I decided to take a photo of In general every house in Australia will have an earth stake which will be connected to an earth bar within the incoming switchboard and the neutral and earth will be bonded within that board.

[Bud]

Why it is always girls in these electric shock stories? I think there were 3 lastly and each time it was a girl.

[digsys]

DON'T forget to water your stake during long dry spells !! I have a plant drip feed on mine. During our last very long dry spell, app 8yrs,
E potential was climbing to 100V+ (depending on loads). Added a 2nd much deeper spike and lots of water. All good since.
I knew something was wrong when isolation / test equipment / earth leakage designs were playing up.

[Brumby]

I surely do see earth rods used in TN-C-S installs, generally with a 16mm^2 cable attached, but I do a lot of radio work so that might be something specific to those sites (Which should probably really be TT anyway).

It's really not the norm, though, or correct.

Think about this: If I install an earth rod in my house, the only one installed on my entire street (of 30 houses), and we completely lose the supplier neutral.. what happens to my 16mm² straight concentric supply cable when it's handling return current for 30 properties? Considering things here are fused at 300A per phase or something along those lines..

Do you really expect a DNO to trust that every house will have a properly installed earth rod to supplement their installation which is entirely out of their control, they cannot inspect, and they cannot test?

I don't know the British standards, but I do know the Aus/NZ relevant standard for this (AS/NZ3000) and I would actually be a bit surprised if the Brit standard varied considerably from the AS/NZ.

In AS3000 section 5.3.2.2 states in part "Sprinkler pipes or pipes conveying gas, water, flammable liquid or other conductive non-electrical service enclosures shall not be used as an
earthing medium."

Next up we have

5.3.6.1 General
"The connection of the electrical installation earthing system to the general mass of earth shall be achieved by means of an earth electrode."

I also just wandered out to the front of my property and there, located directly under my switchboard, is an earth stake which I decided to take a photo of In general every house in Australia will have an earth stake which will be connected to an earth bar within the incoming switchboard and the neutral and earth will be bonded within that board.

That is my understanding of the current rules - but it was not always so.

In years gone by, it was not uncommon for the water piping to be used as the household earth.  When the new rules came in, there was no mandate for all properties to change - but I believe if you were to have any electrical work done, then you needed the separate earth spike put in.


In this particular instance, I am also curious as to the current path - especially if the tap is out in an open yard with a buried pipe feeding it.