Girl in critical condition after fault earth electric shock

[Cyberdragon]

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.

It wasn't in the yard, it was probably on the side of the building and fed through the basement.

[Monkeh]

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."

Never said you should use a water pipe as an earth.

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."

Congratulations, things differ in AU. A TN-C-S system does not need a local electrode and the system does not need electrodes connected to it via massively inadequate conductors.

[BradC]

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.

It wasn't in the yard, it was probably on the side of the building and fed through the basement.

We don't do basements. It was a copper water pipe and we bury them in the dirt.

[Cyberdragon]

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.

It wasn't in the yard, it was probably on the side of the building and fed through the basement.

We don't do basements. It was a copper water pipe and we bury them in the dirt.

If you mean you only have taps that come up from the ground on posts, then something extremely fishy was going on. They must have put a plastic conduit around the pipe for some reason. Is this normal?

EDIT:
https://www.doityourself.com/stry/how-to-insulate-underground-water-pipes

Why the hell were they using metal pipes outside anyway?

[BradC]

Why the hell were they using metal pipes outside anyway?

Because that's how we do it. Absolutely nothing wrong with burying copper in the ground. We've only recently started the trend of using plastic for water. Until recently (and still if you want to build a house that is not disposable) we used materials that had a known longevity. Every house I've ever lived in (only 6 admittedly) has had full copper plumbing, and all the outdoor stuff was buried.

[sibeen]

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.

That's very true, Brumby. In Australia an underground water pipe was allowed to be used up until the 1976 version of AS3000 was promulgated, and there was no retrospective action enforced so that houses built before this time may have this style of earthing in place. If any upgrade work is carried out on the electrical installation in a house of this vintage the installing electricians is also supposed to upgrade the earthing to meet current standards. Sparkies normally hate working on these types of jobs as telling a client that upgrading a fuse to a circuit breaker also requires 'extra work' doesn't go down well.

The main reason for the post was someone had claimed that an earth stake is not the normal method of installation. Whilst there are going to be variances across countries, in Australia  it is a mandated method of installation and has been for over 40 years.

[Monkeh]

The main reason for the post was someone had claimed that an earth stake is not the normal method of installation. Whilst there are going to be variances across countries, in Australia  it is a mandated method of installation and has been for over 40 years.

I was directly responding to someone claiming it was normal for TN-C-S installations in the UK.

Context is for kings.

[raptor1956]

When I was a kid, about 7-8 years old or there abouts, I had washed my hands in a public restroom then went to dry my hands on what was then new -- the heated electric blower.  All was fine during the first cycle but when I went to start the second cycle, being a kid, I decided to hit the one next to it as well and I hit the metal power button of both driers at the same time.  I got the shock of a lifetime and I suspect the voltage was 220VAC instead of the normal 120VAC common in the USA -- higher powered devices like clothes driers etc are generally wired to 220 volts versus 120.

Well, yes, I did survive, but it could have been real bad if I'd been unable to remove my hands from the button and in this case it was fortunate that it was a button that's pushed versus a knob that needs to be grasped -- that would have made letting go much harder -- or impossible.

I don't know if it was outright incompetence of the electrician that installed them or if the documentation from the manufacturer was at fault -- I'd guess both.  Any decent electrician should have known about the potential.


Brian

[NiHaoMike]

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

My guess is that they're more likely to use lotion than guys do which would make them more conductive.

And one of the stories I wouldn't consider an electrical shock, although she definitely was taken by surprise!

[John B]

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.

That's very true, Brumby. In Australia an underground water pipe was allowed to be used up until the 1976 version of AS3000 was promulgated, and there was no retrospective action enforced so that houses built before this time may have this style of earthing in place. If any upgrade work is carried out on the electrical installation in a house of this vintage the installing electricians is also supposed to upgrade the earthing to meet current standards. Sparkies normally hate working on these types of jobs as telling a client that upgrading a fuse to a circuit breaker also requires 'extra work' doesn't go down well.

The main reason for the post was someone had claimed that an earth stake is not the normal method of installation. Whilst there are going to be variances across countries, in Australia  it is a mandated method of installation and has been for over 40 years.

I think that was the case in my current house: a pre 1976 house that had an earth stake installed when the whole electrical box was replaced a year ago. I'm all too happy to have one put in. In fact, I'm surprised it's only one. I would have thought with block size and varying earth moisture you'd probably want a few around the house.

Also this story prompted me to check the copper water and gas pipes. All are shorted* to mains earth ground.

*a couple of ohms depending on the location in the house. A few earth straps wouldn't go astray.

[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.

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

and what moron connected earth return wiring to water piping?

[BradC]

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

and what moron connected earth return wiring to water piping?

Why *wouldn't* you bond your pipework? It's buried in the dirt, it often connects to an electric hot water system (which is earthed) and it gives more earth surface area than the earth stake.

[digsys]

Why *wouldn't* you bond your pipework? It's buried in the dirt, it often connects to an electric hot water system
(which is earthed) and it gives more earth surface area than the earth stake.

You'd think so BUT in reality -
During Melbourne's last, very long hot dry period (8+ years), there were dozens of reported cases of plumbers getting quite serious electric shocks
working on buried plumbing. Some were serious enough to be admitted to hospital, and I believe there were even 1-2 deaths.
The ground had dried out so much that there was literally NO earth connection, and any meter faults turned the plumbing LIVE.
I noticed the issue, but luckily, instinct told me to bring in a friend, who happened to be a chief electrical inspector and working on the problem
at the time. It's why I posted above .. "WATER YOUR STAKE"

[Cyberdragon]

Why *wouldn't* you bond your pipework? It's buried in the dirt, it often connects to an electric hot water system
(which is earthed) and it gives more earth surface area than the earth stake.

You'd think so BUT in reality -
During Melbourne's last, very long hot dry period (8+ years), there were dozens of reported cases of plumbers getting quite serious electric shocks
working on buried plumbing. Some were serious enough to be admitted to hospital, and I believe there were even 1-2 deaths.
The ground had dried out so much that there was literally NO earth connection, and any meter faults turned the plumbing LIVE.
I noticed the issue, but luckily, instinct told me to bring in a friend, who happened to be a chief electrical inspector and working on the problem
at the time. It's why I posted above .. "WATER YOUR STAKE"

If that happens your grounding rods won't work either, so you're just plain screwed.

[BradC]

Why *wouldn't* you bond your pipework? It's buried in the dirt, it often connects to an electric hot water system
(which is earthed) and it gives more earth surface area than the earth stake.

You'd think so BUT in reality -

Bonding the pipework "gives more earth surface area than the earth stake". Dry soil in no way makes that statement less true.

Your specific instance requires a localised environmental condition *and* simultaneously a wiring fault to raise the potential of the pipework. Not bonding the pipework (which in the majority of cases would contravene AS3000-2007 5.6.2.2) is highly unlikely to have prevented that condition. If in that particular instance equipotential bonding was not required (ie no exposed conductive pipework, non-conductive pipework to all exposed plumbing) then, yeah you might be ok. But a wiring fault is still a wiring fault.

That, unfortunately is what happened in the instance being discussed in this thread, although being a State housing building and potentially being related to relatively recent works undertaken might conspire to see the real issues being papered over.

[sibeen]

During Melbourne's last, very long hot dry period (8+ years), there were dozens of reported cases of plumbers getting quite serious electric shocks
working on buried plumbing.

An example of safety precautions to counter this is a plumber working on a gas meter. If a pipe has to be disconnected from the meter then a large earthing strap will be connected between the pipe and the meter before any spanner is applied. It avoids any chance of sparking and minimises the possibility of an electrical shock.

[Brumby]

Five or six years ago I had a leak near the water meter and called in the water authority to deal with it, as the leak was on their side of the meter (luckily).

When the workers came out to do the repair, the first thing they did after digging down was the clamp a cable around the spot they were going to break the pipe.  Once broken, they then measured the voltage - and if it was above a certain threshold, they could not continue.  Fortunately this was OK and the fix completed rather quickly.

It was also the first time I had seen liquid nitrogen used first hand.  That was cool.

[mtdoc]

It was also the first time I had seen liquid nitrogen used first hand.  That was cool.

What did they use the liquid N2 for? Freeze the pipe upstream before breaking it?

[BradC]

It was also the first time I had seen liquid nitrogen used first hand.  That was cool.

Most plumbing stuff uses 1,1,1,2-Tetrafluoroethane. They spray the pipe to create an ice plug. It's interesting that they dump Kilos of that stuff into the air to freeze a pipe, but if I let any out of the A/C in my car I'm an environmental terrorist.

Liquid N2 would be much quicker. I've not seen them use that over here.

[Brumby]

Actually, I didn't ask - so I might have that wrong.

The technique used was to take a styrofoam cup and fit it around the pipe - yes, upstream to the cut - and then pour in a clear liquid that boiled feverishly, just as I have seen LN₂.  Zero flow check at a nearby tap and then work commenced.

[Muttley Snickers]

A mate of mine is both a plumber and gas fitter and he uses a carbon dioxide based freezing system, it's done by placing a sleeve similar to a velcro blood pressure wrap around the pipe to be plugged then turning on the bottle of CO2, I'm pretty sure the brand was Edro in Queensland.

[digsys]

  If that happens your grounding rods won't work either, so you're just plain screwed. 

errrrr that's why I mentioned twice now .. Water your stake ! (and me fitting a drip system). It's impractical to water all your water plumbing,,
and you generally don't expect trouble there, but an E-Stake only has 1 use. (also why I went with a 2nd much deeper one),

[Muttley Snickers]

Although this particular event appears to be a relatively rare occurrence I'm a bit surprised they couldn't or didn't incorporate monitoring of a dropped neutral or bad earth condition into the smart meters which could then have disconnected the active or at the very least generated an alert either locally or remotely until reset.

[BradC]

Although this particular event appears to be a relatively rare occurrence I'm a bit surprised they couldn't or didn't incorporate monitoring of a dropped neutral or bad earth condition into the smart meters which could then have disconnected the active or at the very least generated an alert either locally or remotely until reset.

We don't have smart meters. We have expensive digital meters that do some neat maths, and if you mortgage a kidney you can get some off peak action but they don't talk back and can't be remotely controlled. We might be a bit backward out West, but then we generally have an affordable and reliable grid too (although AEMO have moved in here recently, so we expect prices to rise and reliability to drop as they start screwing with the market).

errrrr that's why I mentioned twice now .. Water your stake ! (and me fitting a drip system). It's impractical to water all your water plumbing,,
and you generally don't expect trouble there, but an E-Stake only has 1 use. (also why I went with a 2nd much deeper one),

Lucky for me my stake sits less than 1000mm from the top of the water table.

Latest news on the young lady is some form of unquantified brain damage, and she's still unconscious.

I just can't figure it out though. If you turn the main on and get a shock from the meter box, wouldn't you turn it back off again?

[digsys]

I just can't figure it out though. If you turn the main on and get a shock from the meter box, wouldn't you turn it back off again? 

You and I might, we are used to HV zaps and everything related to them, but she was a young girl. She may have been disoriented, traumatized  or
physically disabled (muscle / injury), and had no idea of what had happened. Hope she makes it ok