Today I experienced the worst electric shock my career

[mainline]

Are you suggesting they hold the second probe and make themself part of the test circuit?

I'm suggesting that he grounds the 2nd probe and that there was an obvious ground nearby, as otherwise he wouldn't have had a shock of that magnitude.

A decent 2 probe tester would be of a high enough impedance to not cause anything like the shock he had, even if he did hold the other probe.

Probably no more of a risk than using the unsafe screwdriver type, which relies on making yourself part of it.

 

[LukeD]

I am way too OCD . I tend to wipe out the whole board if possible when dealing with issues outside . Ive seen a guy get wacked good .Turned out previous owner had run some lights from the kitchen ring, not fused etc . Poor quality fitting that started to have problems once the rubbish decking rotted away ! He presumed they where all on the same circuit !

 

[mainline]

I am way to OCD . I tend to wipe out the whole board if possible when dealing with issues outside . Ive seen a guy get wacked good .Turned out previous owner had run some lights from the kitchen ring, not fused etc . Poor quality fitting that started to have problems once the rubbish decking rotted away ! He presumed they where all on the same circuit !

I'm basically the same when it comes to metal and outside lights, especially since that young boy died due to a pub's garden lamp post being live.

 

[TerryB NZ]

A voltstick wouldn't have helped in this case because the circuit was already known to be live, maybe an old type neon screwdriver would have alerted you but if it was water in the bottom that got tipped around internally when you grabbed it then it also might not have tested live before you moved it.

An RCD also isn't protection against shock, it doesn't even reduce the shock at all it only limits the duration. It's going to trip in 40mS but in that time you will still receive 4 pulses of over 300 Volts peak voltage which is way more than enough to put you on your a$$.

Working with gloves on would have helped to some degree. Something else that would help if you keep one hand in your pocket the old fashioned way is LV dielectric shoes to EN20345 sometimes called ESR or EH rated. They're not like the HV linesmans wellington type boots, they look like normal sneaker shoes and I'm not sure why these haven't caught on in the UK. Come to think of it I can't remember them ever even being mentioned on the forum. Might be time to add a pair to your wish list.

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Little bit off track, but I wear Dewalt work boots that are supposed to be electrically insulated according to the box.
So one day I’m out with a mate clearing a fallen tree from a 4 wire fence with two hot wires. Do the old touch test, first with a piece of grass, then tap with my hand and nothing.
I grabbed the wire and started to get over the fence.
Half way over my hand pushing the hot wire down touched another wire that was not insulated to ground and wack!
I jumped slipped and fell down the bank on the other side and swore like a sailor.
My mate just laughed his arse off.
The fence unit is 10000’s of volts with no current. But the boots obviously work.
So now it’s isolate test and test again.

 

[brianmoooore]

Volt stick always goes in before I do, but in this case there's a possibility that the fitting wasn't live at all until it was picked up and its wiring disturbed.

 

[nicebutdim]

If nothing else this thread gives us all something to think about. Might shake a bit of complacency and prevent a potential belt or two.

 

[LukeD]

Volt stick always goes in before I do, but in this case there's a possibility that the fitting wasn't live at all until it was picked up and its wiring disturbed.

Me too....... They stay with at all times on a job

 

[Marvo]

Problem with a volt stick is if you put it near a spike light that you know has power on it you'd half expect at least that it would give you a live alarm even if the fitting casing was safe. The old neon screwdriver would give a more accurate result although even that wouldn't help if the outer casing only became live when it was moved.

Also as already mentioned there's a possibility that the 2 faults ie the CPC becoming disconnected and the now floating CPC wire coming into contact with supply voltage actually occurred in another fitting on the same circuit possibly some distance away so no amount of visual inspection would have helped either.

The only 2 ways I can see to mitigate the risk in this specific instance is either to isolate before touching or assume it's live and mitigate shock risk by having effective PPE like dielectric footware and gloves. Both of these measures would never be expected of the user of the installation so I guess it would be unreasonable to expect it of an electrician who's not doing anything that a everyday person wouldn't do.

We all know that we'd probably also have suffered the same outcome in this scenario because we'd probably have considered that the belt and braces approach of having a CPC along with the internal insulation resistance of wiring and components would protect us. The third thing that might have helped would be parallel earth paths providing sufficient current flow to cause the OCPD to disconnect but that obviously also didn't happen. The more I think about it the more it sounds like a scene from those movies where death goes looking for people who should have died in a plane crash but they managed to avoid it and they all start dying in very convoluted circumstances....

 

[mainline]

The problem with having insulated boots, gloves etc is that you could leave something that could kill someone else.

The only real way would have been to check that at least there was a working rcd.

I'm not knocking the O/P at all, as it's quite easily done.

A volt stick won't usually work when an L conductor is surrounded by metal, such as the metal light fitting.

Maybe the O/P will come back and let us know what the actual issue was.

 

[SparkySy]

These are pretty useful testers, I carry one in my kit and it's saved me a fair few times!
kewtech KT1700

https://isswww.co.uk/kewtech-kt1700-single-pole-voltage-tester?gad_source=1&gclid=Cj0KCQjwzva1BhD3ARIsADQuPnVkDLyExSFEZmQrFmcpnDsEjsdbRqwCmaovPHZVjOUrZ1SV6BQm1PsaAp8OEALw_wcB

Much more reliable than a voltstick.
I carry a couple of voltsticks, one fluke one which I rate more than the other one I carry kewtech duo. Bought this after being impressed by the KT1700.
The fluke voltage range is from 200v and not over sensitive.
The duo is from 90v and will tell you just about every wire is live!

The KT1700 has even found cut outs that have phenolic degradation that would have not been good if the seal fairy had been and I had gone to remove them!

 

[brianmoooore]

Problem with a volt stick is if you put it near a spike light that you know has power on it you'd half expect at least that it would give you a live alarm even if the fitting casing was safe.

Possibly, but if I see that thing light up red, then I'm on my guard, and move it around a bit. If it still lights when close to a metal spike, then I'm not going to grab hold of that spike without checking further.

 

[JosephandAmber]

So, I'm still not 100% sure what caused the shock. I did find a CPC that had pretty much corroded out of the terminal block it was supposed to be in. Most of the JBs and lights had water ingress. I suspect a water-filled light created an L-E fault, but the disconnected CPC meant it was not tripping the breaker. Still, though, this doesn't explain why it tripped when it came to me being shocked. I ended up ripping most of it out, and yes, it is now on an RCBO until they upgrade the CU.

I would also suggest to everyone installing garden lights that whilst the flexible metal conduit looks the part, pretty much every run I found within this installation was full of water. If you're going to use a conduit use plastic slot conduit that allows water to drain out.

I've also decided to make some purchases off the back of this and I would suggest that anyone reading this takes note:

Kewtech KT1700 Single Pole Voltage Tester

https://www.amazon.co.uk/dp/B009K2E5MI?ref=ppx_yo2ov_dt_b_fed_asin_title

From now on, I will use this on any metal fixing before I touch it.

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Or

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Yes, they're pretty ugly but if it stops me getting killed then it's worth it.



If anyone has any other recommendations, then fire away! We can all learn from this.

 

[mainline]

One of the things I can think of is to not use mains powered outside garden lights but to use the selv type.

 

[JosephandAmber]

One of the things I can think of is to not use mains powered outside garden lights but to use the selv type.

I want to agree, but the moment you introduce transformers in a garden environment, you are adding additional points of failure and cost.

 

[mainline]

I want to agree, but the moment you introduce transformers in a garden environment, you are adding additional points of failure and cost.

The transformer can be inside.

 

[DPG]

The transformer can be inside.

As long as volt drop doesn't become a problem.

 

[brianmoooore]

VD only becomes a problem if the design of the circuit is poor and the size of the cables inadequate.

 

[DPG]

VD only becomes a problem if the design of the circuit is poor and the size of the cables inadequate.

Well yes obviously, but if the transformer is indoors and your lights are 50m down the garden then it's very easy to need pretty big cables at 12V. It's fundamentally a bigger problem than when using 240V.