Today I experienced the worst electric shock my career

[JosephandAmber]

Today, I experienced the most severe electrical shock of my career. Fortunately, I'm here to write about it. I've been replaying the situation in my mind, analysing what I could have done differently to prevent it. The most crucial takeaway is this: ALWAYS ASSUME ALL EXTERNAL METAL LIGHTS ARE LIVE UNTIL PROVEN OTHERWISE.

Here's what happened:

The customer has garden lighting with GU10 spike lights, some of which weren't functioning and showed visible signs of water ingress. We went outside, and I asked the customer to turn the lights on to identify which ones were still working. She switched them on, and a few of the GU10s lit up. The customer then asked what I would replace them with, so I opened a box containing a new GU10 spike light. She noticed the spike seemed a bit short, and I explained that I could order extensions or possibly reuse the spikes from her existing lights. To demonstrate, I picked up one of the existing GU10 spike lights that was functioning and showed no visible signs of water ingress. As I reached out to grab the spike to unscrew it, I suddenly became part of the circuit. My hand immediately clamped around the light, and I was paralysed by the shock. I distinctly remember feeling utterly helpless as the current surged through my body. I let out a terrible scream and collapsed towards the ground. I'm not sure how long I was in contact with the light, but it felt like several seconds. Suddenly, the power cut off, and I was able to release my grip. I turned pale, and the customer was utterly shocked.

After sitting down and ensuring I was okay, I went to inspect the RCD, which I believed had saved my life. To my surprise, the only circuit that had tripped was a non-RCD protected 10Amp Type B MCB. I had tripped the overcurrent device!

I suspect that as I fell towards the ground, the light made contact with the soil, allowing enough fault current to flow, perhaps?

I felt both embarrassed and angry that the circuit wasn't RCD protected.

To my fellow electricians: was I an idiot for not checking the light first, or would you have done the same in this situation?

 

[James]

Wow, I do like an honest replay of our own failures.
I have posted a few myself and although at times it may seem embarrassing, i think it helps people to understand the pit falls and hopefully prevent someone doing what I did.

to be fare, I would probably have done something similar and checked a couple of lights to see how they were wired and what the chance of replacing or otherwise fixing them might be.

in retrospect, the correct thing to do would be to isolate the circuit, IR test it and keep removing things until it becomes safe.
but a first check of what circuit it is fed from would have helped.
a simple, turn the lights on followed by switching breakers off would have told you that the lights were not rcd protected.

don't be embarrassed, hold your head up high and say, I have made a mistake and I want others to learn from it because I know I have!!!

 

[mainline]

I always keep a volt stick on me not the be all but better than nothing

 

[7029 dave]

I always keep a volt stick on me not the be all but better than nothing

they do the job

 

[JosephandAmber]

they do the job

So the ironic thing is I had a touch volt stick on me and I used it to confirm power was live to the cable. I didn’t touch the casing of the light because to be honest sometimes you get a positive reading simply because the internals are energised. I feel like using an actual volt meter would have been the only real way to tell.

As a minimum I’d say always touch with the back of your hand first, but clearly I should have confirmed no RCD first and then treated it with far more caution.

I’ll be honest, I’m also pretty confused about how I managed to trip a 10A MCB using my body!?

 

[davesparks]

I’ll be honest, I’m also pretty confused about how I managed to trip a 10A MCB using my body!?

You didn't, you'd be a burned mess if that much power flowed through your body.

Something else must have happened to cause the MCB to operate.
For the metal case to become live the earth connection must have become disconnected from it and the live become connected to the case.
Most likely is that those two loose connections made contact and caused the MCB to operate.

 

[JosephandAmber]

You didn't, you'd be a burned mess if that much power flowed through your body.

Something else must have happened to cause the MCB to operate.
For the metal case to become live the earth connection must have become disconnected from it and the live become connected to the case.
Most likely is that those two loose connections made contact and caused the MCB to operate.

So when I eventually took the Wiska box apart all connections were sound, albeit damp. I’m planning on returning to do a full circuit breakdown and test. I did a few IR tests in the underground cables and they all failed.

I’m still baffled as to exactly what happened. All I know if that I’m very lucky. After the shock and the insane heat today I called it a day.

 

[HappyHippyDad]

Just having a quick look on the net.
Minimum let go current levels are 6 - 10 mA
Max let go threshold (for 99% of us) is 22mA

I'm assuming the shock you got was from the water ingress around the live terminals which had caused a pathway to the metal spike.

Did you have a seizure or become unconscious?

I think you were unbelievably lucky that a 10A mcb tripped, which, as Davesparks said would have been for a different reason. Without that, your hand would have been a burnt mess and that would have been best case scenario.

Watch out for any after effects and see your GP if you have any.

I'm glad you are alive chap.

 

[timhoward]

I appreciate threads like this. Thanks for sharing and I’m glad you are ok.

The chances are that if it was a pre work discussion about the products I’d have done exactly what you did.

Obviously an RCD would have made this nicer for you or possibly prevented it remaining energised in the first place.

But it’s also a little bit of a red herring (at least until you get as far as contemplate working on the circuit) as even if present it shouldn’t be relied upon to actually work, and we shouldn’t be thinking ‘it’s got an rcd so it’s safe to dive in with both feet’.

I think the main reminders here are
1 - we should treat anything with exposed conductive parts (especially outside) with deep suspicion.
2 - we should not get sloppy about isolating things before we work on them
3 - we should not under estimate the importance of testing a circuit before working on it.

On the plus side the customer got the best possible demonstration as to why they need a new CU and I hope they will now get one.

 

[littlespark]

with any luck, the shock you experienced was a lot less than 10A (had to be, or as it’s put on another thread… You’de be “cooked” by now)

Live conductor, a lot of resistance through dampness to the cpc in the wiska… cpc not continuous back to MET

I’m surprised no one else in the customers household got a shock first… like a dog cocking its leg against the lights.


Something to be said for 12V lighting in a garden with an IP rated power supply.

 

[timhoward]

Something to be said for 12V lighting in a garden with an IP rated power supply.

An excellent point. I’ve modified some to be 12v in a garden that it wasn’t practical to rewire - there are ES and GU10 adaptors to accept GU5.3 lamps. You just have to watch volt drop with 12v on longer runs.

 

[Rockingit]

Wow - glad you're able to tell the tale.

I had something along the same lines happen to me years ago in a marquee : bunch of pre-made brass bc pendants had been strung around the roof of a large banqueting marquee in a sort of festoon style. Got energised and nothing happened. So up I went on a set of 14 rung steps to the first one just to check the basics of plugging in, all was fine. Took it out of circuit and down to the ground to fiddle with..plugged into a temp distro rack and still dead... brushed the metal rack strip of the distro and all of a sudden got one hell of a whack until the RCBO went. Turned out when I opened it up that some total F*Whits in a workshop had wired them all L to brass CPC. I'd been saved on the ladder and the ground basically by the wooden boarding of the floor, never felt even a tingle until a proper return path came into the system.

 

[Marvo]

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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[Penguin]

Today, I experienced the most severe electrical shock of my career. Fortunately, I'm here to write about it. I've been replaying the situation in my mind, analysing what I could have done differently to prevent it. The most crucial takeaway is this: ALWAYS ASSUME ALL EXTERNAL METAL LIGHTS ARE LIVE UNTIL PROVEN OTHERWISE.

Here's what happened:

The customer has garden lighting with GU10 spike lights, some of which weren't functioning and showed visible signs of water ingress. We went outside, and I asked the customer to turn the lights on to identify which ones were still working. She switched them on, and a few of the GU10s lit up. The customer then asked what I would replace them with, so I opened a box containing a new GU10 spike light. She noticed the spike seemed a bit short, and I explained that I could order extensions or possibly reuse the spikes from her existing lights. To demonstrate, I picked up one of the existing GU10 spike lights that was functioning and showed no visible signs of water ingress. As I reached out to grab the spike to unscrew it, I suddenly became part of the circuit. My hand immediately clamped around the light, and I was paralysed by the shock. I distinctly remember feeling utterly helpless as the current surged through my body. I let out a terrible scream and collapsed towards the ground. I'm not sure how long I was in contact with the light, but it felt like several seconds. Suddenly, the power cut off, and I was able to release my grip. I turned pale, and the customer was utterly shocked.

After sitting down and ensuring I was okay, I went to inspect the RCD, which I believed had saved my life. To my surprise, the only circuit that had tripped was a non-RCD protected 10Amp Type B MCB. I had tripped the overcurrent device!

I suspect that as I fell towards the ground, the light made contact with the soil, allowing enough fault current to flow, perhaps?

I felt both embarrassed and angry that the circuit wasn't RCD protected.

To my fellow electricians: was I an idiot for not checking the light first, or would you have done the same in this situation?

 

[Penguin]

We’ve all been there, at one point it another.!
Firstly if always check the circuit protective device.
And if worst comes to worst always go up to a metal device with the Back of your hand…!!
But technically get the FLuKE out first and do the checks for the board, it first outlet.

Good luck.

 

[mainline]

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.

Electrical Insulated (1000volt) Safety Trainer SB FO WRU HRO SRC - Enduro

Electrical Insulated (1000volt) Safety Trainer

enduro.co.uk

ROBUSTA FORMIO DIELECTRIC BOOTS - Sparks Workwear Ltd | Online Store

Electrically Insulating technical footwear from Spanish brand Robusta TECHNICAL INFORMATION

sparksworkwear.com

C99H-ISOL47 | Penta Unisex Ankle Safety Boots, UK 12, EU 47 | RS

za.rs-online.com

He said it didnt show signs of water ingress and that he got the shock when he grabbed it.
A decent volt stick especially one you are used too would more than likely have shown the metal to be live.

Certainly a decent 2 pole tester would have.

It maybe that there wasn’t a problem with this particular one, it may have been another that had the ingress and was causing the interconnected cpc to go high.

Lesson is if the circuit is energised then check the metal isn’t.

 

[littlespark]

trouble is with a 2 pole tester... youve got to touch the fitting to remove the cover to access the connectors.

no one would think that a light, which is working, and you havent been told already someone got a shock off it.... would have a live casing.

Its easy to say in hindsight that it should have been checked before going anywhere near it.... but accidents happen... and it could have been way worse

 

[JosephandAmber]

I'm glad most of you think I got very unlucky with this one. It's absolutely a lesson learned, but at the same time, I don't feel like I did anything that was seriously bad practice. I cannot believe how lucky I was that the breaker tripped. Being shocked and knowing you cannot let go is seriously scary. I've had minor shocks before (haven't we all) but never one where I was at the complete mercy of a protective device tripping.

 

[nicebutdim]

I'm glad most of you think I got very unlucky with this one. It's absolutely a lesson learned, but at the same time, I don't feel like I did anything that was seriously bad practice. I cannot believe how lucky I was that the breaker tripped. Being shocked and knowing you cannot let go is seriously scary. I've had minor shocks before (haven't we all) but never one where I was at the complete mercy of a protective device tripping.

You didn't do anything a homeowner wouldn't be expected to do, much less the average electrician.

 

[SparkySy]

It sounds like you were very unfortunate to get a shock but lucky that the device tripped and saved you!
And as @nicebutdim says, it's lucky the householder hasn't been a victim of its fault.

Many years ago when I had just finished my apprenticeship I managed to get a huge belt off an immersion heater that was on economy 10 so received random boosts during the day.
It taught me to be incredibly wary with anything metal cased as a result!

 

[mainline]

trouble is with a 2 pole tester... youve got to touch the fitting to remove the cover to access the connectors.

no one would think that a light, which is working, and you havent been told already someone got a shock off it.... would have a live casing.

Its easy to say in hindsight that it should have been checked before going anywhere near it.... but accidents happen... and it could have been way worse

Why would you have to access the connectors ??

 

[davesparks]

A decent volt stick especially one you are used too would more than likely have shown the metal to be live.

It would certainly have made you wary of it.

Certainly a decent 2 pole tester would have.

Only if you had somewhere to put the second probe.

 

[davesparks]

Why would you have to access the connectors ??

To find two points to put your 2 probes on.

 

[mainline]

To find two points to put your 2 probes on.

He would have a decent ground very nearby, ie himself, otherwise he wouldn't have got a shock in the first place.

A decent 2 probe voltage tester like a Fluke 150 will detect L using one probe.

 

[davesparks]

He would have a decent ground very nearby, ie himself, otherwise he wouldn't have got a shock in the first place.

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