Author Topic: How I almost killed myself  (Read 18274 times)

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Offline TNbTopic starter

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How I almost killed myself
« on: October 01, 2016, 10:00:14 pm »
Well, I don't know why I am writing this, maybe to remind others about safety, but you can just feel free to laugh and write "what an idiot you are" below.

So I came back home from a walk and my feet were tired of walking in crappy shoes, so I decided to take "feet bath", don't know how to call it in English, basically put your feet in a bowl with hot water to relax. While taking the bath I was repairing some crap with a glue gun. You guessed right. So I put the glue gun on the table to fiddle around with other crap, then bam - glue gun, turned on into 220 V mains falls off the table to the bowl of water where my feet are. Who knows for what reason, but nothing happened - circuit breaker is not turned off, I am not electrocuted, I just pull out my feet and glue gun out of the mains socket.
Have no idea why nothing happened, because that glue gun is absolute cheapest chinese crap, I wonder if it is so well insulated inside, if it is - I would like to send some thankful money to engineer who designed it.

So the moral of the story - don't be a fucking idiot and don't do stupid shit like that, safety first and so on. But really, even very experienced people like to screw safety, seen many factory workers just spitting on every safety aspect. Don't be those guys, and don't be like me for certain.

And while we are at it, if somebody has time to answer some related questions it would be nice:
1) It seems I don't have residual current device(at least I don't see it in this appartment), but if I would have it - does it save from this kind of shit? I guess not, since I am basically in the middle of the circuit or something... don't know much about RCD, would be interesting to know.
2) How the hell it didn't do anything? Is it insulation? How can such a good insulation be in glue gun? Let alone 1$ shit like this. I can do a teardown probably, not now though, too tired.
 
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Offline mikeselectricstuff

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Re: How I almost killed myself
« Reply #1 on: October 01, 2016, 10:03:15 pm »
What was the bowl made of ?
if plastic, then you could probably stick 240V live in the water and unless another part of you had a path to ground you wouldn't feel a thing.
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Offline TNbTopic starter

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Re: How I almost killed myself
« Reply #2 on: October 01, 2016, 10:04:41 pm »
It is plastic, but glue gun has both live and neutral wire in it, isn't it enough to conduct through water? I mean, at least I would feel something, no?
 

Offline mikeselectricstuff

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Re: How I almost killed myself
« Reply #3 on: October 01, 2016, 10:17:08 pm »
It is plastic, but glue gun has both live and neutral wire in it, isn't it enough to conduct through water? I mean, at least I would feel something, no?
Only if a part of you was between the live and the neutral
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Offline TNbTopic starter

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Re: How I almost killed myself
« Reply #4 on: October 01, 2016, 10:19:58 pm »
It is plastic, but glue gun has both live and neutral wire in it, isn't it enough to conduct through water? I mean, at least I would feel something, no?
Only if a part of you was between the live and the neutral
But my feet are technically in between, though of course the resistance and distance is much greater than from leads themselves.
If all that is not so dangerous - how is there so many stories about people killing themselves in a bathtubs with a hairdryer?
 

Offline RGB255_0_0

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Re: How I almost killed myself
« Reply #5 on: October 01, 2016, 10:23:03 pm »
Electroboom has a video basically explaining the same thing, but with his finger. With Live and Neutral so close, and you not providing a path (being in parallel) you were fine. May have been different if you touched something with a path to ground/neutral, though!

Your toaster just set fire to an African child over TCP.
 

Offline TNbTopic starter

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Re: How I almost killed myself
« Reply #6 on: October 01, 2016, 10:32:59 pm »
Electroboom has a video basically explaining the same thing, but with his finger. With Live and Neutral so close, and you not providing a path (being in parallel) you were fine. May have been different if you touched something with a path to ground/neutral, though!


Oh, interesting, thanks!
I guess all those stories about people committing suicide in bath with hairdryer are myths, unless they are touching grounded tubes.
Anyway, I am not going to repeat the experiment :D
 

Online IanB

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Re: How I almost killed myself
« Reply #7 on: October 01, 2016, 10:48:30 pm »
A bath is completely different from the bowl.

A bath usually has any metal parts like taps bonded to earth, so mains current has a path through the water (and potentially through you) to ground. If you get between a live wire and a path to ground then you could be electrocuted.

Your plastic bowl was insulated from earth and there was no path to ground through your body (unless you were to touch something metal while your feet were connected to mains).

 

Offline helius

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Re: How I almost killed myself
« Reply #8 on: October 01, 2016, 10:55:35 pm »
Unless the water contained salts, its resistance was higher than the heater in the glue gun. Also consider the spatial distribution of current within the bowl: it will be highest in the immediate vicinity of the input wires, and lower with increasing distance.
Electrocution in bathtubs is much more likely when there are grounded fittings in contact with the water (like brass drains). There is then a path from the live wires to ground that passes around a bathing person. The danger is even higher if they are lying in the water along the same direction as that path: because voltage difference across the body is what causes current to flow inside the body. If they touch the grounded fitting it is even worse.
 

Offline TNbTopic starter

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Re: How I almost killed myself
« Reply #9 on: October 01, 2016, 11:01:57 pm »
What about residual current device? Does it help if person in a bathtub with a hairdryer?
 

Offline RGB255_0_0

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Re: How I almost killed myself
« Reply #10 on: October 01, 2016, 11:05:04 pm »
RCD would only help if current was going back via the protective earth/other than the neutral and exceeded the leakage rating. RCD wouldn't protect you if you stuck your hand in an insulated bowl powered by a 2-wire mains device and you were isolated also.

Again there are videos about this on YouTube.
« Last Edit: October 01, 2016, 11:07:13 pm by RGB255_0_0 »
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Online IanB

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Re: How I almost killed myself
« Reply #11 on: October 01, 2016, 11:06:14 pm »
What about residual current device? Does it help if person in a bathtub with a hairdryer?

It should do. However, if you were in the UK you would have nowhere to plug in the hairdryer close to the bath, so the combination of hairdryer and bath would be very unlikely.
 

Offline edpalmer42

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Re: How I almost killed myself
« Reply #12 on: October 01, 2016, 11:11:12 pm »
Can we see a teardown of the glue gun?  If they used heatshrink to insulate the electrical connections, there might not have been any electrical connection between the water and the power.

Mythbusters investigated this idea and found that you can definitely get killed this way.  Remember that their tests were done with 110 VAC.  You'd be twice as dead at 220 V!  ;)

Are there any countries where there must be a ground connection to a bathtub?  In North America, all the pipes are now plastic and the tubs are plastic, so there might not be a ground to trigger our GFCIs.  With a two wire appliance, you could easily die.

Ed
 

Online IanB

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Re: How I almost killed myself
« Reply #13 on: October 01, 2016, 11:16:02 pm »
Water pipes should definitely be copper. There have been lawsuits over house floods caused by burst or broken plastic water pipes.
 

Offline RGB255_0_0

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Re: How I almost killed myself
« Reply #14 on: October 01, 2016, 11:18:07 pm »
Pretty sure all new work in the US must now have GFCI and bonding in new installations for basins/baths since at least 2014 because of 2-wire appliances.
Your toaster just set fire to an African child over TCP.
 

Offline TNbTopic starter

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Re: How I almost killed myself
« Reply #15 on: October 01, 2016, 11:18:36 pm »
Can we see a teardown of the glue gun?  If they used heatshrink to insulate the electrical connections, there might not have been any electrical connection between the water and the power.
Tomorrow, it's quite late here, gonna hit the sack soon.
Are there any countries where there must be a ground connection to a bathtub?  In North America, all the pipes are now plastic and the tubs are plastic, so there might not be a ground to trigger our GFCIs.  With a two wire appliance, you could easily die.
In Finland and Russia you can easily find grounded water tubes, I am not sure if this is required by law, but most houses are like that.
 

Offline helius

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Re: How I almost killed myself
« Reply #16 on: October 01, 2016, 11:31:40 pm »
All hairdryers in the US have GFIs built into their cords. They should have a ground wire in the cord even if there is none in the electric outlet, so they should still trigger if dropped into a bathtub. Filling the bathtub with DI water might prevent that.
 

Offline amyk

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Re: How I almost killed myself
« Reply #17 on: October 02, 2016, 12:23:12 am »
I'd say you were very far from killing yourself as the current would've far preferred to go through the heater or the water immediately surrounding the wires than through the water, you, and whatever else before it reaches ground. Unless the water had salts (conductive ions) in it, it would not be very conductive either.

Some more discussion on safety (and perhaps a distorted perception of such) here:
https://www.eevblog.com/forum/projects/suicide-shower-hear-teardown/

tl;dr: electricity can be dangerous but only if a lot of it passes through you... which doesn't happen that often.
 

Offline Red Squirrel

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Re: How I almost killed myself
« Reply #18 on: October 02, 2016, 12:28:45 am »
Path of lease resistance.  I'd say the heat element in the glue gun would be it, even when it's in the water, especially if there was no salt in the water, but if you added salt then it does make it a bit more dangerous.  Basically some current will travel through water and back to gun but most of it will be going through the element.
 

Offline rdl

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Re: How I almost killed myself
« Reply #19 on: October 02, 2016, 12:47:34 am »
These apartments were built around 2001-2002, and all the plumbing that I can see is plastic. Under both the kitchen and bath sinks, about 3" of white PVC comes out of the wall. There's a fitting of some kind on the end where flexible tubing is attached that runs on up to the faucets. I can see down the drain in the tub and it's white plastic also. I can't see the supply there though because it's inside the wall. The pipes to and from the water heater are red and blue plastic.
 

Online IanB

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Re: How I almost killed myself
« Reply #20 on: October 02, 2016, 12:55:00 am »
Yes, plastic definitely gets used for water pipes, but it is a cost cutting measure and is something you should complain about.

If copper pipes fail you tend to get pinhole leaks which can be spotted and repaired while the damage is still localized.

if plastic pipes fail they tend to split or break which will cause a huge amount of water damage if you don't manage to shut the water off immediately. This is especially true of PVC pipes.

My house was originally built with plastic water pipes and they were all replaced with copper piping after a class action lawsuit.
 

Offline Macbeth

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Re: How I almost killed myself
« Reply #21 on: October 02, 2016, 01:31:00 am »
What about residual current device? Does it help if person in a bathtub with a hairdryer?

It should do. However, if you were in the UK you would have nowhere to plug in the hairdryer close to the bath, so the combination of hairdryer and bath would be very unlikely.
This is where you are wrong. I regularly plug in my mains cable extension reel in the hallway and roll it out to the bathroom where I leave it precariously dangling near the taps. My hairdryer will be in one socket and my beard trimmers in the other, or else a bar fire in the winter months that I jam in the corner between the shampoo bottles.  :-DD

I know I'm safe because a proper electrician has rewired the house to BS 7671:2008+A3:2015 (Yes, a metal consumer unit is now mandatory instead of plastic).

I also have all those 99p shop battery chargers and night lights plugged in at all times, the ones Big Clive tears down that seem to go up in smoke.
 

Offline JoeN

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Re: How I almost killed myself
« Reply #22 on: October 02, 2016, 01:57:29 am »
Well, I don't know why I am writing this, maybe to remind others about safety, but you can just feel free to laugh and write "what an idiot you are" below.

So I came back home from a walk and my feet were tired of walking in crappy shoes, so I decided to take "feet bath", don't know how to call it in English, basically put your feet in a bowl with hot water to relax. While taking the bath I was repairing some crap with a glue gun. You guessed right. So I put the glue gun on the table to fiddle around with other crap, then bam - glue gun, turned on into 220 V mains falls off the table to the bowl of water where my feet are. Who knows for what reason, but nothing happened - circuit breaker is not turned off, I am not electrocuted, I just pull out my feet and glue gun out of the mains socket.
Have no idea why nothing happened, because that glue gun is absolute cheapest chinese crap, I wonder if it is so well insulated inside, if it is - I would like to send some thankful money to engineer who designed it.

So the moral of the story - don't be a fucking idiot and don't do stupid shit like that, safety first and so on. But really, even very experienced people like to screw safety, seen many factory workers just spitting on every safety aspect. Don't be those guys, and don't be like me for certain.

And while we are at it, if somebody has time to answer some related questions it would be nice:
1) It seems I don't have residual current device(at least I don't see it in this appartment), but if I would have it - does it save from this kind of shit? I guess not, since I am basically in the middle of the circuit or something... don't know much about RCD, would be interesting to know.
2) How the hell it didn't do anything? Is it insulation? How can such a good insulation be in glue gun? Let alone 1$ shit like this. I can do a teardown probably, not now though, too tired.

Can you describe the circuit that was created that made you part of the circuit and took the mains current through the core of your body?

I can't either.
Have You Been Triggered Today?
 

Offline Brumby

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Re: How I almost killed myself
« Reply #23 on: October 02, 2016, 02:14:01 am »
Yes.

The danger is NOT that voltage is being somewhere ... it is is that current is going somewhere - and that the path it takes goes through your body.  (Only IF it goes through your body does it matter WHERE it goes through your body.)
 

Offline Red Squirrel

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Re: How I almost killed myself
« Reply #24 on: October 02, 2016, 04:18:54 am »
On subject of mistakes, I was just messing around with a 555 timer, trying to figure out the best combination with the parts I have to max it out (it's a 100khz one so trying to at least get close to 100) and I smelled something funny, without thinking, I checked to see if the resistors were hot.  One of them was.  Very very very hot. That left a nice resistor shaped mark on my finger. Going to feel the burn for a while.  :-DD
 


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