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Comment by pvitz | Hacker News Reader

This happened to me as a young teenager. I tried to figure out which part of the power supply was broken. The case was opened, I measured some parts, connected it, turned it on and tested if it was working again and disconnected it before continuing to work. After the fourth time, I forgot to disconnect it before touching something with both hands. Fortunately, the GFCI was working as intended, but the cramp in my arms and a very strange feeling around my heart is something I will never forget.

So, to add another advice, be sure that you have a ground fault circuit interrupter or residual-current device and test it regularly.

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Question for any medical professionals around: If you experience a substantial electrical shock, but it didn’t cause you to go into cardiac arrest and you don’t have any severe burns, is it likely that the danger is over? Or should you still seek medical attention as soon as possible?

I’m not a medical person but I am an electrician.

If you receive a shock, if can affect the rhythm of your heart and cause problems later. We’re taught to go and get an ECG after receiving a shock. Like jump in the car and go to the doctor or hospital and have someone else drive you. If you’ve received a shock - go get checked out.

Are you part of a union, and is this recommendation feasible because of "worker's compensation"? I imagine I might not go get checked out if I felt like the risk was low enough and I was worried enough about being able to pay the bill.

I received some electrical safety training even though I'm a software engineer and was told the same thing. An electric shock can lead to cardiac arrest for hours after it happened, with no prior warning. You should always see a cardiologist even if you feel completely fine. Without an ECG you can't know the risk.

>An electric shock can lead to cardiac arrest for hours after it happened, with no prior warning.

That's common in the way shark bites and lightening strikes are common. Dropping dead hours after a minor electrical shock is so rare you shouldn't even be worrying about it.

>You should always see a cardiologist even if you feel completely fine.

It was included in your training so the company could cover its ass. By including a comically over the top warning and recommendation like that they are ensuring that statistically nobody will follow the training and the company will have leverage if you get hurt on their watch and sue.

It's a really shame that this kind of disingenuous ass covering behavior gets picked up and parroted by people as though it were honest advice because it moves the overton window and leads to a world where everyone acts like step-stools are a serious threat to public health.

A friend who still works at that company has seen two minor electrical accidents during his career so far. An ambulance was naturally called and copious amounts of paperwork filled out. Workplace procedures were adapted so that such accidents will be less likely in the future.

Everybody follows the training, because you get fired if you don't, or your manager gets fired. I don't know where you live, but here we have unions that make sure workers are as safe as reasonably possible.

It is certainly a known fact that electrical shock can lead to death even hours after the event occured, which is why there is a legal requirement in most industrial nations with a working healthcare system that you get yourself checked even if you are feeling good.

Your heart muscle is controlled by a tiny voltage. Suddenly forcing it to follow 50/60Hz of a huge voltage isn't precisely natural, and something that can leave lasting damage even if your heart seems to work just fine immidiately after.

There is a reason in electrics a lot is done just to prevent electrical shocks (e.g. RCDs), because you know: it kills people.

I am legally allowed to connect houses to the electrical grid in Germany.

I have experienced some shocks from ground loops, where the shock was only perceptible when the current density was small enough. If I placed my whole palm on the conductor, I couldn't feel it, but if I placed just my finger tip on the edge, I could.

That was an electrical shock that in my naive opinion does not pose a cardiac risk.

I imagine that there is some judgement call to make about what is "electrical shock", and when does it pose a cardiac risk.

If all is going well, shocks are rare, and so I could imagine as a rule "if you felt a shock, go to the doctor". But in some [yes, of course, unfortunate, avoidable, and unacceptable] contexts, a rule like that might not be followed. That is why I was wondering about what guidance electrician's unions provide.

I am sorry for you if you live in a country where you have to chose between paying the bills or making sure you won’t end up in cardiac arrest because of something that happens as a part of your job. It hasn’t got anything to do with unions, it is basic respect for human life.

Thanks, I'm sorry too!

"basic respect for human life" and "unions" can have a lot in common, especially in such a country.

If it is not inconvenient I would at least call your doctor - there have been cases (involving very high voltage equipment to be sure) where no outward damage was seen but some internal was done.

For normal household circuits I’d just say learn from your mistake.

A huge number of regular household objects are more than capable of killing you with the voltage they're capable of exposing. Go to A&E. The risk being low isn't the issue, it that the consequence if it's a problem and you don't get it checked out is: you die.

Think of it as an inverse lottery you really really don't want to lose. The outcome, not the odds is what matters in this case.

Am medical professional, if you receive a substantial electrical shock you should seek medical attention ASAP. There is the potential for a lethal arrhythmia to evolve even if you feel relatively fine immediately afterward.

Quite. And the time period for changes to evolve is comparatively long -- up to 12 hours -- if the heart muscle is damaged and a scar forms later on, leading to the potential for life-threatening arrhythmias. Bradycardia is also sometimes reported long after the event. On top of that, there are reported "cTNI +ve without pain" events indicating significant cardiac injury detected only via ECG or blood tests (for cardiac troponin).

A very good summary article is here: https://www.bmj.com/content/357/bmj.j1418 .

Take home points:

-- Arrhythmias (superventricular and ventricular) are common

-- Exposure to high voltage can cause asystole directly

-- Delayed [life threatening!] ventricular arrhythmias have been reported for up to 12 hours post incident, both with high and low voltage shocks

-- Delayed, serious bradycardia can result months or years after the accident

-- The SA nodes are particularly vulnerable; patients may effectively give themselves an SA node ablation

-- Direct myocardial injury may occur without chest pain (due to nerve damage)

-- MI may also occur via coronary spasm or thrombus.

That neglects the rest of the body -- where the effects can also be significant.

Electricity in large amounts is bad for you – c.f. the electric chair!

> Exposure to high voltage can cause asystole directly

Yep. This is what defibrillation is. When you use a defibrillator, you're shocking the heart into asystole in the hopes that it will restart itself. Shocking an already "flatlined" heart will not restart it, contrary to what many movies would have you believe.

> The SA nodes are particularly vulnerable; patients may effectively give themselves an SA node ablation

This I did not know. Wow!

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