4 ms·

Let me add, (from experience) that any way the plug gets lit, whether it be old school distributor, coil pack, or coil on plug, it can shock a human very badly.

Let me add, (from experience) that any way the plug gets lit, whether it be old school distributor, coil pack, or coil on plug, it can shock a human very badly. It's easy to get lulled into a false sense of comfort working on 12v automotive electricals, but the power levels going to the spark plug are much higher.

technothrasher 2y ago
I build and sell reproduction electronic ignition units for old 1980s sports cars, and I've gotten hit with the full secondary voltage on my bench setup a couple times. Even with current limiting and safety cut-outs in place on my bench top power supply, it is very, very unpleasant.
xeromal 2y ago
Don't those coil packs distribute 10-20k volts?
londons_explore 2y ago
I'm kinda sad that as far as I can see, no cars have protections against 'stupid DIY mechanic puts finger in spark plug while cranking engine'. I'm sure those sparks have killed many people by now. All they'd need to do is have the spark happen not to ground but to another return wire, and then check the impedance between both wires and ground is infinite before firing. Plenty of other benefits to such a design - eg. you can more accurately measure flame propogation within the cylinder (detect bad nozzles on injectors).
- MisterTea 2y ago
  > I'm sure those sparks have killed many people by now. Probably not many. I have been shocked when I was twisting the distributor on my old '95 Tahoe to adjust timing after maintenance. It bit me good but I have felt and survived worse.
  - londons_explore 2y ago
    Those who don't survive don't post on HN
    - MisterTea 2y ago
      I never heard of them killing anyone. Though I am sure the resulting shock might be enough to trigger issues in those with weak hearts or injury resulting from pulling away rapidly where a fall or slip can cause a severe injury.
    - talldatethrow 2y ago
      Most of my social circle is people that do custom crazy stuff with things with engines. 1000hp off-road trucks, jetskiis that do backflips, cars into the 9 second quarter mile, basically all installation and repair work done by the enthusiast themselves. I know several people that have lost fingers. Two that have lost teeth. Two that have died along crashes. Getting shocked by ignition systems is on par with stubbing your toe.
- _yb2s 2y ago
  I’ve worked as a mechanic and been hit by it before… I don’t think it’s as dangerous as you’d expect from the voltage. I think both the duration of spark, and current are very low.
  - northwest65 2y ago
    At one of my first jobs, the workshop foreman would sidle up beside another mechanic who was working under the bonnet, casually put his arm on their shoulder or whatever, then touch a plug. It would make the other mechanic jump, but he himself seemed impervious (well steeled more like) to the effect.
- AngryData 2y ago
  Ive never heard of anybody ever dieing from it, although I could see it happening in freak cases. If I had a pace maker I might be a little more careful but the only real risk I consider from it is a lot of pain and a tiny arc burn where there was electrical contact. If you are dumb enough to purposefully stick your finger in a spark plug hole and crank the engine though I think that is on you. You shouldn't have your hands in the engine compartment at all when cranking a motor unless you are an expert already.
chasd00 2y ago
i have a vague memory of either my dad or grandfather working on a car and holding on to a sparkplug to see if it not firing was the cause of the problem. I remember them dropping it and shaking their hands like they touched something hot and saying "no, that's not it" hah.

technothrasher 2y ago

I build and sell reproduction electronic ignition units for old 1980s sports cars, and I've gotten hit with the full secondary voltage on my bench setup a couple times. Even with current limiting and safety cut-outs in place on my bench top power supply, it is very, very unpleasant.

xeromal 2y ago

Don't those coil packs distribute 10-20k volts?

londons_explore 2y ago

I'm kinda sad that as far as I can see, no cars have protections against 'stupid DIY mechanic puts finger in spark plug while cranking engine'. I'm sure those sparks have killed many people by now. All they'd need to do is have the spark happen not to ground but to another return wire, and then check the impedance between both wires and ground is infinite before firing. Plenty of other benefits to such a design - eg. you can more accurately measure flame propogation within the cylinder (detect bad nozzles on injectors).

MisterTea 2y ago
> I'm sure those sparks have killed many people by now. Probably not many. I have been shocked when I was twisting the distributor on my old '95 Tahoe to adjust timing after maintenance. It bit me good but I have felt and survived worse.
- londons_explore 2y ago
  Those who don't survive don't post on HN
  - MisterTea 2y ago
    I never heard of them killing anyone. Though I am sure the resulting shock might be enough to trigger issues in those with weak hearts or injury resulting from pulling away rapidly where a fall or slip can cause a severe injury.
  - talldatethrow 2y ago
    Most of my social circle is people that do custom crazy stuff with things with engines. 1000hp off-road trucks, jetskiis that do backflips, cars into the 9 second quarter mile, basically all installation and repair work done by the enthusiast themselves. I know several people that have lost fingers. Two that have lost teeth. Two that have died along crashes. Getting shocked by ignition systems is on par with stubbing your toe.
_yb2s 2y ago
I’ve worked as a mechanic and been hit by it before… I don’t think it’s as dangerous as you’d expect from the voltage. I think both the duration of spark, and current are very low.
- northwest65 2y ago
  At one of my first jobs, the workshop foreman would sidle up beside another mechanic who was working under the bonnet, casually put his arm on their shoulder or whatever, then touch a plug. It would make the other mechanic jump, but he himself seemed impervious (well steeled more like) to the effect.
AngryData 2y ago
Ive never heard of anybody ever dieing from it, although I could see it happening in freak cases. If I had a pace maker I might be a little more careful but the only real risk I consider from it is a lot of pain and a tiny arc burn where there was electrical contact. If you are dumb enough to purposefully stick your finger in a spark plug hole and crank the engine though I think that is on you. You shouldn't have your hands in the engine compartment at all when cranking a motor unless you are an expert already.

chasd00 2y ago

i have a vague memory of either my dad or grandfather working on a car and holding on to a sparkplug to see if it not firing was the cause of the problem. I remember them dropping it and shaking their hands like they touched something hot and saying "no, that's not it" hah.