Electric shocks, are they dangerous?

[Quandary]

This is not boaty but I respect the quality of technical advice you get here.
When I use my petrol strimmer if my elbow touches the motor I get electric shocks down my arm, just an irritation but is exposure to these dangerous to old folk? I have stripped the thing down checked the plug lead etc. but I am still getting them even in dry conditions.
Back in my youth I cleaned the plugs on my magneto ignition Matchless twin, then took her down the road, she went on to one cylinder, one of the plug leads had come off, I slowed down a bit but when I reached down to put it back the shock straightened my other arm putting her on to full lock and me over the handlebars on to the road. Someone explained the mag. put out 600v. but the little ignition device on the strimmer should be producing less than that?

 

[Seastoke]

This is not boaty but I respect the quality of technical advice you get here.
When I use my petrol strimmer if my elbow touches the motor I get electric shocks down my arm, just an irritation but is exposure to these dangerous to old folk? I have stripped the thing down checked the plug lead etc. but I am still getting them even in dry conditions.
Back in my youth I cleaned the plugs on my magneto ignition Matchless twin, then took her down the road, she went on to one cylinder, one of the plug leads had come off, I slowed down a bit but when I reached down to put it back the shock straightened my other arm putting her on to full lock and me over the handlebars on to the road. Someone explained the mag. put out 600v. but the little ignition device on the strimmer should be producing less than that?

they wont kill you,and will you be taking my ropes tomorrow at the crinan

 

[No Regrets]

I suspect your plug lead or HT has leakage! Might be worth cleaning and spraying with electric contact sealer

 

[savageseadog]

Shocks from a magneto won't kill you, there's not enough energy (or current). It's not a good idea to leave it though because the reflexes might cause someone to lose control of the strimmer, drop it perhaps.

 

[Spirit (of Glenans)]

I suspect your plug lead or HT has leakage! Might be worth cleaning and spraying with electric contact sealer

A quick google suggests that a HT lead carries 35,000v. This is for a car engine, but a strimmer engine would certainly have voltage in the 10s of thousands. Any leakage can be cured by Damp-Start spray, from a motor factors.

 

[earlybird]

It's the amps wot does it, but several Kv isn't recommended. However, wrinklies often have dry skin, which helps.

 

[macd]

Back in my youth I cleaned the plugs on my magneto ignition Matchless twin, then took her down the road, she went on to one cylinder, one of the plug leads had come off, I slowed down a bit but when I reached down to put it back the shock straightened my other arm putting her on to full lock and me over the handlebars on to the road.

I've heard (and given) some dotty excuses for falling off bikes, but that's an absolute beaut. In fact I'm about to pass it on...
Thanks

 

[jwilson]

"It's volts that jolts, but mills that kills".

HT lead may be 20,000-30,000 volts, but pretty low current (far lower than 1 milliamp).

 

[macd]

"It's volts that jolts, but mills that kills".

HT lead may be 20,000-30,000 volts, but pretty low current (far lower than 1 milliamp).

Isn't 50mA or so (across the chest) about the level that becomes dangerous?

 

[pvb]

By all means try squirting some magic spray on it, but a better solution might be to get it fixed. Electric shocks shouldn't be a normal part of strimming!

 

[lw395]

Yes it could be dangerous.
Don't assume it's harmless low current HT.
More likely to be the LT side where there is both volts and current available.
Plus there is spark and petrol risk, and risk of losing control due to electroconvulsion.

 

[Solent sailer]

30mA will kill you hence the requirements for a 30mA rcd on sockets in the UK now. Could what you are getting be static? You have lots of rotating bits and very dry weather.

 

[Quandary]

they wont kill you,and will you be taking my ropes tomorrow at the crinan

What is the name of your boat and I will look out for you at locking in time.
Joe

 

[pvb]

What is the name of your boat and I will look out for you at locking in time.
Joe

Don't do any strimming in the meantime...

 

[elton]

Isn't 50mA or so (across the chest) about the level that becomes dangerous?

Yes, between the hands ("across the chest"). As a TV repair man I was taught to work with one hand in my pocket to prevent this. Though I did prefer to work with both hands in my pockets.

 

[Thistle]

they wont kill you,and will you be taking my ropes tomorrow at the crinan

I've seen someone stopping a 4 cyl truck engine by licking his arm and putting it across the 4 plug tops, something he did regularly as a party piece. On the other hand it's not something I'd be advising people to do.

 

[myquest]

30mA will kill you hence the requirements for a 30mA rcd on sockets in the UK now. Could what you are getting be static? You have lots of rotating bits and very dry weather.

I'm suprised that the learned folk who set the regulations would make the tripping current the same as one that would kill you. I would have set it somewhere below but then I' m not all that learned!

 

[lpdsn]

When I use my petrol strimmer if my elbow touches the motor I get electric shocks down my arm, just an irritation but is exposure to these dangerous to old folk?

When I was a sixth former I did a few tests on my classmates. They all survived, but...

Being a bit more serious ... there was a huge variation in the resistance of the subjects. A factor of 12 between highest and lowest across a relatively small sample. So some people are very much more vulnerable to electric shocks than others. I did find that those of us who messed around with electrics and electronics had a far higher resistance than the others, but that could've been just a coincidence (just pre-empting JD questioning the statistical significance of my measurements )

 

[lpdsn]

Though I did prefer to work with both hands in my pockets.

That would've got you a job with the local council.

 

[William_H]

I'm suprised that the learned folk who set the regulations would make the tripping current the same as one that would kill you. I would have set it somewhere below but then I' m not all that learned!

There are many variations to the dangers of electrocution. AC 50 hz is most dangerous because the alternating voltage tends to make muscles of the hand or arm clench so you can not let go the source. DC or a single pulse as in ignition is not so dangerous because it generally makes you jerk away from contact. This jerk as in motor cycle riding or being on a ladder can in itself be dangerous. Any electric current through the heart can either stop it or change the rhythm. The 30 ma response with RCD may be a more practical limit to what can be achieved by RCDs and high enough to avert nuisance activation as compared to most human tolerance to that current and common current through the body. Which of course depends on skin moisture and contact area.
The voltage spike of the ignition of the strimmer is most likely generated by an electronic inductive discharge type of magneto and voltage is likely to be similar to that of a car. The plug gap and cylinder pressure being similar.
It is possible that the shock is coming from a lower voltage part of the ignition system which comes out as a wire which is grounded to stop the motor. As said the shocks though mild could lead to a accident of some sort but not in themselves dangerous. olewill