Wiki first safety page - SECOND DRAFT for comment

[JohnW2]

Well, yes, 0.5mA is usually taken to be the 'threshold of perception'

No, that's something different. The threshold of reaction is the current that causes a muscular reaction, i.e. a movement that might result in falling off a ladder..

In that case, you're saying that the thershold of perception and threshold of reaction are the same - since, as I said, the threshold of perception is also generally taken as being about 0.5mA. As I said, that current will usually be far too low to produced any directly-physiological 'generalised' muscle reaction, although it would probably produce some local muscle contraction close to the point of contact, which might be enough to cause an incident. However, as a said, anything perceived (as in thunder) has the capacity to produce a widespread 'response', which could result in falling off a ladder etc.

Whatever, as I said, I've given in!

I'll be post a 'third (hopefully near-final) draft' for consideration fairly soon - and that will incorporate your wording as regards this matter! - so, if you were considering commenting more widely on the draft, I suggest that you await the new one!

Kind Regards, John

 

[JohnW2]

A THIRD draft has now been posted in a new thread ( ( here ) . I would be grateful if any further comments could be posted in that new thread. Thanks.

Kind Regards, John

 

[JohnW2]

Well, yes, 0.5mA is usually taken to be the 'threshold of perception'

No, that's something different. The threshold of reaction is the current that causes a muscular reaction, i.e. a movement that might result in falling off a ladder..

Just to be doubly sure (even though I already was 'sure'), I've just done the experiment. At 0.5mA (about 10V and wet fingers), I feel absolutely nothing, let alone get any 'muscular reaction'. The same with 1mA (about 12V and even wetter fingers). I have no immediate plans to extend the experiment to determine what current I can feel and/or which produces a 'muscular reaction'

Kind Regards, John

 

[securespark]

I have no immediate plans to extend the experiment to determine what current I can feel and/or which produces a 'muscular reaction'

Now I'm disappointed.

Meanie.

 

[stillp]

Don't bother with the test, just buy a copy of "DD IEC/TS 60479-1:2005
Effects of current on human beings and livestock. General aspects". It's only £196!

The thresholds are different for DC and AC.

 

[JohnW2]

Don't bother with the test, just buy a copy of "DD IEC/TS 60479-1:2005 Effects of current on human beings and livestock. General aspects". It's only £196! The thresholds are different for DC and AC.

My tests were with AC.

Kind Regards, John

 

[JohnW2]

I have no immediate plans to extend the experiment to determine what current I can feel and/or which produces a 'muscular reaction'

Now I'm disappointed. Meanie.

OK. OK. The lowest (AC) current I can feel (as a minor 'tingle') is about 1.2 mA, certainly with no 'muscular reaction'. At 1.6 - 1.7 mA, it starts getting fairly unpleasant, with the temptation to pull one's hand away (consciously), but still no unconscious 'muscle reaction'.

If you want to know the lowest current which does cause an unconscious 'muscle reaction' I leave it to you to do the experiment

Kind Regards, John