Voltage/Amp related question

[TC10284]

This may be a totally n00b question but this one has been bugging me for a few days. I know that amperage and not voltage is what kills/injures most people when they get shocked. However, I've been wondering, if the max output on 12v, 5v, and 3.3v power supplies such as in a computer that has let's say, 20A on the 3.3v line, 30A on the 5v line, and 10A on the 12v line. Would that not be dangerous? I've heard that just amperage in the 0.x range can be dangerous to humans.
Are those figures just the maximum amperage output?

Thanks for answering my n00b question =)

 

[Guest]

It is all still based on ohms law...V=IR. In this case your body = the R in the formula.

There are two ways to die from electrocution that I am aware of: 1. the most common way ~20mA through your heart. Interupts heart rythym and boom your dead. 2. large enough amounts of current through some other part of the body such that the tissue damage kills you, ie you hear about body parts exploding off during lightning hits, taken to an extreme this is bad.

The heart one is easy to do since we use our hands to grab things. Grab a plus lead with one hand and it's minus lead with the other and guess which organ falls right in the current path? Yes your heart. Depending on your bodies conductivity and the voltage applied you can die from doing this. Thus the old electricians rule for survival...Only work on live low voltage lines with one hand and you will only get a nasty shock but live through it.

Lightning and other high voltage sources just need to be stayed away from. Lightning for example has already ionized a path from the ground to a cloud so imagine how little impedance you must represent. The idea of a human filament comes to mind.

 

[Fastboatslowcomp]

Check this out if knewton's explanation didn't satiate your curiosity.

http://www.dansdata.com/gz013.htm

It's important to remember that your body will be a better conductor of electricity under different conditions. A given voltage/amperage can be harmless uner one condition and deadly under another.

Ever heard of someone dying while climbing an electrical tower? High tension wires carry enough voltage/amperage to kill you from several feet away if you are grounded (touching the tower grounds you). But a bird can land on the wire and not be killed because it is not grounded.