Hey guys had a few people have had a few issues of late and i hope this post will help prevent some of the mistakes made by others (Myself included)
The First thing you must know is the most basic thing.
Electricity is Dangerous and its is important to be carefull with it no matter the voltage or current.
Even low Voltage and Current can cause Serious injuries as low as 2 Volts can cause serious burns and muscle, Nerve and Cardiac damage.
ITS NOT VOLTAGE THAT KILLS ITS CURRENT:
Current is measured in Amperes.
0.0001A (1 Milliamp)
0.001A (10 Milliamp)
Will Produce a small tingle Sensation to a painful shock and possibly Minor Burns.
0.002A (20 Milliamp)
0.007A (70 Milliamp)
Will Produce a Serious Painful Shock with varying degrees of burns muscle Tissue and Nerve Damage and Respitory Problems at the upper End.
0.008A (80 Milliamp)
0.01A (100 Milliamp)
Is getting into the lethal Range with severe Respiratory and Cardiac Damage
0.01A (100 Milliamp)
0.02A (200 Milliamp)
Lethal, Severe irreparable Damage to Nervous system Cardiac Muscle and respiratory System.
So nothing on the Output side of a Computers Power Supply Provides 100 Milliamps
This Statement is inaccurate PSU's can supply 5-20A on the output (that figure maybe inaccurate for some PSU's) though it is unlikely you would receive a shock that large it is imperative to protect yourself because there is always the chance.
We still need to protect our selves and the Sensitive Hardware inside.
A computers PSU Definatly has the Ability on the output side to cause Severe Burns respiritory problems and nerve damage and needless to say the input side is very capable of being lethal.
So here are some tips to keep youself and your hardware safe
1. Take any rings or watches off your hands and wrists when working on your computers.
2. Low hanging Jewellery like necklaces and some earrings should be taken off (I don't recommend tucking them in because the have to opportunity to untuck them selves and i don't like to give them the opportunity)
3. Rubber Soled shoes, Rubber Does Not conduct electricity and effectively makes your bodys resistance to current to infinity. the disadvantage is it increases your ability to damage equipment with electro static shock because it will not dissipate through your feet into ground.
4. Creating a Controlled Short circuit, This Method is not ideal but will save your life the idea is to create a path through your body with less resistance to current then your chest the most common route for electricity is in through one arm and out through the other across the chest causing more damage.
You can use an antistatic strap on both your wrists this way if you do touch a live circuit and receive a shock if done correctly it should not propagate further then your wrists though you will still receive burns and damage to your hands an wrists.
5. My Favorite and the safest way to protect yourself from shocks is to simply turn off the power you should not unplug the machine from the wall this does two things.
A. Keeps ground connected to the machine so that you can ground yourself on the machines case to prevent electro static damage to components.
B. Allows the High voltage capacitors in the PSU to dissipate there stored charge quickly and safely.
Now if you are to work on a Power supply one more safety recommendation would be to leave it plugged in WITH THE WALL SOCKET OFF for 24 hours to allow it to discharge safely.
Regardless of your protection method you should always protect yourself by not creating short circuit or allowing two wire to touch or anything like that even if the power is off gives you a good work ethic and could possible save you from an accident.
The most common symptom there is something wrong with your circuit is Smell and it is your most valuable sense when working on electronics because overheating and short circuits will produce a sulphur electric smell even before you see smoke and sparks if you smell this smell immediately unplug the circuit causing it before it causes severe damage to you or sensitive components. Obviously Smoke and Sparks or even fire are sure signs there is something wrong and should have the power removed from it immediately.
Also two other Points i forgot to mention that are Important.
Having a Circuit Plugged in with the outlet off is safe, Capacitors store charges but having ground connected allows them to discharge more quickly and safely then not having a ground source.
This is probably the most important piece of advice i can give you and EVERYBODY SHOULD KNOW THIS your family and friends included because this is a very common mistake and it happens allot even to people who donot know about electronics or circuitry.
If you see some one being electrocuted DO NOT UNDER ANY CIRCUMSTANCE touch them because electrocution to put it simply is contagious meaning it can travel through that persons body into yours and be just as lethal the appropriate action to take in these situations is to immediately cut the power source if it is safe to do so.
I may have got the Amp values wrong but the Milliamp Measurements and statements are accurate i apologise if i did (sorry im writing this all down from memory)
I Hope this helps people and as always if you have any questions post em up and i will try to answer them ASAP.