Safety 101: A word on mains and safety. P1

Posted by on December 4, 2011

It is said that you can disrupt the normal heart rhythm by passing no more than 10mA across the heart, this should be enough to cause fibrillation in most cases. What this means is that eventually you’ll die of cardiac arrest if you don’t get defibrilated in time (assuming of course you are in a shockable rhythm or can be brought to one to begin with). Heart failure is just one of the many risks involved.

Because of this you’d want to take precautions when working with mains at home, whether it’s 110VAC or 220VAC it doesn’t matter; both can be lethal if the right (or wrong) conditions are met.

A big part of safety comes from your behavior. As a general rule of thumb never grab things with both hands, specially if they have a metallic chasis and they happen to be energized — This is why most people will tell you to place your left hand behind your back or in your pocket, the reason for this is just so you don’t create that return path through your ticker with your hand by touching something that happens to be on the neutral side of the circuit while on the other hand you may be mistakenly touching the live side and vice versa.

Now, given the right conditions you could be grounded and thus your feet, or legs (point of contact) would become the return path, if you are touching live with your left hand chances are you may not make it.

So you can’t assume any safety measures are in place or functional, for instance the earth / ground wire or an RCD may be damaged or non existent. Even if they are tested and functional you still have to conduct proper behavior to avoid accidents.

Remember: Behavior. Don’t assume, don’t fool around — Be smart or be with Darwin.

We’ll discuss how to safely work on mains related projects at home on the next entry.