ECN Forum Forums General Topics of the Trade General Discussion Area Splicing a new light fixture while circuit is energized

I stand corrected.

Sparksalot, my sources tell me that 2 to 10 mA is enough to cause muscular contraction, and 5 to 25 mA causes a painful shock and inability to let go. Obviously, it all depends on skin resistance. If you are sweating you will get nailed worse. Gfci's were set up to trip around 5mA because any more than that could cause someone to get killed. Sure, ventricular fibrillation occurs around 50mA, but prople can get killed at lower currents because of the muscular contractions and the "lock on" effect, and falls or cuts resulting from such effects can cause someone to be killed.

hi,
i have only one thing to say here......

"electricity has no respect for ingonrance"..

nothing personal...just good advice...no circuit is so important that a person should ever work on it hot...i know some testing must be done hot but if you are going to extend circuits or add additional devices or make changes to an exisiting system...you wouldnt want to make yourself a link between the circuit and the power company now would you? more commonly referred to as a "human fuse"

SHUT IT DOWN..LOCK IT OUT AND TAG IT..PERIOD

i always lift the wire off the breaker if possible just to go one step further
..be safe..whatever your doing isnt worth anything if your dead
-regards

frodo


[This message has been edited by frodo (edited 01-21-2002).]

Elzappr
OK, you got me to look it up. I once worked for a very large oil company. They were very big on safety and the numbers they gave were about 150ma. I checked numerous sources online and the numbers ran as low as 70ma and up to 300ma. These were sources such as doctors and worker safety organizations so I think we need to figure the lethal level to be somewhere in that range. Also, as to different effects depending on sweating or being grounded, remember, current is current. If X amount of current is flowing though a person being sweaty or well grounded or whatever will not affect the effect. In other words, if a person were hooked up to a limited current source of say 5ma, no matter how well grounded or sweaty or good the contact they would not feel more that minor pain. Another interesting thing I found, according to at least two sources women actually have slightly less tolerance for electrical shock than men. But then, since they tend to be less macho than men they probably are more careful too.
Don

One of my manywonderful mentors, now retired, used his fingers as a tester.
He smoked those filterless camels, many times down until his fingers burnt, which he no longer felt towards the end of his carear.

I have a Bio-Medical Electrical Engineering professor who deals with electrical stimulus and monitoring of body functions. He has always felt that 1mA is enough to stop a heart or create a condition that can interrupt the hearts natural rhythm.

I don't even like working on a live panel let alone changing/wiring devices on a live circuit. I hate the mentality of any company/person that can't be bothered to lose a few minutes of light or productivity in the name of safety. Seriously, what have we come to that a person's life is less important than the bottom line or even operations of a company? It annoys the crap out of me.

Colorado, you sure dug up a dated thread ... more power to you! If nothing else, we got to hear some comments from folks who REALLY don't like engineers

There is some basis to those bitter feelings. I've been in too many offices where everything was controlled off one switch, or there was a shared neutral between all the lights, with the result that you had to either work hot, or in the dark. Pick your risk multiplier!

That situation, thankfully, has become lees a problem as the result of 'energy codes.' The "experts" have suddenly discovered that light use less energy when they're turned off.

It was just a situation ... opening a shared neutral (something had been tied in that I didn't know about) that led to my buying the $600 fried guts of a change machine. Oops.

So ... here's my solution ... especially for lights: use the "Wago" or "In-Sure" type connectors, taking care that there is at least one extra opening, for adding future wires. These connectors make "adding hot" as safe and simple as it's ever likely to be.

Someone put the light in originally, and there were no lights on before they put some in.

This is when a flashlight comes in handy

The voltage is less of a factor than the current capacity. A 12V automotive battery for instance... has a current capacity of maybe several hundred to over a thousand amps and could easily kill someone shorted.

Also the path through the body is a factor. Since we're full of water it comes down mostly to luck, but it doesn't take much current at all to disrupt the nerves controlling your heart and lungs. That's what'll usually kill.

So... just be careful everybody.