Thread: For the scientifically minded...

Electricity is really very simple.

It works like this:

Originally Posted by thebigspendur

I was just wondering about this as I got a minor electric shock this morning while working on some wiring.

We all know electricity is defined as a flow of electrons. But what does that really mean and what would it take to completely reverse or stop that flow. Also, how would either AC or DC differ in those respects. C'mon I know we have some Physicists here.

The 'flow' of electrons is referred to as the current - like the stream of water falling out of the faucet to the sink. Electricity itself could be described as the water pressure. The potential of having water is there, but not in use until you turn on the faucet - or the light switch.

For our discussion there really is no difference in AC or DC. The electricity itself is exactly the same - as in when the switch is thrown, the electrons flow through the load (the light bulb, the motor, the TV, YOU, ect) it works and we pay the bill. AC is used in most homes around the world because it's easier to transmit over great distances than DC, but the principle is the same.

To stop the flow you open the circuit - with the light switch or the circuit breaker. This removes the electric potential (or the water pressure) from the circuit so you can safetly work on the light fixture or plug (or the faucet) without getting a shock (or getting wet).

As an electrician with 30+ years in the trade I can tell you I get shocked often with 120-277 volts because I know it won't kill me and sometimes I just can't be bothered bathing myself in total darkness in order to do a small repair. It's just as uncomfortable today as it was 30+ years ago and I don't think one ever 'gets used to it'... I do take certain precautions... like keeping my tongue off the hot wire, working with one hand (the one that'll likely get shocked) and not getting knocked off the ladder (which will likely cause much more damage to old bones than the shock would have).

If you're a carpenter you're going to get a splinter, if you're an electrician you're going to get shocked. The trick is to stay away from those splinters that would impale you and not getting a shock when working with more than 277 volts. Line men do NOT get shocked - at least not the ones that are still alive and the dead ones only got shocked once.

The human body is walking balloon filled with saltwater - an excellent conductor of electricity. If you don't want to get a shock it is wise to not become part of the electrical circuit.

I'm going to take it you're not an electrician and I'm going to strongly suggest you turn the power off before working on any more electrical circuits. A voltage tester (a "Tweety") can be picked up at Home Depot or your favorite hardware store for the cost of a non-remarkable razor that needs restoring. Place the device near the wires in question and it will start tweeting. If it's quiet you can hear it when you're standing at the panel and will know when you turn off that circuit.

Note: Lighting circuits are almost never tied in with your plugs, so you may have succeeded in getting the power off to the lights, but the plugs could still take a bite out of you.

Note 2: The box those wires live in is ground. If the hot wires come in contact with that box exsplosive sparks of molten copper and steel along with the sound of arc welding will immediately occur... it's best not to get any of this action into your face.

Have a nice day, Homeowner. Be careful out there...

Electricity is just the most basic interaction that makes everything around us work. It is what makes all the atoms in your body, or your razor stay together, it's what makes them move around. The gravity is different and also works between anything but it's way way weaker than electricity.
What makes you breathe, or think, or eat, or your heart beat is the electric currents in your body. Those are pretty small currents, caused by small charges, that's why you need really big magnets when you image them with MRI.

Now when you have two wires they have plenty of electrons in there that are very easy to move around (in contrast if you had two pieces of wood you have similar number of electrons, but they are very very hard to move.) The only thing that's missing is something to make these electrons move in unison. That's where your power company comes into play - you pay them money, they burn some coal and get that energy that was stored into the coal converted into 'electric field' that can move electric charges between the two wires in your outlet.
Normally they can't jump through the air between the wires (but if it gets very humid they may be able to and you can get sparks from the plasma discharge). If you touch those wires though the electrons that are there under the force that the electric company has provided can just go through your body and that flow is much bigger than the small currents that make your body operate and totally disrupt them.

Sometimes you can recover from this, sometimes you can't. I guess this time around you ended in the first group

The only difference between AC and DC is that in AC the direction of the flow (or the force that causes that flow) flips back and forth 50-60 times each second.

Originally Posted by thebigspendur

I was just wondering about this as I got a minor electric shock this morning while working on some wiring.

We all know electricity is defined as a flow of electrons. But what does that really mean and what would it take to completely reverse or stop that flow. Also, how would either AC or DC differ in those respects. C'mon I know we have some Physicists here.

If you work on electricity be sure to have a tester (meter).
Then learn how to use it.

Old time radio folk used to keep one hand in their back pocket
so they did not turn themselves into part of the circuit.

Years ago I was a union ironworker (structural steel erection) and I was on an aluminum ladder welding. I was soaked, literally, in sweat and even my gloves were wet. The welding lead was hanging on a rung of the ladder by a welding rod bent into a hook and wrapped around the lead. The 'stinger' had the insulator broken off of the top of the handpiece and at some point I dropped it to let it hang from the hook. The uninsulated copper top hit that ladder and gave me a full body shock that darn near knocked me off the ladder. DC current BTW out of one of those big Lincoln gasoline engine welders on wheels.

Just a couple of weeks ago I wired a ceiling fan 'hot' and lived to tell the tale. If you know what you're doing you can chance it. If you don't it is best to turn the power off at the breaker and make sure anyone who might have access to the breaker knows you are working on the switch. An electrical tester and a multi meter are de rigueur for that sort of thing too.

All I know is that as I get older and gravity takes its toll, I am finding it harder and harder to step over electric fences without getting zapped. Electricity does not respect the ravages of gravity. Supportive undergarments, or incredible pelvic floor, are a must when traversing farm land in my neck of the woods.

James.

Christmas tree lights are another one that can give you a real shock if youre not careful! My dad got zapped years back and it literally threw him across the room. Fortunately he was ok, but we all have a very healthy respect for those sparkly little lights now!

What Tonycraigo said. I'm 1000 hrs from taking my electrician's journeyman license exam. Take-home message: body conducts electricity very well, especially the blood vessels and bone marrow. One hand in pocket. Fiberglass ladders only. Turn off power first, and make sure nobody else is going to turn it back on til you're done. Do not try this at home, unless you've read a bunch about it and have somone at home to a) do CPR, and b) call 911 for you.

Originally Posted by northpaw

Electricity is really very simple.

It works like this:

Yeah, that's pretty much how I was taught, too.

Originally Posted by JoeSomebody

Electricity is like running water. You have to have "flow" for it to work. If you stand on something insulated from ground, you will not get shocked because the electricity has no "path" to ground. Hope this makes sense. BTW DO NOT TRY THIS UNLESS YOU HAVE SOME EXPERIENCE. IF YOU DO NOT HAVE THE PROPER INSULATION YOU WILL GET SHOCKED!

Be careful with the insulation from ground. Electricity will jump an air gap depending on moisture in the air, current and distance. I agree with you as far as experience is concerned. Don't be lazy, throw the breaker or main. Takes an extra few minutes. OR....hire a dang professional.

Originally Posted by Birnando

That is basically right.

To put this in easier language:
I can touch the Live and Neutral in a regular outlet. This will hurt, but represents little danger or damage to a healthy person. The reason is that you connect in paralell, and the resistance in your body is really high.
According to Ohm's law, it shows like this:
Voltage/(Apmps*resistance)
This closed circuit has very high resistance and therefore low current.

Now, the real danger is in a regular light switch.
Touching the two wires in one of those, with e.g. a bunch of lightning fixtures attached to it, is a real danger.
That will make a serial connection, and that means that all current in that closed circuit will pass thru you.

Believe you me, you do not wanna try that at home. I've lost 2 colleagues this way, a very nasty way to go...

A current as low as 30mA (that's 0,003A) could be potentially leathal, so beware

I been zapped a few times by a 115V/15amp circuit. No fun! Now I follow the "THROW THE BREAKER" rule. Works every time.