Monday, January 21, 2008

Fundamental Electricity

Many people attempt simple home electric repairs every year and end up injured, killed, or causing an unsafe situation. I think that much of that could be avoided if they possessed a fundamental knowledge of electricity.

Of course, just about all of that would be avoided if people hired a professional. But not everyone is going to do that for various reasons.

The best place to get basic electrical knowledge is to take a course at your local community college. And there are many good books on the subject.

The purpose of this series is to help those (that wish to do simple home electric repairs) understand the basic principles. I am not a master electrician but I have training in basic electricity, electric motor control and in the National Electrical Code. And I feel qualified to write on simple electric matters.

This is not designed to be a course nor should it be considered expert advice. This is only an aid that should be used in conjunction with other things, like books or courses.

I have not gone into any formulas or quantum physics in this work. I have tried to keep it as simple and easy to understand as possible and yet convey the principles to you.

However, this work comes with a warning label that you should read first:

Electricity can be very dangerous. It is nothing to take lightly. If you remove a switch or outlet cover and are not completely familiar with what you see, do not attempt to fix it.

And under no circumstances should any electrical job be done with power going to the work. All wires should be dead and double checked beforehand.

Never guess. Always be sure or do not proceed. Get expert advice or hire a professional rather than do anything that you are not familiar with.

Anytime you finish an electrical project, check, double check and triple check, your work, before restoring power. Mistakes can cause serious repercussions.

If you do not live alone, tape a note to the breaker box, telling everyone that you are working on the electricity and not to touch anything. You don’t want someone coming behind you and flipping on a breaker while you have bare wires in your hand.

If you are working on a light or ceiling fan, don’t just turn off the switch. Kill the power from the breaker to be safe.

Thank you for reading the warning label. Now let’s proceed:
Here are a few projects that can be done by homeowners, with a basic knowledge of electricity.

1. replace a light switch
2. replace an electric outlet.
3. install a ceiling fan
4. replace a ceiling light
5. fix an electric plug
6. fix a lamp

But it is important to have a fundamental understanding of electricity. So let’s get started.

Fundamental Electricity

At your local power plant there are many big generators. They spin and churn out electric current through the principle of magnetism. Here is how it works:

You probably already know that if you attach a coil of wire to each end of a battery, it will make an electro-magnet. Did you know that it works in reverse also? If you spin magnets over coils, it will produce electricity.

Electricity refers to an electron in each atom jumping from one atom to another. This is a chain reaction and the electrons keep jumping until they reach the ground. The ground rebalances them.

When you rub your feet on a rug, you are unbalancing the electrons and when you touch something that is in contact with the ground, there is a zap as the electrons are rebalanced or neutralized.

Let’s think of electricity as water, and the wires as a garden hose. Water flows through a hose at a certain rate. This rate is called the current.

Electric current is the amount of electricity that is flowing through the wires at a given time. The current is measured in amps.

The water in a hose is at a certain pressure (psi). The pressure that electric current flows is called voltage.

The size of the hose offers resistance to water flow. The smaller the hose, the harder it will flow. The smaller the wire, (conductor) the greater the flow of electricity, due to resistance. Electric resistance is measured in ohms.

Let’s use the garden hose again. If you have water flowing through a 1 inch diameter hose and hook in to a ½ inch hose what will happen? The water flow will double. This happens because the ½ inch hose has twice the resistance to the water, forcing the water to flow faster.

Now let’s take that to electricity. You have 120 volts of electricity flowing through a wire that is rated at .25 ohms. And you splice it to a smaller wire that is rated at .50 ohms. What is going to happen and why? Just like the water, the current will double from 30 amps to 60 amps.

The excess resistance and increased flow will cause a great deal of friction, which will generate a lot of heat and possibly burn up the wire and perhaps cause a fire. So it is very important to use wires that are big enough for the job. And this applies to extension chords too.

Wires are sized by gauge...the smaller the gauge, the larger the wire. For 15 amp circuits you can use number 14 wire or bigger. If you are not sure what a circuit is, we’ll cover it in a later part.

For 20 amp circuits, use number 12 wire or bigger. For 30 amp circuits, use number 10 wire or bigger.

Let’s review. Electricity is caused by a chain reaction of imbalanced electrons. The flow of electricity can be compared to water. If you use a smaller hose (wire), the flow(amps) will increase due to increased resistance.

A wire that is too small for your use will get hot due to friction from greater resistance. This may cause a fire. It is imperative to use wires that are big enough for the job.

Next, we will talk about electricity as it leaves the power plant and gets to your house.

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