Let’s Review Basic Electrical Theory
Depending on their level of expertise and licensing, pool service technicians are expected to make basic electrical connections, troubleshoot underwater lights, and service other electrical equipment. To work with electricity safely and profitably, it is necessary to have a basic understanding of how electricity works, is controlled, and conducted.
To understand electricity, many people find it useful to use the analogy of water flowing through a pipe.
For electricity to flow, there must be some sort of difference in pressure, called potential, or voltage. A wire with no potential has no current flowing through it. But when it comes into contact with something that has electrical potential, it will accept current until the potentials are equal in both places.
This potential can be pictured as similar to two tanks of water separated by a valve. Tank A is full, and causes pressure at the valve. Tank B is empty until the valve is opened, at which point the water flows until both tanks contain the same amount of water, equalizing the pressure in each.
Electricity works in a similar way, flowing from a place of greater electrical potential to a place of lesser potential.
The earth is considered electrically neutral. This is why we ground electrical panels and devices. That way, if the current takes an unexpected path, it will be attracted to the earth.
In a home, for example, electrical service includes an electrical panel connected to a copper stake driven into the soil. An appliance that is “grounded” has a wire that is connected to the electrical panel, which is attached to this grounding bar. That way, if a wire within the motor of the appliance were to accidentally touch the metal case of the motor, the current would be grounded harmlessly through the ground wire into the earth. Appliances are grounded to prevent a person from becoming the path through which electricity flows to the earth.
At swimming pools, appliances and metal objects are also bonded. That means that the appliances and metal objects are all physically connected to one another with a heavy gauge wire so that all exist at the same potential. This way, if a person touches two conductors, because they are at the same potential, no electricity will flow though the person.
The human body operates with electricity – small electrical impulses that stimulate muscles or transmit energy in the brain. That means that the body is an excellent conductor of electricity.
But like any appliance, too much electric current delivered to it can destroy it.
An electric current of about 30 milliamps or greater will cause muscles to contract uncontrollably, meaning that if you grab a hot wire of that or greater current, you probably won’t be able to let go. Within a short period of time, that current will disrupt the normal heartbeat, causing death.
Every conductor offers some resistance to the flow of electricity, similar to friction in a water pipe. Some conductors allow current to flow better than others because they offer less resistance. This resistance is measured in ohms. The better the conductor, the lower the ohms measured. Also, the shorter the length of the conductor, the lower the ohms. Two types of current are used. There is direct current, such as that provided from a battery, which is designed to provide a certain amount of voltage until it is exhausted. For example, a 9-volt radio battery will always deliver 9 volts. But appliances use power at different rates. If an appliance uses little power, it may draw on the energy slowly, at say one amp per hour. A different appliance may draw on the energy more quickly, at two amps per hour, meaning that the battery will be consumed twice as fast.
In these dc battery circuits, current flows in one direction, which we define as the negative side of the battery to the positive. Then there is alternating current, which travels in one direction and then reverses.
Alternating current can be stepped up, or stepped down with a transformer, which permits the transmission of high voltage along municipal power lines that is transformed to lower voltages at homes and businesses.
Alternating current is delivered to homes and businesses for appliances that are designed to accept it at either 110 volts or 220 volts. Both of these designations are averages, because most appliances use a range of 108 to 127 volts, and 215 to 250 volts. That’s why it’s common to see voltages for appliances expressed as 110, 115, 120, or 220, 230, 240.
Alternating current is also delivered at a certain rate. In the U.S., power is delivered at 60 cycles per second (60 hertz) whereas in Europe and other places in the world it is delivered at 50 hertz.