The residential electrical service is probably the most basic of all electrical services between commercial and industrial.
Your homes electrical service is measured in amperage and voltage and is determined by several factors. Such as outside square footage of the building, number of floors, basement and attic usage, kitchen needs, air conditioning, heating, and other types of equipment. These fundamentals are established by the National Electrical Code NEC and local amendments.
There are eight parts to your electrical service.
The utility company conductors (overhead or underground)
Your conductors (in pipe or cable)
Pipe or Cable
Meter and socket
Main water pipe or ground rod
Disconnecting switch or circuit breaker
Electrical service panel (main panel)
Circuit breakers or fuses
The utility company determines the size of the conductors brought to your home also whether the service will be overhead or underground.
The size of your conductors or cable is determined by the amperage of your service 60Amps, 100Amps, and 200Amps (I will spare you the details of this relationship). Cost is a determining factor of whether individual conductors or cable is used and can determine if copper or aluminum is used.
Whether pipe or cable is used can and may be determined by owner’s preference, cost, location, national and or local laws.
Electrical meters are connected to the electrical system by the meter pan socket (enclosure). The meter can be located inside or outside (outside is the best so you do not have to be around when the meter reader comes). Permission must be given by the utility company in order to install the meter outside, along with the proper spacing around the meter.
The water main (street side of water meter) is used to ground (keep at zero potential) the electrical service. If the water main is used to ground a new system a ground rod (eight to ten feet long) must be driven into the ground as a supplement, two rods is the standard practice.
The disconnecting means is used to shut off all power to the house in case of emergency or as needed and is always placed after the electrical meter. Disconnects can be part of the electrical meter pan socket, inside of the service panel or in its own enclosure somewhere between the meter and service panel. Some services have no disconnect anywhere, which means the service is old, but if it is a new service, it is in violation of national and local rules, but is not entirely dangerous, because power can be shut off my turning each circuit breaker off.
Electrical panels used in residential installations are normally called load centers and are available in many sizes but only one color gray.
Circuit breakers and fuses are known as over current protection devices OCPD. They come in many types, shapes, amperages, voltages and brands. Their primary function is to protect equipment and property, NOT PERSONS.
They will protect a circuit from an overload (to much current drawn) a short circuit (the black, red or blue and white wire comes directly in contact). They will not effectively protect you from a ground fault (the black, red, or blue wire contacts metal) unless enough current is drawn to trip the circuit breaker.
There are many different types of circuit breakers, but the ones you will find in a residential electrical panel can be any combination of
This type trips based on the size of the magnetic field created by the current
A bi-metallic strip made of two dissimilar metals that heat up and separate when to much current is drawn, causes this breaker to trip
A combination of the two for sensitive electronics
Ground Fault Circuit Interrupter GFCI
This type uses a complex internal circuit that can sense any change between the black and white wires (as low as two milliamps); this type will protect PERSONS from a ground fault
Arch Fault Circuit Interrupter AFCI
This device is designed to protect equipment and property, from arc’s (flashes when you insert or remove a plug from a receptacle)
The shape of the circuit breaker is determined based on the amperage, voltage, and number of poles needed (single pole, or double pole). Some GFCI and AFCI circuit breakers can take up to two spaces in an electrical panel so planning must be used.
The number you see on or near the handle is the over current rating (15, 20, and 30) this rating (in AMPS) determines how much of a load can be placed on the circuit regardless of the size of the conductors. In order to protect the circuit breaker from wearing out quickly you can only use 80% of its rating.
If you examine the circuit breaker even closer you will notice, another number stamped onto the side of the breaker (5,000 or 10,000 amps). This number represents the amount of current that the breaker can hold back during a short circuit, if this amperage is exceeded the breaker will possibly melt or explode.
In a residential setting there are two voltages used 110/120 volts and 220/240 volts
When it comes to brands there are many to choose from, (I will not list them). Most manufactures not only make circuit breakers but the load center also. Some manufactures circuit breakers can be used in other brand load centers. You may have discovered this on your own, but for the most part this should be left to your favorite electrical contractor.
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