This is the service entrance part to basic-electrical-wiring for electricity of residential dwellings. Now this is where the fun really begins, but this is also where a lot of first time builders start to doubt themselves. I am going to start with the basics and move through the entire process, but I’ll keep it very understandable at the same time.Now, it’s not my intention to discourage or frighten anyone from doing their own electrical work, but respect for Electricity needs to be observed and never put aside.If you lose your respect for these lines at any time, you stand a good chance of finalizing your life insurance policy. There is no reason at any time to be working on a live circuit, especially a 240-volt line.
There are detailed instructions available from the NEC (National Electrical Code) that can be used as a basic guideline for all basic-electrical-wiring, but local codes from the Building inspectors and Electrical Inspectors always take priority over national codes.
Local Electrical Inspectors are a very good source of information because they are the ones holding up the hoops we all have to jump through. In all honesty, I am very glad I was forced to jump through a lot of hoops from my inspectors, although at the time I was really bent.
When I sleep at night, I know the fuses and circuits and wires aren’t overloaded because that inspector made me tear them out and redo them, -----twice.Let’s get started from the beginning assuming that you are still using the temporary power hook up the utility company rigged up for you. It’s been a struggle with only a few outlets.Now it’s time for some real power! The utility company providing to the electric supply will put up the meter and base. Everything after that or rather, the lines going to the service panel and all the circuitry and fuses are the homeowners’ responsibility.Let’s start out by first making a basic-electrical-wiring plan for where we want everything to be located. It is a good idea to decide where to put the service panel. The Electrical Inspector will have some advice on this matter. There are specific requirements that can’t be compromised.The service panel will be on the inside of the house and will hold all the fuses. All the circuit wires will be connected to it. The service panel needs to be close (usually within a few feet) to the service entrance or meter on the outside wall of the house. A smart electrical contractor will put the service panel in a convenient location.
The service panel will have to be a specific height and distance from the floor. Also, the meter will need to be accessible for the power company. This means that wherever the service entrance is on the outside of the house, the service panel on the inside of the house will have to be just about on the other side of the wall.
So don’t put a living room there on that side of the house because a breaker box makes for a poor conversation piece while entertaining guests. A garage or utility room would be a better option to house the service panel box. The Electrical Inspector will help you with the details of any basic-electrical-wiring for the service panel placement.The illustration below shows a service entrance and meter with an overhead supply. This helps show the proximity between the service entrance outside and the service panel inside.
The utility company will wire the service usually to the meter, then from the meter, you run heavy gauge cables through the wall into the service panel box and connect them to the hot terminal bus. The type of cable used from the meter to the service panel is something like #000 Aluminum rated at about 200 amps, and there are usually 3 of them providing enough current for a 200-amp service.
The illustration shows a typical type of a basic-electrical-wiring service cable used in residential dwellings. This will usually have a black covering. This is a service panel that is commonly used. It is also known as a “breaker box”, or a “load center”.
When considering a service panel, the minimum requirement that I would recommend would be a 200-amp, 40-slot load center. The higher amperage rating is a code requirement in most parts, but the slots for breakers is often left up to the electrician. An owner/builder might be tempted to opt for a smaller and cheaper service panel with fewer slots, but inspectors are becoming real sticklers on dedicated electrical circuits.
There are many new code regulations that didn’t used to exist so one needs to plan for the future.So now that we know what the basic-electrical-wiring service entrance, the meter, and the service panel are, let’s get them all wired together. You can get the wire at an electric supply store. You will connect all the wiring and have to pass your first inspection before the Electrical Inspector will give the utility company permission to connect the power.That’s a good thing anyway, because you will be working with two 120-volt cables and a neutral cable, three wires in all. They won’t be energized until everything is sealed up and secured.The picture below illustrates how the 3-wire service leaves the meter and ends up inside the service panel box. The 2 black wires are then connected to the hot bus, and the white or neutral is connected to the neutral bus.
There are special conduit fittings available at most electric supply stores that make the job look more professional and also help keep moisture out.
You can use either a hole saw or a large spade bit to make the hole in the wall for the power cables. Once the power service from the meter and the service panel box are connected, then you will need to run a system ground wire to a grounding rod.
The grounding wire is just a copper wire made for that purpose. It attaches to a grounding screw usually at the bottom of the neutral bus.
The copper line typically exits through the side of the house toward the bottom and attaches to the grounding rod or the plumbing if metal pipes are used.
Grounding rods are about 4 feet long and made of copper. They can be hammered in close to the foundation.
Your service panel box or breaker box will hold all the breakers or fuses and every circuit run in the house will begin at the breaker. The hot lines are either black or red wires.
Each electrical-house-wiring circuit run begins with a hot line (black or red) connected to the breaker, a neutral line (usually white) connected to the neutral bus bar, and a ground wire (bare copper) also attached to the neutral bus bar.
From there, it goes out of the breaker box and on to the first outlet, (receptacle) or switch, (lights) or hard-wired appliance (water heater, electric wall heaters and heat pumps).
The breaker box has removable round tabs on all four sides giving access to the wiring. Romex is a common name for cable and one I use frequently. It’s important to note that when a cable enters the service panel, the hole needs to have a fastener or clamp to prevent the metal box from possibly cutting the wires.
This should give us a good idea how the breaker box is put together. From this point, it’s a matter of laying out the many circuits and mapping them throughout the house.The dedicated electrical-house-wiring circuits will be the easiest to map out because the entire circuit goes to just one appliance such as the range, or the water heater, or the clothes dryer to name a few. These are all power hogs and not only do they need their own dedicated circuit, but they also use higher amperage breakers and heavier gauge wiring.
There are two kinds of voltages used in residential dwellings, 120-volt for lights and small appliance outlets, and 240-volt for larger appliances. The breakers determine the difference between the two voltages.
A 120-volt breaker is narrow and only attaches to one hot bus in the service panel. That gives it 120 volts of electricity. The big gnarly 240-volt breakers however, are wide and cover both hot bus bars giving them all the electricity available, which is 240 volts.
Notice the difference in widths between breakers. Also, the larger appliances have varying levels of electrical current needs, so the breakers are also available in different amperage ratings. Let’s make a couple of charts with the symbols and numbers we will need to lay out a good electrical floor plan from this point.These are the symbols used for an electrical-house-wiring floor plan to show the inspector. It also helps to keep things organized on paper. The illustration below shows a useful chart of appliances along with the size of wire, size of breaker, voltage requirements, and the required receptacle.
Almost everything else in the house will use a 120-volt, 20-amp circuit. If you have electric heat, you will need to find out the specifications on voltage and amperage because some heaters use 120 volts and others use 240 volts. Usually the higher voltage heaters run more efficiently.

It helps to make a top view of the electrical-house-wiring floor plan with the different symbols. It may look like a mess at first because there are so many symbols in such a small area to work with on paper, but you’ll get used to seeing and understanding the diagrams and blueprints long before you begin construction on the actual circuitry.The illustration below shows a simple electrical floor plan with outlets, switches, and lights. I found it useful to make several copies of the same floor plan without all the electrical symbols, and then make an overlay diagram of each electrical circuit starting with circuit number “1”.You will need to number your circuit runs at the breaker box anyway, so this is a good time plan it out. On each plan, include only one circuit run even if it is just your water heater or cooking range. Draw the circuitry exactly how it will run through the walls and joists and even include measurements in the plans if you want to.
You might even want to laminate the plans because they will help you years later when you’re trying to remember where you ran those darn wires.

The diagrams can be easy or complex because they aren’t for anyone but you. The idea is to simplify something that is intimidating. That’s the whole idea behind everything I stand for. If something is overwhelming and seemingly impossible to understand, step back a bit, scratch your head a few times, then break it down in your mind to the smallest steps or particles necessary. When you start to understand it at that level, then move on.When planning your electrical-house-wiring circuits, you will want to divide up the circuits with two major points in mind. First, and most important, is that you don’t put too many loads on one line. That makes for hot wires and you’ll wear your carpets out running back and forth resetting breakers.As a rule of thumb, you probably don’t want to put any more than 15 loads on one circuit. A load is an outlet, appliance, or light switch. Both plugs on an outlet or receptacle are one load. This is one of those things that vary greatly from region to region so you’ll need to consult your local codebook.That is one of the reasons you are going to need a large service panel box. Most residential dwellings will use around 30 breaker slots these days.
The second reason to divide up your electrical-house-wiring circuit runs is to avoid total darkness when a breaker trips. Keep that in mind while planning circuit routes. Romex is cheap and it’s easy to run, so try to at least integrate the lighting into several different circuits. In other words, don’t run all your lights on one circuit.