Service entrance electrical house wiring continued

The service entrance for electrical house wiring 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. Breaker box grounding is important in case of overload, the electrical current will be directed into the ground.


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 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.

house wiring diagram

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.

residential wiring

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 a 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.

electric symbols



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.

home wiring



It helps to make a top view of the home 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.

wiring diagrams



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 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.

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