Service entrance electrical wiring for home construction

Service entrance basic electrical wiring in home construction

This is the service entrance part to basic electrical wiring for 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 an electrical wiring
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 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”.
breaker box

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 eletrical 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.

service entrance wiring

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.

Service entrance wiring continued

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