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Seriously, don’t try to wire your home if you don’t know how — even if it will save you tons of money

If you're going to attempt DIY electric wiring, you should be prepared to understand how to connect all these wires correctly. It's not for the faint of heart. (Tim Carter)

Q: Tim, it’s a very long story, and don’t think I’m crazy. I’m building a new home and wondering if I can install all the electrical wiring myself. It’s not a big home, but it’s got all the things going on you’d normally have in a home, including quite a few three- and four-way switches. I’ve watched a bunch of online videos, I’ve read a few authoritative books and I’m feeling pretty confident. What am I missing? What would you do if you were me? — Margo F., Albany, Ga.

A: Margo’s in an interesting predicament. My guess is this is a financial issue where she’s trying to trim her overall budget. I can understand that. I can also understand developing a sense of bravado after watching online videos that most likely only tell you part of the story.

I’ve wired lots of homes, including my daughter’s new home in Maine just in the past few months. It’s important to realize that the actual aspect of nailing up boxes and installing the cables is not overly physically taxing. The challenge is to do the work so it meets or exceeds the complex National Electrical Code (NEC) by the National Fire Protection Association. This book is a collection of hard-earned safety standards that many have dedicated their lives to so that you and I can reap the benefits of electric power.

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I don’t know that I’ve ever seen a news story where a person has drowned in their home because of a pipe leak, but dig deep into the national news each week and you’ll find stories of people and pets dying from fires traced to electrical issues. You need to understand that if you decide to install electrical wire, you’re indeed playing with fire.

That said, I don’t want to dissuade you from trying. Another key point is that each master electrician out there started day one on the job not knowing which colored wire nut to use when. A homeowner can successfully and safely install electric wiring in a residential project with some sound advice, an assist from an electrician and a heavy dose of common sense.

I could write for hours and hours about the small nuances involved with residential wiring. First and foremost, let’s talk about the size of the conductors, or wires, in the cables. A spool of cable is what you see at the home center, and here in the United States it normally will contain two insulated wires and an uninsulated bare copper ground wire.

The NEC requires certain circuits in the house be fed with wires that can handle a maximum amperage. For example, kitchen countertop circuits need to handle 20 amps. An electric clothes dryer almost always calls for a cable that can handle 30 amps. Your electric stove/oven may need 40 or 50 amps. The NEC allows many normal outlet circuits in a house to be 15 amps.

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You can’t mix and match wire sizes on circuits. All the wires/cables on a specific circuit protected by a circuit breaker must match the rating of the breaker. Are you confused yet? I think you can see where this is going.

Things you might not even consider come into play. The location of the drilled holes in wall studs and floor joists is critical. The NEC discusses this, and you don’t want drywall screws or finish trim nails puncturing your cables. The number of cables that can be stacked on top of one another when nailed to a wood stud is important, too.

You need to understand how many conductors, or individual wires, are allowed inside certain boxes. The NEC discusses the cubic-inch volume of boxes and relates it to the number and size of the conductors. Some modern boxes have the maximum count printed on them. Is your head spinning yet? We've still got so much more to discuss!

Wiring for three-way and four-way switches is not hard, but you need to understand how it all works. A few years ago, I recorded two separate videos showing how to wire up each switch, and these are on I prefer using a special cable, called a 3 wire, between these switches. This cable contains an extra wire in it that normally has red insulation on it. After watching my videos, you'll understand why this special cable with the extra conductor is so helpful.

You’ll need to fully understand the different circuit breakers that are now required by the NEC. I clearly remember years ago when the ground-fault circuit interrupter (GFCI) breaker was introduced into the code. Not only are you required to use those in certain wet locations, but the NEC also now requires an additional arc-fault circuit interrupter (AFCI) breaker on many other circuits.

Here's my advice. Seriously consider hiring an electrician who will allow you to do lots of the mundane work such as nailing up the boxes, running the cables between them, and even allowing you to connect up many of the switches and outlets after the drywall is up. But allow the electrician to do all the truly complex aspects that only come with years of experience.

Don’t forget, there’s a very special way that the wires are stripped and looped onto the screws on outlets and switches. Mess this up and you probably will become a grim statistic.

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