Common Mistakes Made By The DIY Electrician

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There is no place for error in electrical work, just because something works doesn't mean that it was done correctly or that it's safe. Most of the mistakes that DIY electricians make can be easily avoided.

There is nothing more rewarding then to be able to tell others that you did it yourself, knowing that you did it correctly. The problem is that with electrical work, just because something works does not mean that you have done it correctly. Professional electricians serve a rigorous apprenticeship under one or more maser electricians to learn how to do it right. The DIY electrician must learn to do it right by reading books and watching the DIY Network on television. Books are excellent, but there are many things that they do not explain in detail that leads to mistakes. We will look at the eight most common mistakes made by the new DIY electrician in this article.

Mistake Number One: Working Without A Permit

The National Electrical Code (NEC) and the Authority Having Jurisdiction (AHJ) allow the resident homeowner to do almost everything that a licensed professional electrician can do as long as the resident homeowner abides by the same rules. By resident homeowner, we mean that you not only own home but that you are the one residing in it. If you own home but use it as rental property, you cannot legally do any electrical work on the property.

You purchase a wiring permit from the AHJ; your municipal building permits department. At the time, you purchase your wiring permit; you schedule the required inspections to be performed by the AHJ on your work. As a rule, a minimum of two inspections has to be performed, a rough in inspection and a finish inspection. You should not start any wiring project until you have a wiring permit and post it on site as required.

Mistake Number Two: Not Protecting Wiring From Nails And Screws

You can run cables through holes and notches drilled or cut in framing members. You can secure cables to the sides of framing members. You must drill the holes so that the near edges of the holes are a minimum of 1 and ¼ inches back from the nearest edge of the framing member. If a 1 and ¼ inch setback is not possible, the NEC requires the use of steel nailing plates to protect the cables from nail damage. Cover cables laid in notches with 1/16 inch thick, UL Approved, steel nailing plates.

You can run cables along the side of a framing member as long as they are setback at least 1 and ¼ inches from the nearest edge of the framing member. You may need to use 3-M Stackers to satisfy this requirement when running multiple cables. The 3-M Stacker allows you to place the cables on top of one another instead of having to place them side by side.

Mistake Number Three: Do Not Mix Low Voltage Wiring With Line Voltage Wiring.

When roughing in electrical wiring, do not mix line-voltage wiring with low-voltage wiring. You should run them through separate holes drilled at least 6 inches apart. You should not run them into the same device box or junction box unless the box is equipped with a separator designed for that purpose. Mixing line-voltage and low-voltage wiring together is not only a Code violation it can cause other problems. A hum will be induced on telephone and audio-video wiring. Home automation systems can be destroyed if line-voltage wiring comes into electrical contact with line-voltage wiring.

Mistake Number Four: Do Not Pull Too Many Wire Through One Hole

Pull cables through holes but do not damage their outer jacket. The inspector will look for such damage and will make you replace all those cables before passing you wiring job. A good rule of thumb is never run more than three cables per 7/8-inch hole.

Mistake Number Five: Do Not Stuff Too Many Wires In A Device Box or Junction Box

The number of wires that you can have in a device box or junction box depends on a number of factors, the volume of the box, the size of the wires, and the number and type of other devices in the box. There is a mathematical method to calculating the size box required but that is beyond the scope of this article. For now the NEC have tables to help you select the right box for your wiring project. I will do an article on this subject in the near future.

Overcrowding a box causes the wires to overheat a potential fire hazard.

Mistake Number Six: Use A Junction Box (J-Box) When Extending Wiring

The made most often is installing a J-Box where it will become inaccessible without removing part of the building finish. You must install the J-Box where it will remain accessible, which is a NEC requirement. Placing a J-Box inside floors, walls, or ceilings is a code violation.

Mistake Number Seven: Do Not Cover Recessed Lighting Fixtures With Insulation

You should always read the labels before installing any electric fixture. Never cover recessed lighting fixtures with insulation unless it is IC Rated. You must keep the insulation a minimum of 3 inches away from any non-IC Rated recessed fixture to keep them from overheating and becoming a fire hazard. If you are installing non-IC Rated recessed lighting fixture in an insulated ceiling during a remodel, block the insulation so it cannot spring back to cover the fixture.

Mistake Number Eight: Running Along Or Across The Exposed Faces Of Beams

Do not run cable along or across the exposed beams unless "Guard Boards" protect them. Guard boards are boards placed on each side of the cables to protect them from damage. The safest practice is to run the cables through holes drilled in the beams when the cable run perpendicular to them and along their sides when the cable runs parallel to them.

There are many other mistakes that beginners make and the only way to avoid them is to study the NEC. The NEC is the electrician's Bible and you must study it religiously if you want to know with confidence what you can and cannot do electrically.


Paul Torri
Posted on Jul 11, 2010
Posted on Jul 11, 2010
Charlene Collins
Posted on Jul 2, 2010
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Jerry Walch
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M 5446
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