Mistake 1: Making Connections Outside Electrical Boxes

Making Connections Outside Electrical Boxes

Mistake: No electrical box

Never connect wires outside of electrical boxes. Junction boxes protect the connections from accidental damage and contain sparks and heat from a loose connection or short circuit.

Solution: Add a box

The connection is not contained in an electrical box, which houses a box and connection wires. This photo shows a method of installing an external light on a wood wall panel. When you consider upgrading your outdoor security lighting.

Mistake 2: Cutting Wires Too Short

Cutting Wires Too Short

Mistake 2: Wires too short

Wires that are cut too short make wire connections difficult and—since you’re more likely to make poor connections—dangerous. Leave the wires long enough to protrude at least 3 in. from the box.

Solution: Extend wires


If you run into short wires, there’s an easy fix. Simply add 6-in. extensions onto the existing wires. The photo shows a type of wire connector that’s easier to install in tight spots. You’ll find these in hardware stores and home centers.

Mistake 3: Leaving Plastic-Sheathed Cable Unprotected

Leaving Plastic-Sheathed Cable Unprotected

Mistake: Unprotected cable

It’s easy to damage plastic- sheathed cable that’s left exposed between framing members. That’s why the electrical code requires cable to be protected in these areas. Cable is especially vulnerable when it’s run over or under wall or ceiling framing, as shown here.

Solution: Install a 2 x 2

Protect exposed plastic- sheathed cable by nailing or screwing a 1-1/2-in.-thick board alongside the cable. You don’t have to staple the cable to the board. Running wire along a wall?

Mistake 4: Poor Support for Outlets and Switches

Poor Support for Outlets and Switches

Mistake: Loose outlet

Loose switches or outlets can look bad, but worse yet, they’re dangerous. Loosely connected outlets can move around, causing the wires to loosen from the terminals. Loose wires can arc and overheat, creating a potential fire hazard.

Solution: Add rigid spacers

Fix loose outlets by shimming under the screws to create a tight connection to the box. You can buy special spacers like we show here at home centers and hardware stores. Other options include small washers or a coil of wire wrapped around the screw.

Mistake 5: Installing a Three-Slot receptacle without a Ground Wire

Installing a Three-Slot receptacle without a Ground Wire

Solution: Install a two-slot outlet

If you have two-slot outlets, it’s tempting to replace them with three-slot outlets so you can plug in three-prong plugs. But don’t do this unless you’re sure there’s a ground available. Use a tester to see if your outlet is grounded. A series of lights indicates whether the outlet is wired correctly or what fault exists. These testers are readily available at home centers and hardware stores.

If you discover a three-slot outlet in an ungrounded box, the easiest fix is to simply replace it with a two-slot outlet as shown. Dead outlet?

Mistake 6: Recessing Boxes Behind the Wall Surface

Recessing Boxes Behind the Wall Surface

Mistake: Exposed combustible material

Electrical boxes must be flush to the wall surface if the wall surface is a combustible material. Boxes recessed behind combustible materials like wood present a fire hazard because the wood is left exposed to potential heat and sparks.

Solution: Add a box extension

The fix is simply to install a metal or plastic box extension. If you use a metal box extension on a plastic box, connect the metal extension to the ground wire in the box using a grounding clip and a short piece of wire.

Mistake 7: Installing Cable Without a Clamp

Installing Cable Without a Clamp

Mistake: Missing clamp

The protection of the cable can be strained to the connection. In the case of metal, sharp edges can be reduced by insulated wires. A single plastic box does not require an internal cable clamp, but the cable must be nailed to 8. Of the box. Requires a larger plastic box with built-in cable clamps and cables that must be nailed to 12. Of the box. The cable must be connected to a metal box explosion proof cable clamp.

Solution: Install a clamp

Make sure the sheathing on the cable is trapped under the clamp, and that about 1/4 in. of sheathing is visible inside the box. Some metal boxes have built-in cable clamps. If the box you’re using doesn’t include clamps, buy clamps separately and install them when you add the cable to the box.

Mistake 8: Overfilling Electrical Boxes

Overfilling Electrical Boxes

Mistake: Box too small

Too many wires stuffed into a box can cause dangerous overheating, short-circuiting and fire. The National Electrical Code specifies minimum box sizes to reduce this risk.

Solution: Install a larger box

To figure the minimum box size required, add up the items in the box:

1 – for each hot wire and neutral wire entering the box

1 – for all the ground wires combined

1 – for all the cable clamps combined

2 – for each device (switch or outlet—but not light fixtures)

Multiply the total by 2.00 for 14-gauge wire and by 2.25 for 12-gauge wire to get the minimum box size required in cubic inches. Then choose a box with at least this much volume. Plastic boxes have the volume stamped inside, usually on the back. Steel box capacities are listed in the electrical code. Steel boxes won’t be labeled, so you’ll have to measure the height, width and depth of the interior. Then multiply to find the volume.

Mistake 9: Reversing Hot and Neutral Wires

Reversing Hot and Neutral Wires

Solution: Identify the neutral terminal

The connection to the black filament terminal leads to a potentially fatal shock. The trouble is that you may not realize the error until someone is shocked because the lights and most other plug-in devices will still work; they just will not work safely.

Always white wires are connected to the neutral terminal outlets and fixtures. Terminals are always visible. Usually made of silver or light colored screws. The hot wire is connected to another terminal. If there is a green or bare copper wire, ground. Ground to a green ground screw or to a ground or ground box.


Mistake 10: Wiring a GFCI Backward

Wiring a GFCI Backward

Solution: Connect power to the “line” terminals

GFCI (Ground Fault Circuit Breaker) media protects you from a fatal blow, turning off the power when they feel there are subtle differences in the current. They have two dual terminals. A pair, labeled “Line”, is the power of the GFCI export itself. Another set of tags is “loaded” and protected for downstream channels. You will lose the impact protection if you connect the line to the load.