May 20, 2016  Does Spray Foam Insulation Affect Electrical (or Other) Work in the Attic? May 20, 2016. While there may be debate between individual contractors about spraying foam insulation over electrical wires, industry guidelines state that spray foam insulation can be applied directly over electrical wiring. If you're familiar with wiring, first cut the power to your attic light and then connect Romex wire that's been stripped of about 8 inches of covering at the end to an available knockout in the junction box. Then, run the wiring to your attic fan, strip another 8 inches at that end, and connect the wire to the thermostat.

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Installing an electrical junction box or J-box in the attic is not much different from installing a J-box anywhere else. The same basic National Electric Code or NEC rules apply. Installing a J-box in the attic is easiest if the attic is unfinished and used for nothing more than storage. As with any electrical project where new devices and wiring is to be installed, you will need to get a wiring permit before you begin work and have your work inspected just as a professional electrician would.

1. Turn off the all the circuit breakers supplying power to the cables where the J-box is to be installed. Use the noncontact voltage tester to make sure you have turned off the correct circuit breakers before cutting the cables. Before cutting, label the cables with a marker so you will know which wires to splice together inside the J-box.

2. Mount the J-box to the side of a framing member, such as a wall stud, ceiling rafter or floor beam using two #8 by 1-inch wood screws. Mount the box in such a way that all the cables entering and leaving the box will be set back at least 1 ¼ inches from the face of the stud, rafter or beam. This 1 ¼ inch set-back is required by the NEC to protect the cables from damage by nails or screws. Install one cable connector in the box for each cable entering or leaving the box. Also do not place the box where it will be later covered with insulation or concealed in any other manner. The NEC requires that a J-box be accessible at all times.

3. Install the cable ends in the J-box. Slide the ends of the cables through the cable connectors until the they extend 6 inches from the front of the box. Secure the cables in place by turning the cable connector's clamping screws in a clockwise direction.

4. Remove the outer jacket from the cable ends using the cable ripper or a utility knife. Remove ¾ inches of insulation from the ends of the black and the white insulated wires. Be careful when stripping the insulation from the wires that you use the proper notch on the wire strippers.

5. Connect all the bare ground wires together inside the box using a wire nut. Download the price is right wii iso. To make the connection, hold all the wire ends side by side and screw on the wire nut. Splice the stripped ends of the black (hot) wires together in the same manner, then the white (neutral) ones. Make sure that you double check your markings on the cables to be sure you have connected the right wires together in the box.

6. After your work has been inspected, you can put the box cover in place and return the circuit breakers to their on position.

Things You Will Need

• Noncontact voltage tester

• 4-inch-square junction box with blank cover

• 3/8-inch drill-driver with Phillips screwdriver bit

• Hammer

• Nonmetallic sheathed cable staples

• Cable connectors

• Wire cutters

• Cable ripper or utility knife

• Wire strippers

• Plastic wire nuts

About the Author

Based in Colorado Springs, Colo., Jerry Walch has been writing articles for the DIY market since 1974. His work has appeared in “Family Handyman” magazine, “Popular Science,” 'Popular Mechanics,' “Handy” and other publications. Walch spent 40 years working in the electrical trades and holds an Associate of Applied Science in applied electrical engineering technology from Alvin Junior College.

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Supporting a ceiling fan properly is important to avoid personal injury and damage to your house. There are several acceptable ways to support a ceiling fan, including special boxes designed with straps or fastening the box to wood blocking. A visual inspection from above is always recommended to confirm that the previous work is sufficient. If there is no attic space available to use for inspection, other options are available.

Support Requirements

The National Electric Code requires that all fans 35 pounds and over must be supported with an outlet box or outlet box system that is listed for ceiling fan support. The manufacturer must have marked the outlet box system to indicate that it is acceptable for ceiling fan installations. If the original box is not listed for this purpose, it must be retrofitted and attached securely to the building structure.

Outlet Boxes Designed for Ceiling Fans

Specially designed outlet boxes for ceiling fan support have special braces that extend to contact adjacent ceiling joists. These braces are then nailed or screwed into the joists themselves. A threaded set-nipple is mounted in the middle of the box, which allows the box to travel laterally along the brace. Inspecting the brace-joist connection is the best way to make sure that the box was installed properly.

Wooden Support

Ceiling boxes in older homes may not have special fan boxes. Instead, the carpenters who framed the ceiling may have added a block between the ceiling joists upon which the box is mounted. The box should have been fastened with screws to the bottom of the block. If the box is mounted on only one side or with nails it should not be used as is.

Inspecting an Existing Box

The best way to confirm that a box is securely attached is to inspect from above. Crawling through the attic to locate the box allows you to confirm that all supports are adequate. However, if you are installing a fan between stories where there is no attic space, you will have to determine from below. Look for the attachment points of the box. Is it screwed to wood from the sides, or do the screws go through the top of the box? Is there a threaded nipple visible from below? If you cannot discern how the box is supported, hire an electrician to inspect the box for you.

References (1)

• 2011 National Electric Code; National Fire Protection Association

Resources (1)

• Old Electrical Wiring: David Shapiro

About the Author

Charles W. St.Clair has been writing professionally since 2003. He lives in Oakland, Calif., working as an electrician and carpenter. St. Clair holds a bachelor's degree in public policy from Emory & Henry College and a master's degree in city planning from University of North Carolina-Chapel Hill, where he specialized in food system planning.