Repair An Outdoor Light Fixture

Dear Mr. Electrician:  How do I repair an outdoor light fixture that is not mounted correctly on the front of my house?

Answer:  You can repair an outdoor light fixture mounting problem sometimes by using a siding box.  They are available in a few styles to accommodate various sizes of siding on a house.  NOTE: Some text links below go to applicable products on Amazon.

Below are photos from a repair of an outdoor light fixture with a funky electrical box mount that I corrected for a client by using a siding box.

REPAIR AN OUTDOOR LIGHT FIXTURE

Side view of an outdoor light fixture mounted to an indoor electrical box that is covered with duct tape and caulk
Side view of an outdoor light fixture mounted to an indoor electrical box that is covered with duct tape and caulk

When I first saw the above outdoor light fixture mounted this way I had no idea what to expect.  I had to use my razor knife to cut into the white blob behind the outdoor light fixture and discovered duct tape beneath.

Side view of an outdoor light fixture mounted to a surface mounted indoor electrical box
Side view of an outdoor light fixture mounted to a surface mounted indoor electrical box

The outdoor light fixture was attached to the outside wall using a metal, surface mounted, indoor, octagonal electrical box that was wrapped in duct tape and covered in caulk.  This was not a good method for attaching an outdoor light fixture to a building.

Normally a pancake electrical box would be mounted to the surface of the Oriented Strand Board (OSB) sub-surface and the outdoor light fixture would be attached to that.  The vinyl siding would be cut around the pancake box.

Though a pancake box is shallow, the National Electrical Code (NFPA 70) approves its use because the cubic inches of space inside of the outdoor light fixture canopy (Indoor light fixtures also) is allowed to be included when calculating the number of wires permitted.

However, a pancake box does not always provide a good solid level surface to support the light fixture.  This varies by the surface of the wall of course.

The old light fixture, duct tape, and caulk is removed to reveal an indoor electrical box with some of the knockouts removed
The old light fixture, duct tape, and caulk is removed to reveal an indoor electrical box with some of the knockouts removed

The octagonal indoor electrical box had two of its knockouts removed and was covered with duct tape and caulk.  In addition to being awkward looking it was clearly not an approved weatherproof arrangement, even with the caulking.

The old metal box was not grounded as required in article 250 in the National Electrical Code (NFPA 70).

Wires for old outdoor light fixture sticking out from the vinyl siding
Wires for old outdoor light fixture sticking out from the vinyl siding

My guess is that there was a pancake box installed originally when the townhouse was built, but for some reason it was removed.  I had to use a razor blade scraper to remove the bulk of the caulk that had adhered to the vinyl siding.

Fortunately the type NM electrical cable was in good working condition.  I removed the two-screw metal clamp type Romex connector and used the plastic button type connector that was packaged with the plastic siding box.

A siding box is used to mount an outdoor light fixture on vinyl siding
A siding box is used to mount an outdoor light fixture on vinyl siding

A siding box is an excellent method of supporting an outdoor light fixture on vinyl siding and other surfaces.  I have used them many times to repair an outdoor light fixture installation.

In addition to siding boxes, there are also siding blocks available which do not contain a built-in electrical box.  Siding blocks work with other electrical boxes to help level and trim outdoor light fixtures.

FINISHED REPAIR OF AN OUTDOOR LIGHT FIXTURE

The completed repair and replacement of an outdoor light fixture
The completed repair and replacement of an outdoor light fixture

The #8141DBL siding box keeps the light fixture level and helps to prevent it from indenting the vinyl siding.

The completed repair and replacement of the electrical box and outdoor light fixture
The completed repair and replacement of the electrical box and outdoor light fixture

The siding box used to repair an outdoor light fixture here is made by Arlington Industries and their entire line of siding boxes can be seen by clicking on this link.

My post about light switch wiring diagrams may be helpful when doing this type of work.