In numerous applications, a light fixture will need to be attached to
concrete. The use of a wedge anchor is suitable for this type of
application. Wedge anchors
are designed for use in solid concrete and have the highest, most
consistent holding values of any mechanical type concrete fastener. The
wedge anchor is easy to install and is available in standard zinc
plating, hot dipped galvanized and stainless steel for outdoor
The size of the hole(s) in the light fixture will determine the
size of the wedge anchor that should be used. When using a wedge anchor,
the hole size to be drilled into the concrete should be equal to the
diameter of the wedge anchor. The hole in the light fixture needs to be
slightly larger than the diameter of wedge anchor being used. For
example, if the hole in the light fixture is 5/16" then a 1/4" wedge
anchor should be used.
The length of the wedge anchor to be used can be determined by
adding the thickness of the material being fastened to the minimum
embedment for the diameter of anchor being used plus any space needed
for the nut and washer. This will provide the minimum length of anchor
to be used. Generally, the best holding values are obtained with deeper
embedment into the base material. However, the deeper the concrete is
penetrated, the more likely that rebar may be encountered during
installation. If the light fixture is to be placed outdoors, stainless
steel wedge anchors should be used since stainless steel is rust
Below are step by step instructions outlining how to use wedge anchors to fasten a light fixture to concrete:
1. Place the light fixture on the concrete. Mark where these
holes are on the concrete. You can also use the light fixture as a
template and hold it in place and then drill these holes. Either method
2. When drilling into concrete, always use a hammer drill. Using a
hammer drill is the most effective way to ensure that the hole size for
the concrete fastener is accurate, which is critical for obtaining
3. Once the holes are drilled, clean out any debris that was
created during the drilling process using a wire brush, vacuum or
4. Place the nut and washer on the end of the wedge anchor to protect the threads during installation.
5. With the light fixture in place, insert the wedge anchor
through the holes in the fixture and into the concrete. Tap lightly
until a minimum of 6 threads is below the surface of the light fixture.
6. Hand tighten the nut until snug.
7. With a wrench, turn the nut 3-4 times until tight or until it
meets the recommended torque value for the diameter of wedge anchor
When installing and fastening light fixtures into concrete, a wedge anchor
is an excellent choice due to its consistent holding values, easy
installation and variety of material types that are available.
As with any anchoring project, it is important to keep safety in mind and follow instructions carefully. Always remember to wear safety goggles, handle all tools with extra care and follow all technical specifications. This article is meant to serve only as a basic explanation of concrete fasteners. Always refer to manufacturer's instructions or consult a contracting expert during any anchoring project.
Article Written By:
Bob Carlisle, President of Concrete Fasteners
Concrete Fasteners, Inc. has over 40 years of experience selling concrete fasteners. We can ship out one box or a whole pallet of concrete anchors. Our products are of the highest quality... "your satisfaction is guaranteed". We ship all orders the same day the order is received.