Installing Electrical Enclosures Adjacent to Roadways

The QUAZITE® H20 enclosures include a rugged polymer concrete box with a galvanized steel frame and cover surrounded by a minimum of 3 inches of cast-in-place concrete. For scenarios that could benefit from this type of enclosure, read our blog.

When is a roadway like a bridge? Any underground structure or enclosure essentially functions like a small bridge when placed in or near a roadway. The H20 specification (pronounced H-twenty), designed for highway bridges, functions in this application. Enclosures that meet H20 are great for settings that experience vehicular traffic such as loading zones, parking facilities or roadside utilities.

The H20 material spec is published by the American Association of State Highway and Transportation Officials (AASHTO, pronounced Ash-toe). Different from the ANSI tier rating, it dictates the load and type of materials. Boxes used near roadways are often built of precast concrete.

Quazite H20 Enclosure Blog

By contrast, QUAZITE® H20 enclosures include a rugged polymer concrete box with a galvanized steel frame and cover surrounded by a minimum of 3 inches of cast-in-place concrete.

Proper installation for H20 enclosures is different from standard Tier 22 QUAZITE enclosures. The concrete element is critical because it is required to meet the H20 specification. To aid installation, inspection holes in the steel frame allow the contractor to ensure proper flow of concrete under the frame.

Some transportation departments around the country, such as CalTrans (the California Department of Transportation), do not accept Tier 22 boxes. Under heavy loading conditions, Tier 22 boxes can wear down after years of service. This makes long-lasting H20 boxes a preferred alternative.

Let’s look at a couple scenarios that could benefit from this type of enclosure.


A building contractor is working on a Department of Transportation project, such as a new road or road widening. After reviewing the project specifications, it is determined that 100 boxes are required for placement directly adjacent to the roadway. The specification lists the box size and depth, noting a load rating of H20. The contractor’s purchasing team calls a local distributor for recommendations, such as the QUAZITE H20 boxes.

Parking Lot

The purchasing manager for a building contractor reviews the specifications for a private construction job, a new convention center. The contractor will need 100 boxes for placement around the center. The boxes have varying load requirements but all of them include ANSI/SCTE tier ratings, such as Tier 22. Some of these boxes will be placed in the parking lot, directly in the wheel path of traffic. The manager calls the local distributor for recommendations. The distributor quotes several tier-rated boxes and includes QUAZITE H20 boxes as a good choice for high-traffic areas.


Properly installed, Quazite H20 enclosures will offer many years of strength, protection and tamper resistant utility protection. Watch our new, animated installation video to see exactly how Quazite H20 enclosures are installed from start to finish. 



Designed to provide service in potentially heavy traffic areas outside roadways, these boxes provide specifying engineers a superior alternative to Tier 22 enclosures.

Please reach out to your Hubbell sales rep or call 800.346.3062 to find out more about QUAZITE H20 boxes.


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