Utilities are discovering that switchgear box pads made of polymer concrete are easier to install, stronger and last longer than traditional concrete box pads.

Strongwell, the manufacturer of QUAZITE underground utility vaults and cabinet pads made of precast polymer concrete, is also finding that utilities love the switchgear box pads because they are lighter than the regular precast concrete alternative, so extra equipment is not needed for installation. They have three to five times the compressive, flexural and tensile strengths compared to traditional concrete enclosures, and they are also highly resistant to corrosion so their life cycle is extended.

Arizona Public Service (APS; Phoenix, Arizona, U.S.) uses nearly 500 QUAZITE switchgear box pads per year for electrical service to new housing developments and industrial parks. The lightweight box pad can be set in place with the backhoe used to dig the hole (precast concrete pads this size would require a crane to lift and install).

The polymer concrete switchgear box pad has become part of the APS standards for easier, quicker and less expensive installations throughout its service area, which encompasses metropolitan Phoenix, Flagstaff, Prescott and Yuma, Arizona.

The box pad also provides a larger underground area with more room to “train” the cable into the switch-gear. This makes it a lot easier and quicker for APS to install the switchgear. APS uses pad mount switchgears and had previously been bolting the cabinets to a flat precast concrete pad.

APS knew it needed an underground vault area to make it easier to connect the cables. Stongwell's box pad accommodated this need and combined the functions of an underground vault and a cabinet pad. The box pad is specifically designed for the PME 6-12 cabinets made by S&C Electric. The 36-inch-deep box pad measures 89.25 by 87.25 inches on the bottom and tapers to a 76- by 74-inch size at the top. The top of the box pad can be bolted directly onto the box pad during the installation.

What is Polymer Concrete?

Polymer concrete is made from selectively graded aggregates in combination with a polymer resin system. When combined through a process of mixing, molding and curing, an extremely powerful cross-linked bond is formed. Precast polymer concrete is reinforced with fiberglass for exceptional strength and rigidity.

Design Possibilities

Another benefit of polymer concrete is the ability to precast enclosures according to the customer's specifications. Years of experience enable Strongwell's engineers to produce custom-designed parts to user specifications. Standard sizes for monolithic enclosures are available up to 4 by 8 by 4 ft. Pads for cabinets or equipment enclosures are currently being made as small as 25 by 38 inches, as large as 93 by 93 inches and even larger when bolted together. If other sizes are required, the Strongwell service department will work directly with the user to meet his or her needs. Because system requirements vary by utility, QUAZITE switchgear box pads can be outfitted to accommodate a variety of racking and struts, knockouts and holes. Additional accessories such as terminators, gaskets, pulling eyes and other options are possible.

Safety

The safety of ASP's field personnel is always number one. In the case of selecting switchgear box vaults and pads, there is peace of mind in knowing that polymer concrete box pads have less than 1% water absorption, are nonflammable and are nonconductive so grounding of the box pad is not required.

For more information, visit www.strongwell.com.