Trench shield
Encyclopedia
Trench shields are steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...

 or aluminum structures used for protecting utility workers while performing their duties within a trench
Trench
A trench is a type of excavation or depression in the ground. Trenches are generally defined by being deeper than they are wide , and by being narrow compared to their length ....

. They are customarily constructed with sidewalls of varying thicknesses held apart by steel or aluminum spreaders. Spreaders can be interchanged to match the width of the trench. The different materials and building designs lead to a variety of depth ratings, i.e. the depth of a trench that the shield can withstand a collapse without buckling. Depth ratings are determined by registered professional engineer
Professional Engineer
Regulation of the engineering profession is established by various jurisdictions of the world to protect the safety, well-being and other interests of the general public, and to define the licensure process through which an engineer becomes authorized to provide professional services to the...

s.

A shield should not be confused with a shore. While they may serve the same function, trench shoring
Trench shoring
Trench shoring is the process of bracing the walls of a trench in order to prevent collapse. The phrase can also be used as a noun to refer to the materials used in the process....

 is a different physical application that holds up the walls of a trench to prevent collapse.

In the US, use of a trench shield is governed by OSHA
Occupational Safety and Health Administration
The United States Occupational Safety and Health Administration is an agency of the United States Department of Labor. It was created by Congress of the United States under the Occupational Safety and Health Act, signed by President Richard M. Nixon, on December 29, 1970...

29 CFR Part 1926.650-.652 Subpart P-Excavations
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