What is secondary retention?

Secondary retention is an additional, independent method of securing an object so that it is prevented from falling if its primary fixing or attachment fails.

It is an important part of dropped object prevention (DROPS), particularly when equipment is installed or used at height, offshore, or in environments where a falling object could cause injury or damage.

A simple example

Imagine a light fitting mounted to a ceiling or structure.

• Primary retention: The bolts, brackets or mounting system hold the light in position.
• Secondary retention: A separate retention wire or retention net connects the light to a suitable structural attachment point.

If the primary mounting fails, the secondary retention system is designed to help arrest the equipment and prevent it from falling.

Why is secondary retention important?

Primary fixings can fail for many reasons, including:

• Vibration
• Corrosion
• Fatigue
• Incorrect installation
• Loose fixings
• Mechanical damage
• Deterioration over time

Secondary retention provides an additional layer of protection against the consequences of such a failure.

It is particularly relevant to:

•  Oil & gas facilities
•  Offshore installations
•  Wind turbines
•  Construction
• Industrial maintenance
•  Marine environments
•  Industrial facilities
•  Working-at-height applications

Secondary retention vs tool tethering

These are related, but they aren't the same thing.

Tool tethering generally secures a tool being carried or used by a person working at height — for example, attaching a spanner to a worker using a tool lanyard.

Secondary retention is more commonly used to secure installed equipment, fixtures, components or other objects independently of their primary fixing.

For example:

Spanner - tool lanyard - worker

versus:

Light fitting - primary fixing - independent retention wire - structure

What can secondary retention secure?

Depending on the application and the engineered system, secondary retention can be used for items such as:

• Light fittings
• Cameras
• Electrical equipment
• Instrumentation
• Panels
• Covers
• Small components
• Signs
• Brackets
• Other equipment installed at height

The retention system needs to be appropriately selected for the equipment, attachment points, environment and potential load. It shouldn't simply be assumed that any wire or net is suitable for any application.