To help reduce the risk of lifting accidents, it’s critical to understand the role of working load limits (WLL) and how they help inform workplace safety.

The Role of Load Limits in Reducing Risk

Load limits refer to the specific weight that lifting devices, such as cranes, hoists or slings, can handle under specific conditions.

For example, the maximum breaking load (MBL) is the largest amount of weight or tension a device can handle before failing. The WLL, meanwhile, is the maximum load a device can handle when the load is uniformly pulled in a straight line. The WLL is set by the device or machinery manufacturer and is typically calculated as a ratio of the MBL. This ratio is known as the safety factor. 

Consider a hoist with an MBL of 10,000 pounds and a safety factor of 5:1, which gives a WLL of 2,000 pounds. In practice, this means the hoist could potentially lift far more than this weight safely, but to help minimize risk the WLL is capped at 2,000 pounds. 

In practice, the WLL acts as a margin of error for safety. Let’s say the hoist in our example is lifting a 2,000-pound load on a windy day. At the halfway mark of the lift, the wind suddenly gusts, applying significantly more pressure on the device — what was a 2,000-pound load now pulls down with the force of 5,000 pounds. Because the WLL is so far below the MBL, this extra load is easily handled. If the hoist is lifting the MBL of 10,000 pounds, however, the additional force could lead to device failure, putting workers at risk. 

Worth noting? The WLL isn’t simply a suggestion. According to OHSA guideline 1926.251(a)(2)(ii)², “employers must ensure that rigging equipment not be loaded in excess of its recommended safe working load as prescribed on the identification markings by the manufacturer.”

Four Best Practices to Improve Lifting Safety

While the WLL helps reduce risk, it’s not the only component in workplace lifting safety. Here are four best practices to improve protective efforts.

1. Selecting the appropriate lifting equipment

First up is selecting the right lifting equipment for the job. Key considerations include the type of object(s) being lifted, how much they way, how high they’re being lifted and where the lift is taking place.

For example, a 100-pound load being lifted onto a 10-foot shelf in a temperature-controlled warehouse poses less risk than a 4,000-pound load being hoisted 10 stories up in a large-scale construction site. In the case of the inside life, a small forklift should suffice; bringing in a hoist or sling may not be required.

Outside, more weight and potential environmental impacts require the additional safety of a crane or hoist with an MBL far above its WLL. 

2. Perform regular inspections

Regular inspections also play a role in continued safety. While the working load limits do account for wear and tear on lifting equipment, they cannot predict sudden failures. Regular inspections can help businesses identify parts that require replacement or structural components that are showing unexpected amounts of wear and tear.

3. Ensure staff are wearing the right PPE

Despite best efforts, incidents can still occur. Companies can reduce the impact of these incidents by equipping staff with the right personal protective equipment (PPE). This may include hard hats, gloves, steel-toed boots and fall protection equipment. This gear should be regularly checked (and replaced as needed) to limit injury risk.

4. Implement proper load-handling procedures   

Even loads well within the WLL can lead to accidents if they’re not handled properly. For example, if loads aren’t well-secured on lifting devices, they could slide off or tip when loads are raised. 

To improve safety, companies need to create, document and follow proper load-handling procedures. Common components include the use of specific tools or rigging types to secure loads, multiple checks from different staff members before loads are lifted and pre-lift safety meetings that ensure all staff understand how the lift will happen and what to expect. 

Know Your Limit — And Stay Within It

Working load limits help keep staff safe and reduce the risk of costly and complicated equipment failures. By ensuring that all lifts — no matter how simple or small — align with working load limits, construction and manufacturing firms can ensure compliance with OHSA standards and create workplaces that prioritize worker safety.