10 foot long planks used on scaffolding should not extend over the edges of the support more than:

In general construction practices, particularly concerning scaffolding safety, there are specific guidelines regarding how much a plank can extend beyond its support to ensure stability and prevent accidents. The correct answer, which states that planks should not extend over the edges of the support more than 12 inches, is based on safety protocols that aim to balance load distribution and maintain a secure working platform.

When a plank extends too far beyond its support, it becomes prone to tipping, which increases the risk of falls and injuries. Limiting the extension to 12 inches ensures that the majority of the plank remains securely supported, allowing for safe access and use. This regulation helps maintain structural integrity and worker safety on scaffolds, aligning with best practices in construction environments.

The incorrect options do not meet the safety standards typically observed in the industry, which require a balance between functionality and the safety of workers. By adhering to the 12-inch extension limit, contractors can mitigate risks associated with overextension on scaffolding.