What is the maximum spacing allowed for roof bolts under normal conditions?

The correct answer reflects the standard practices in mine safety and roof support design. Under normal conditions, the maximum spacing allowed for roof bolts, which are critical for maintaining the stability of mine roofs, is generally set at 4 feet. This distance allows for adequate support and helps ensure that the roof remains secure, reducing the risk of collapses or accidents in active mining areas.

By spacing the bolts at this interval, it provides a sufficient number of anchors in the roof structure to distribute loads evenly and address any potential weaknesses that might lead to failures. This spacing is designed to conform with safety regulations and engineering standards that are essential for protecting miners and maintaining safe working conditions underground.

Other options suggest larger spacings, which may not provide sufficient support or safety margin in typical operating conditions, thereby increasing the risk of roof falls and endangering workers. Adhering to the 4-foot spacing is a crucial aspect of mine operation safety protocols.