From where is boom length measured?

The correct answer is that boom length is measured from the center of the heel pin(s) to the center of the boom tip sheaves. This measurement is critical because it provides a standard reference point that ensures accuracy when determining the crane's lift capacity and operational limits.

By measuring from the center of the heel pin, which is the pivotal point where the boom connects to the crane, to the boom tip sheaves, it accounts for the actual working length of the boom in relation to the crane's structure and operational mechanics. This precise measurement is essential for load calculations and safety assessments, ensuring the crane can operate effectively within its specified limits.

Other measurements may be misleading or not applicable in practical scenarios. For instance, measuring the distance from the tip of the boom to the load does not adequately represent the complete boom length and could vary based on load position. Likewise, starting from the ground or the crane's base does not provide a uniform method for assessing boom length, as each crane model may have different configurations.