Under what condition must motor vehicles be equipped with turn indicator lamps?

Motor vehicles are required to be equipped with turn indicator lamps particularly when the body or load extends 24 inches or more to the left of the corner. This regulation is critical for ensuring safety on the road, as it enhances visibility to other drivers about the vehicle's intention to turn or change lanes, especially when the vehicle extends beyond its normal width. Turn indicator lamps serve the purpose of signaling to other road users, reducing the risk of accidents that could occur due to an unexpected maneuver from a wider vehicle.

While indicating a turn to the left might seem intuitively correct, it does not encompass the complete perspective on when these lamps are necessary. Additionally, conditions like bad weather or being on highways do not specifically pertain to the requirement for turn indicator lamps in the way this particular context outlines. The regulation focuses on the dimensions of the vehicle and how they relate to proper signaling, making the condition regarding the vehicle's extension paramount for compliance.