When a scissor lift is stationary and being used at height is there any code that requires the area to be cordoned off?

OSHA doesn’t directly call out cordoning off the area around a scissor lift, but the expectation is there. OSHA standards 29 CFR 1910.29 (General Industry) and 1926.451 (construction) require that you protect employees from falling objects. This is typically captured in the toe board around the bottom of the lift, which prevents objects from being knocked off the lift. Whenever employees are using tools or other objects that could fall from their hands or the lift, employees below need to be protected from falling objects. Any employees who enter the area would need awareness of the work going on and head protection.

A best practice, barricade the fall distance of 125% lift radius. If the lift was going 20 feet up, barricade 25 feet around the lift. This protected employees from falling objects and the chance that the lift could be bumped by another vehicle or otherwise be tipped over.