On construction sites, incandescent bulbs require what?

The requirement for incandescent bulbs on construction sites to be guarded unless deeply recessed reflects the need for ensuring safety in potentially hazardous environments. Guarding the bulbs helps protect them from impact, which can cause breakage and lead to electrical hazards or fire risks. Construction sites are often bustling with activity, and heavy equipment or materials can easily come into contact with lighting fixtures. By requiring guarding, the risk of accidents due to broken bulbs is mitigated, enhancing the overall safety of the work environment.

In contrast, other options may not adequately address the safety hazards associated with exposed lighting. Leaving bulbs exposed can lead to various safety risks, while the requirement for bulbs to be positioned higher than 10 feet does not universally apply to all situations, as lower placements may still need guarding. Similarly, while shielding with plastic covers can enhance safety in some scenarios, it doesn't replace the necessity of guarding as a primary means of protection against impact. Overall, the focus is on preventing incidents related to breakage and securing fixtures in active work zones.