Final answer:
During an electrical storm, it is essential to evacuate the blast area, disconnect blast circuits if possible, and ensure all personnel are at a safe distance. Preventive measures like lightning rods and correct rating of electrical equipment should be used to mitigate risks of premature detonation and overheating.
Step-by-step explanation:
When an electrical storm approaches a blast hole pattern that has been tied-in with detonating cord and surface relays, extreme caution must be exercised due to the possibility of electric fields induced by the storm interacting with the blasting apparatus. Variations in electric fields can be larger and even reversed in direction during storm conditions, posing a risk of premature detonation. To safeguard against this, the area should be evacuated, tied-in blasting circuits should be disconnected if possible, and all personnel should maintain a safe distance until the storm passes. Additionally, it is crucial to ensure that lightning rods and other preventive measures are correctly employed to prevent charge buildup on structures near the blast area.
Working with high-power electric circuits during a storm poses several hazards. The use of insulating gas in circuit breakers, for example, helps to extinguish sparks that can occur during the interruption of high-voltage electricity flow. Moreover, electrical equipment and systems should be appropriately rated to prevent overheating and the thermal hazard should be managed using circuit breakers or fuses to prevent excessive currents.