Let it burn. Burning electrical equipment is already ruined and will be replaced. Contact the local utility and wait for them to arrive.
Evacuate the area. Keep people at least 300 feet away. Protect exposures to prevent fire from spreading.
If an equipment fire must be suppressed, utility personnel and your incident commander will tell you how to proceed.
Successful Response to Substation Fire
A circuit breaker containing 20 gallons of mineral oil caught fire and exploded at a rural electric substation. Flames and smoke shot 200 feet into the air. Firefighters evacuated nearby residences within 300 feet, set up a 100-foot perimeter around the substation, closed the nearby highway, and let the fire run its course. Thanks to proper response procedures, no one was injured.