If water is needed for a pad-mounted transformer fire, which combination of water specs should be used?

If water is needed for a pad-mounted transformer fire, which combination of water specs should be used?

• A. 5 degree fog, 150 psi, 10 feet away, NO foam
• B. 30 degree fog, 100 psi, 33 feet away, NO foam
• C. 45 degree fog, 80 psi, 20 feet away, Foam recommended
• D. 30 degree fog, 120 psi, 33 feet away, NO foam

Answer: (B)

The key idea is to cool and knock down the fire on an energized pad-mounted transformer with a pattern that covers the area without forcing water into electrical openings. A medium fog pattern around 30 degrees provides a broad, controllable spray that absorbs heat effectively and blankets the transformer, rather than a narrow jet that can punch into crevices or splash onto live parts. About 33 feet of distance keeps firefighters out of the most dangerous arc path and away from potential oil spray, while still allowing the water to reach and cool the unit well. A pressure around 100 psi strikes a balance between sufficient reach and good atomization without creating an overly forceful stream that could cause splashing or debris to be driven into openings. Foam isn’t necessary here because the priority is rapid cooling of the transformer oil and surface, and foam can complicate operations around energized electrical gear. In this context, the chosen combination provides effective cooling, safe distance, and manageable application without introducing unnecessary materials or risks.

The key idea is to cool and knock down the fire on an energized pad-mounted transformer with a pattern that covers the area without forcing water into electrical openings. A medium fog pattern around 30 degrees provides a broad, controllable spray that absorbs heat effectively and blankets the transformer, rather than a narrow jet that can punch into crevices or splash onto live parts. About 33 feet of distance keeps firefighters out of the most dangerous arc path and away from potential oil spray, while still allowing the water to reach and cool the unit well. A pressure around 100 psi strikes a balance between sufficient reach and good atomization without creating an overly forceful stream that could cause splashing or debris to be driven into openings. Foam isn’t necessary here because the priority is rapid cooling of the transformer oil and surface, and foam can complicate operations around energized electrical gear. In this context, the chosen combination provides effective cooling, safe distance, and manageable application without introducing unnecessary materials or risks.