NEIEP Machine Room Maintenance (550) Practice Test

Which statement about carbon dust in electrical equipment is accurate?

It is harmless and can be ignored. It improves electrical conductivity permanently. It should be cleaned using high-pressure water jet. It can form conductive paths that increase arcing risk and should be removed safely.

Correct Answer:

It can form conductive paths that increase arcing risk and should be removed safely.

Explanation:

Carbon dust inside electrical gear is not harmless. It can become conductive, especially when moisture is present, and it can create conductive paths along surfaces or between conductors. Those paths increase the risk of arcing, tracking, and short circuits, which can damage equipment or start a fire. Because of this, the dust needs to be removed carefully and safely, with the equipment fully de-energized and isolated. Use methods that prevent dispersing the dust or introducing moisture, such as a vacuum with a HEPA filter or a damp, non-conductive wipe, and avoid dry brushing, compressed air, or high-pressure water jets inside the equipment. Following proper cleaning procedures helps restore insulation integrity and reduce arcing risk.

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