A distance of at least blank must be maintained from a nonmetallic conduit containing a high-voltage circuit operating at 100 Hz or less.

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Multiple Choice

A distance of at least blank must be maintained from a nonmetallic conduit containing a high-voltage circuit operating at 100 Hz or less.

The key idea is keeping a safe clearance around nonmetallic conduit that contains a high-voltage circuit at power frequency to prevent arcing or tracking to nearby surfaces. At 100 Hz or less, the energized parts can cause an air breakdown or surface discharge if the gap to surrounding materials is too small, so a minimum buffer is specified. One and a half inches gives a practical margin that reduces the risk of flashover or insulation damage during installation, operation, and maintenance. Distances smaller than that are more prone to arcing, while a larger gap isn’t needed for this voltage range, so the minimum required is one and a half inches.

The key idea is keeping a safe clearance around nonmetallic conduit that contains a high-voltage circuit at power frequency to prevent arcing or tracking to nearby surfaces. At 100 Hz or less, the energized parts can cause an air breakdown or surface discharge if the gap to surrounding materials is too small, so a minimum buffer is specified. One and a half inches gives a practical margin that reduces the risk of flashover or insulation damage during installation, operation, and maintenance. Distances smaller than that are more prone to arcing, while a larger gap isn’t needed for this voltage range, so the minimum required is one and a half inches.

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