What is the RECOMMENDED bend radius of a conduit with an internal diameter of 51 mm (2 in)?

Question

Options

• A203 mm (8 in)
• B305 mm (12 in)
• C406 mm (16 in)
• D508 mm (20 in)

• A
  7% (3)
• B
  2% (1)
• C
  13% (6)
• D
  78% (35)

Explanation

For conduit with a 2-inch (51 mm) internal diameter, the recommended minimum bend radius is 10 times the internal diameter: 10 x 51 mm = 510 mm, which rounds to 508 mm (10 x 2 in = 20 in), making D correct. Options A (203 mm/8 in), B (305 mm/12 in), and C (406 mm/16 in) represent multipliers of approximately 4x, 6x, and 8x respectively - all below the industry-standard minimum and would place excessive stress on cables pulled through the conduit, risking insulation damage. The 10x rule exists to ensure cables can be pulled through without exceeding their minimum bend radius ratings and to reduce pulling tension.

Memory tip: "Ten times the inside" - whatever the internal diameter of the conduit, multiply by 10 to get the recommended bend radius. For a 2-inch conduit, that is 20 inches; for a 4-inch conduit, it would be 40 inches.

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