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Electrician Red Seal · Question

An industrial facility is being upgraded, and a new 400 A main service entrance conductor is to be installed. The conductors are 500 kcmil (MCM) copper, insulated with RW90, and installed in a single conduit. The ambient temperature is 30°C (86°F), and there are no more than 3 current-carrying conductors. Based on CEC Table 2, what is the maximum ampacity of these conductors after applying the appropriate correction factors?

According to CEC Table 2, a 500 kcmil copper conductor with 90°C (194°F) insulation has an ampacity of 435 A when not more than three conductors are in a condui

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Question: An industrial facility is being upgraded, and a new 400 A main service entrance conductor is to be installed. The conductors are 500 kcmil (MCM) copper, insulated with RW90, and installed in a single conduit. The ambient temperature is 30°C (86°F), and there are no more than 3 current-carrying conductors. Based on CEC Table 2, what is the maximum ampacity of these conductors after applying the appropriate correction factors?

Answer options:

  • 380 A
  • 400 A ✅ 435 A
  • 455 A

Correct answer: 435 A

Explanation: According to CEC Table 2, a 500 kcmil copper conductor with 90°C (194°F) insulation has an ampacity of 435 A when not more than three conductors are in a conduit (Column 4). No adjustment factor for ambient temperature is needed as the temperature is 30°C (86°F).

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