A Sudoku with a difference, solve the clues, then solve the puzzle!.

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Ten minutes = Good work, your hired!

Fifteen minutes = OK not too bad.

Twenty minutes = when shall we book you in for a course?

 C
 D
 H
 B
 A
 F
 E
  I
 B
 C
 G
 D
 D
 B
 A
 G
 A
 D
 G
  I
 A
 E
 B
 H
  I
 H
 E
 D
 C
 B
 D
 F
 F
  I
 C
 B
A = nominal rating in Amperes for a standard domestic lighting circuit mcb.
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B = this part of BS7671 details special locations and installations.
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C = IPX ? is suitable for permanent submersion.
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D = number of live conductors in a standard radial circuit.
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E = approximate tabulated Zs value for a 5A BS3036 for a 0.4s disconnection time.
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F = number of circuits that can be covered on a single Minor Electrical Installation Works Certificate.
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G = standard disconnection time for a reduced low-voltage system in seconds.
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H = number of 'steps' to carry out continuity testing on a ring final circuit.
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I = number of live conductors supplying a standard three-phase distribution board.