Skill room

Calculations Room

Calculations fail more candidates than any other section. On the Texas TDLR exam the Calculations part is now scored on its own, and the most recent published pass rate on it was 20.56 percent. The fix is not more formulas. It is a repeatable setup so a three-step problem never freezes you. Drill one type at a time.

Last reviewed June 2026 · Staff Answer

Daily drill · original

A 120-volt branch circuit runs 70 feet one way on 12 AWG copper carrying 16 amps.

What is the approximate voltage drop? (K = 12.9, 12 AWG = 6530 cmils)

Pick an answer to see the work and why each wrong choice traps people.

What this room is for

  • Learning a clean setup that works on every calculation type
  • Working one calc type at a time until it is automatic
  • Talking through where a number came from when you get stuck

What not to post

  • Asking for the answer without the steps. The steps are the skill.
  • Posting copied exam questions. Original scenarios only.
  • Sharing personal details. Keep it about the math.

Answered questions in this room

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