Apprentice path · Stage 13: Conductors and markings · Lesson 42

AWG: smaller number, larger wire

On the AWG scale the numbers run backwards: the smaller the gauge number, the bigger the conductor.

Why this matters on the job

It is counter-intuitive, it comes up constantly, and getting it backwards means reaching for a conductor smaller than the one you meant.

How to think about it

  1. Within the AWG scale, lower numbers mean larger conductors.
  2. A larger cross-sectional area generally lowers resistance.
  3. Remember that ampacity also depends on installation conditions, not just size.

Worked through

Line up 14, 12 and 10 AWG and they get physically bigger as the number gets smaller. More copper in the cross-section generally means less resistance per unit length, which is the same idea as the voltage-drop lesson seen from the other side. What it does not mean is that you can read a conductor size and know its ampacity: the installation conditions are part of that answer too.

Check yourself: Which is the larger conductor, 10 AWG or 12 AWG?

Answer: 10 AWG is larger than 12 AWG.

The AWG scale runs backwards -- the lower number is the bigger conductor. So 10 is larger than 12, and 12 is larger than 14.

Watch out for: Going from conductor size straight to a breaker. Size alone does not select a breaker, and ampacity depends on installation conditions as well as on the conductor.
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Written from the owner's poster for this lesson. Nothing added beyond what the poster states.

Written for Texas apprentices as free study material. The Texas apprentice licence is an application, not an exam (Occupations Code 1305.161), and nothing here counts as apprenticeship hours or continuing-education credit. VoltMark is not affiliated with, endorsed by, or sponsored by NFPA, PSI, TDLR, or any state or local licensing authority. Always follow your employer's safety programme and your supervising electrician.