Quick Hits

EPISODE 11 — 265.19(A)

Minimum Conductor Ampacity

SLIDE 1 — 265.19

CONDUCTORS — MINIMUM AMPACITY & SIZE

Now we get into conductor sizing.

265.19 sends us to applicable ampacity requirements and then establishes branch-circuit sizing requirements.

The general rule:

Branch-circuit conductor ampacity ≥ 125% of the designed potential load of utilization equipment operating simultaneously.

SLIDE 2 — THE 125% RULE

Here's the exam formula:

DESIGNED POTENTIAL LOAD

× 125%

= MINIMUM CONDUCTOR AMPACITY

Example:

A designed simultaneous load is:

80A

80A × 1.25 =

100A minimum conductor ampacity

SLIDE 3 — DON'T CONFUSE THE NUMBERS

Notice the wording.

265.19(A) is talking about:

CONDUCTOR AMPACITY

Not simply the branch-circuit OCPD rating.

Always identify what the question is actually asking you to calculate.

SLIDE 4 — REVIEW ⚡

A branch circuit has a designed potential simultaneous load of 80A.

What minimum conductor ampacity does 265.19(A) require under the general rule?

A. 80A

B. 90A

C. 100A

D. 125A

ANSWER: C

80A × 125% = 100A

⚡ FOLLOW FOR MORE DAILY QUICK HIT STUDY NOTES

← View Chapter 2 Home

← Back To Article 250 Home

← Back To Quick Hits Home