The Continuous Load 125% Rule Explained for Electricians

What counts as continuous

A continuous load is one where the maximum current is expected to flow for three hours or more. The NEC defines it, and the definition is in Article 100 of your book. Lighting in a store that runs all day is continuous. A motor that starts and stops for short cycles is not. When a question describes a load, ask first whether it runs three hours or more. If the stem says so, or says the load is continuous, apply the rule. If the stem does not say, do not assume it.

Where the rule lives

The branch circuit rules are in 210.19(A)(1) for the conductor and 210.20(A) for the overcurrent device. Feeders have matching rules in 215.2(A)(1) and 215.3. Standard ratings you round up to are listed in 240.6(A). We cite by number only, so open your 2026 NEC and confirm each paragraph letter, since numbering can shift between editions. The key point is that the rule affects the minimum size of the conductor and of the device, but you read it as an addition to noncontinuous load, not a multiplier on everything.

The method in four steps

1. Separate the load into continuous and noncontinuous parts.
2. Multiply the continuous part by 1.25.
3. Add the noncontinuous part. The total is the minimum the conductor and device must handle.
4. If the question asks for a device rating, round up to the next standard size in 240.6(A). If it asks for the calculated load, stop at step 3.

Worked example

A branch circuit serves 18 A of continuous lighting and 7 A of noncontinuous receptacle load. The calculated minimum is 18 × 1.25 = 22.5 A, plus 7 A, which is 29.5 A. If the question asks for the minimum overcurrent device rating, 240.6(A) lists the next standard size above 29.5 A, and you read it from your book. We do not quote the list here because the value belongs to your copy of the code.

Now run the conductor side with the ampacity steps in our conductor ampacity guide. The adjusted ampacity of the conductor must be at least 29.5 A at the terminal temperature column that applies. The continuous load rule raises the required number, and correction and adjustment factors lower the available number. Put them on opposite sides of the comparison and you will not mix them up.

The three common mistakes

Applying 125% to the whole load. Only the continuous part is multiplied. If you multiply 25 A of total load, you overstate the minimum and may pick a device that is too large.

Rounding too early. Do the multiplication and addition with full numbers, then round to a standard device once, at the end.

Applying the factor on both sides. Some candidates raise the load by 125% and also lower the conductor by a safety margin of their own. The comparison is the calculated load against the corrected ampacity. Nothing else belongs there.

A question you should always ask

"Does the exam say copper?" The bulletin tells candidates that unless a question says otherwise, all conductors are copper. It also says not to consider code exceptions or optional calculation methods unless the question directs you to. The same goes for any exception to the continuous load rule: leave it alone unless the question points you to it.

Check your speed

This is a two-minute problem if you have done it twenty times. Make a set of ten loads, each with a different split of continuous and noncontinuous current, and time yourself. When you have the steps down, run the result through the voltage drop calculator to see whether the run length changes your conductor choice.

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FAQ

What is a continuous load?

A load where the maximum current is expected to continue for three hours or more. The definition is in Article 100.

Do I multiply the whole circuit by 125%?

No. Multiply only the continuous part, then add the noncontinuous part.

Is the 125% rule for the conductor or the breaker?

Both. The conductor rule and the device rule are in separate sections, 210.19(A)(1) and 210.20(A) for branch circuits.