Circuit Colour ID

Identify phase colour by circuit number using the Rule of 6. Enter a circuit number to get the correct phase colour for panel wiring.

How circuit colour is identified

In a three-phase panel, phases repeat in a fixed pattern as you move down the circuit numbers. The Rule of 6 uses the circuit number to tell you which phase a breaker lands on, because breaker positions alternate phase every pair of numbers.

Odd circuit numbers run down the left side and even numbers down the right, and each phase covers a predictable block of numbers. Enter a circuit number and the calculator returns the phase and its standard identifying colour for your system.

Worked example

On a standard panel, circuits 1 and 3 are phase A, circuits 5 and 7 are phase B, circuits 9 and 11 are phase C, and the pattern repeats. So circuit 15 lands on phase A again. The calculator maps that phase to the colour convention you select.

Code reference

Conductor colour coding is set by CEC Rule 4-036 and related identification rules, and by NEC Article 210.5 and 215.12 for branch and feeder identification. Exact colours depend on the system voltage and local convention. The phase sequence itself follows the panelboard layout, not a numeric code table. Confirm colours with your jurisdiction.

Common mistakes

Frequently asked questions

What is the Rule of 6 for panel circuits?

The Rule of 6 uses the circuit number to identify which phase a breaker connects to, since phases repeat in a fixed pattern down the panel. It lets you find the phase without tracing the busbar.

How are odd and even circuits arranged in a panel?

Odd circuit numbers run down the left side of the panel and even numbers down the right, with each phase occupying a predictable block as you move down.

Are phase colours the same for every system?

No. Colour conventions differ by system: 120/208 V, high-leg delta, and 347/600 V each use different identifying colours. Always confirm the convention for your jurisdiction.

What colour is phase B?

It depends on the system. On a common 120/208 V convention phase B is often red, but 347/600 V and delta systems differ. Select your system in the calculator for the correct colour.