Electrician Apprentice HQ #1 Online Resource For Becoming An Electrician 
Last updated on October 22nd, 2026.
You can identify circuit number colors in a 3 phase panel using the Rule of Six.
The method uses division to find the color.
Divide the circuit number by six to work out which wire color to use.
You can use the calculation without a color coded wiring chart.
How To Identify Circuit Number Colors in a 3 Phase Panel
This method of dividing a circuit number is sometimes easier than carrying around a electrical wiring color code chart. Usually I make up temporary panel schedule on piece of notebook paper before I start pulling in new wires.
Colored tape on circuit breakers helps identify wiring colors. Learning the mental calculation is another useful skill for a skilled apprentice.
A 3 phase panel wiring is A, B, C – left to right- and top to bottom. Circuits are labeled with the odds on the left and the evens on the right.
Normal Wiring for a 120 / 208 V 3 Phase Panel
When using the rule of six you will reference the first six circuits, their phase and color.
Use the result as follows:
If a number divides evenly by 6 then that circuit will be the same phase color as the number 6. If there’s a remainder, use that to determine the wire color.
Example 1:
What color is circuit #24? Divide the number 24 by 6. The answer is 4. Since 6 divided evenly, circuit #24 will be the same color as circuit #6. Using the panel or layout above find what color circuit 6 is. Circuit 6 is BLUE, which means circuit number 24 is BLUE.
Example 2:
What color is circuit #11? Divide the number 11 by 6. The answer is 1 with a remainder of 5. Use the remainder of 5 as your reference and find what color circuit 5 is. Circuit 5 is BLUE, which means circuit 11 is BLUE.
Example 3:
What color is circuit #20? Divide the number 20 by 6. The answer is 3 with a remainder of 2. Use the remainder of 2 as your reference and find what color circuit 2 is. Circuit 2 is BLACK, which means circuit #20 is BLACK.
Focus on memorizing the colors of the first six circuits in a panel. Use BLACK, RED, BLUE for circuits 1, 3, 5 and 2, 4, 6, respectively.
This method applies to various voltage color schemes you’ll encounter. For instance, a 277 / 480 volt panel typically uses BROWN, ORANGE, YELLOW for circuits 1, 3, 5, and 2, 4, 6.
If you’re having trouble, try remembering this rhyme – “If it’s divisible by 6 it’s blue, and the one before it too.” This rhyme only work on 3 phase 120/208 volt panels, but you could substitute yellow if you’re working on a 277/480 volt panel.
Leave a comment if you have questions or an experience that could help another apprentice.
