Rule for finding out a phases color
- Thread starter Dexie123
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Yes the number divisible by 6 and the number before it is always the "C" phase. I always use the "C" phase as a reference and find the others in my head. For example on a BOY system take circuit #36, since it's divisible by 6 it's on the Yellow phase, so would be the number before 36, that would be #35 on the Yellow phase also. Some guys also use a system that incorporates the remainder of the division.
1) If the number is odd, add 1 to it.
2) Divide by 6.
3) The remainder will be either 0, 2 or 4.
If 0, the color is black or brown.
If 2, the color is red or orange.
If 4, the color is blue or yellow.
I prefer 4.
If single phase, divide by 4.
0 is black.
2 is red.
~Peter
2) Divide by 6.
3) The remainder will be either 0, 2 or 4.
If 0, the color is black or brown.
If 2, the color is red or orange.
If 4, the color is blue or yellow.
I prefer 4.
If single phase, divide by 4.
0 is black.
2 is red.
~Peter
Dave58er
Senior Member
- Location
- Dearborn, MI
Yes, you start with dividing by six. After that guys do it a few different ways. I like to think of it as subtracting multiples of six, that way I can get to numbers that are easier for me.
Your base is the given that circuits 1&2 are A phase, 3&4 are B phase, and 5&6 are C phase.
If you divide by 6 and have a remainder of 1 or 2 its A phase, 3 or 4 is B etc.
As infinity said evenly divisible by 6 will be C phase.
The way I do it is eliminate numbers divisible by six that are lower than the circuit number and start that as zero. This can make the math easier in your head.
An example would be a dimmer panel that has over a hundred circuits. If you needed a color for #137 its easy to figure 6 can go into 120 evenly so subtract it and start over. 137-120=17. That's just over twelve so subtract that and you have 5. 5 = C phase
Your base is the given that circuits 1&2 are A phase, 3&4 are B phase, and 5&6 are C phase.
If you divide by 6 and have a remainder of 1 or 2 its A phase, 3 or 4 is B etc.
As infinity said evenly divisible by 6 will be C phase.
The way I do it is eliminate numbers divisible by six that are lower than the circuit number and start that as zero. This can make the math easier in your head.
An example would be a dimmer panel that has over a hundred circuits. If you needed a color for #137 its easy to figure 6 can go into 120 evenly so subtract it and start over. 137-120=17. That's just over twelve so subtract that and you have 5. 5 = C phase
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