wiring color question

Hey guys,

One concern we have for competitions is our wiring. We used color coded wiring so we could follow wires easily, for example CIM1 uses blue and yellow wires, CIM2 uses purple and red wires. This made wiring very easy this year. We also used red heat shrink for positive and black heat shrink for negative, but only over the last two inches of the wire to cover the connectors. Hence, you can tell that the wire is positive or negative, AND you can trace the wire across the chassis. There is a rule that says your wires should be red for positive and black for negative, I forgot which rule number it was. Now, do the wires have to COMPLETELY be red or black? And will our funky color coded wires pass inspection?

Thanks.

while i like this idea if you personally can tell which is which, i don’t think the rules are very forgiving:

5.3.9
<R81> All wires distributing power with a constant polarity (i.e., except for Relay Module, Speed Controller, or
sensor outputs) must be color-coded as follows:
• Use Red, White, or Brown wire for +12 Vdc and +5 Vdc connections.
• Use Black or Blue wire for Common (-) connections.

<R81>:

All wires distributing power with a constant polarity (i.e., except for Relay Module, Speed Controller, or sensor outputs) must be color-coded as follows:

  • Use Red, White, or Brown wire for +12 Vdc and +5 Vdc connections.
  • Use Black or Blue wire for Common (-) connections.

The rule says “must”, not “should”. However, it’s not explicit about about the entire wire being of the specified color, so maybe your heat shrink at the ends will count as making it “color-coded”. I don’t know how flexible inspectors will be about it.

Note also that it says “except for … Speed Controller … outputs”. If you just used the color-coding scheme on the run from the Victors (or Spikes) to the motors, you should be just fine.

Thanks for all your input.

Just one question: As Eldarion brought up, this excludes victors and spikes and sensors. So, if the only color coded wires are the ones from the victors/spikes to the motors, we should be fine? We still have red/black wires giving power to the victors/spikes.

Thanks everyone.

yes, if your rainbow wires are on the output side of the Victors and Spikes you are ok.

There is no polarity issue there- if you wire a motor backwards it will happily run backwards - it wont burn up like a Victor would with reversed power.

Veselin,
As an inspector I would really need to see the robot before I would pass on this. On the surface it seems to satisfy the rules but the inspector is there to make sure that the robot is safe to compete and easy for field volunteers to help you run in case of problems. I wouldn’t expect an automatic pass on this at any or all competitions you attend. (what passes at one event may not pass at another) I always recommend color coding wires, and we use color coding tape on everything including PWM cables, speed controllers, wires, motors and circuit breakers.

I can’t tell you about this year, but last year my team wired everything in green and white wire, in no particular pattern. However, we did wrap the ends of the negative wires in a bunch of electrical tape, so you could tell it was negative. The inspectors said it was fine (I made sure to ask just in case) and we went about our business.

For some of the power wiring, what we did was take the black and red wires, chuck them into a drill and twist them together (not too tightly as to compromise the insulation). This makes for a neat cable that can be traced across the chassis without much of a problem.
Taking this one step further you could twist onto the red/blk bundle a third ‘tracer’ wire of a different color (and maybe lighter gauge) to identify that particular pair.

We followed Al’s advise this year and it has been a great help in troubleshooting a problem.

John,
This isn’t a bad idea. Teams should be cautioned to not wind the wire so tightly that it stretches (reduces the cross sectional diameter and current handling ability) or squeezes the the insulation such that the wires will become shorted.