Request a Re-Write of the Wire Color Rule for 2013.

Technical Electrical
1

From 2012

[R45]  All active circuit wiring with a constant polarity (i.e., except for outputs of relay modules, speed 
controllers, or sensor outputs) shall be color-coded as follows:
A.  Use red, white, brown, or black with stripe wire on the +24 Vdc, +12 Vdc and +5 Vdc connections. 
B.  Use black or blue wire for the common or negative side of the (-) connections.

I understand that there are many different wiring color codes in many different “application” realms.

i.e.
house wiring black is hot, white is neutral,
Automotive, Red is +12v and Black is Negative, Ground, +0V
Industrial controls, Red is AC voltage, Blue is DC voltage, white is common ac, white with blue tracer is common dc.
DC industrial sensors, brown +24v, blue 0v, black signal…

Last year the team mixed the +24v and the +12v in the wiring as both were red. So this year we are building a 1114 Kitbot on steroids, and I brought in some blue mtw, and some blue/wht mtw to wire the 24v circuits with. Of course I was questioned to the rule, by one of the students, (who thought them to read the rules when wiring?) and found Blue was reserved for negative… which was not the way I was asking them to wire the bot.

So now that I have read the rule, it seems to me that it could use a little work. Based on the rule, I think I can wire the whole bot with everything black, and be legal? I guess I would be ok with that, if the rule also said something about wire labels and clearly identifying conductors in the circuit.

So just some food for thought on this rule, and what wiring practices we are trying to dictate to be followed on the bot.

I would suggest that the rule not give specific colors that can be used, but say that the Positive and Negative colors be different and consistant across the bot. I would also like to see that +24 & +12 be different colors in practice.

(When you see battery voltage readout on the drivers station at 17, you’ll know why. . . )

Comments, Discussion Welcome.

2

Based on the rule, I think I can wire the whole bot with everything black, and be legal?

The positive lists “black with stripe” so solid black for both wouldn’t be sufficient.

I think the color lists exist mainly to help inspectors so that they don’t have to keep a mental list of what color is what path on every team’s robot. It also helps when other teams provide assistance to you! :slight_smile:

3

It also makes it somewhat cheaper to buy wire, as a team would not have to buy a dozen different colors of different gauges.

4

The current rules do allow use of different colors for +24 and +12V. For example, you could use red for +12V and brown for +24V.

Also, we have been allowed to use stripes on any wire (other than DC Return), as long as the main color meets the rules. DC Return wires are strictly black.

If you’re seriously requesting a change to the rules, Chief Delphi isn’t the proper channel. You’ll need to contact the Game Design Committee.

5

A team wouldn’t have to. You could still buy a bunch of red and black if you wanted.

I also think this rule as written in 2012 doesn’t make a ton of sense either, especially for sensor power wires. When wiring multiple sensors in the same location, I’ve often seen muli-conductor wire bundles used, which likely only have one red and black (if at all), while multiple sensor supplies and grounds are used (possibly independent analog/digital supplies, or something else).

6

The rule, as it stood last year, gives you plenty of options - 4 for the positive terminal, 2 for the negative terminal.

I certainly applaud your efforts to separate your wire colors for 12/24V… just do it within the confines of the rule :slight_smile: There’s nothing wrong with using red and black for 12V, and white and blue for 24V, for example. It’s within the rules, and it gives you the separation you want. For my team, we haven’t used pneumatics since our first year. As a result, we’ve standardized our wire colors around gauges, so it’s obvious what gauge the wire is at a glance.

This rule hasn’t changed for a very long time, and I doubt you’ll see it change much in the future. As you pointed out, industry applications have their standards and codes, why shouldn’t FIRST have its standards as well? As an inspector, I can tell you that having standardized wire colors makes things MUCH easier when helping out any team at the competition. It allows us to unplug things, swap components, etc without worrying about what that particular team’s “standard” is - we follow the FIRST standard and everything works out fine.

7

How do you do that?

I thought the following Q/A response last year was interesting:

FRC3335 on 2012-01-20 | 4 Followers
Q201 Q. With respect to R45, would it be acceptable to use black wire for the +24, +12 or +5 Vdc connections that: 1) is wrapped over it’s whole length with red, white or brown electrical tape 2) is wrapped with red, white or brown electrical tape at each end 3) has a white stripe painted along it’s length
A. No.

It’s not even permissible to change the color of a wire.

8

A multi-conductor cable is typically going to include all the colors listed as being acceptable for supply and return colors (assuming a typical conductor count). There also will be a few other colors that can be used for sensor values.

As an inspector, I both love and hate this rule. I really like being able to go up to any robot at a competition and make at least some sense of the wiring. This is very important, as I often have my head inside robots that are not working. I absolutely hate having to tell teams that did not bother to read the rules that all the pretty wiring on their robot is not in compliance with said rules and needs to be fixed.

I understand the reason the rule is written the way that it is. Would love to have them add some more colors, like yellow and orange, etc. My team was frustrated last year by not being able to use multi-color ribbon cable for a run to multiple pneumatic solenoids on the end of the manipulator arm. But it did not meet the color requirement so they worked out another way to do it.

Could be worse, I worked on a project once where the specification was “All wire shall be green”. It was a translation error, should have been “all ground wire shall be green” but no one wanted to fix it, so we had 50 pin connectors with all green wire on them. I don’t recommend that :slight_smile:

9

I’ve seen harnesses where all of the wire except the main battery cable to the fuse panel is 18 or 22 gauge white, labeled at each end with paper and clear heat shrink. The harness had very few issues, especially for how it was treated.

I’ve always interpreted the rule such that any load-side connections between a relay or victor can be any color. We had a specific instance where we used multicolored 14 gauge automotive wire between the Victors and the motors mounted on our turret, to reduce weight over the 12 gauge red/black zip cord we usually use. The weight savings were significant enough for us to do it during the 6 hour unbag window between two competitions.

Maybe the rule should be re-written to exempt low voltage sensor wiring (6v or lower) and all switched circuits. As it is now, Jeff’s situation would have been legal (IMO) by the letter of the rules if you had used a spike relay to control the pneumatics instead of the pneumatics bumper (as long as the ground was black or blue) which makes very little sense.

10

I am seriously requesting discussion, Al will eventually see this, and see if it has any merit. I am only 2 years into FIRST, so asking for some understanding.

I guess that is my point, if you want standardization, then pick A color and stick with it.

I don’t understand the points about inspection, as if you really had a standard, all of the robots would follow the same color code. It would even be more understood.

I was not going for this strict standard in original post, but now as I look at the colors, and the comments, I really have an issue with white being used as a positive. In the US and most other nations, white is not used as a positive. We wired the bot with the white with blue tracer on the positive, and blue on the negative to meet the spec. The issue I have with that, and the reason for the post, was it is completely wrong, to what these kids will find in a couple of years after FIRST.

I am glad that Andrew posted, but as a student that came up through the FIRST program, now goes to Kettering, and works at Chrysler. There is not a single application he will come across, where white will be a positive.

NEC says so. (66.9 robot control falls under this spec, but obviously, I wouldn’t make the case that an FRC robot is a control panel, and Andrew might, as it appears that anything mobile doesn’t fall under any standards.)

That just seems wrong, to me.
I think it is a disservice.

For the humor…
For the record the kids didn’t mind, and the electrons still flowed unknowingly.

11

The rule has exemptions already for :

outputs of relay modules, speed
controllers, or sensor outputs

The rule also pertains to constant polarity wires only.

The spike relay still needs to be wired (for power) and then it uses a PWM cable for control Using the pneumatics bumper eliminates the need to power the spike through the power distribution panel.

12

If you’re only using one or two solenoids, it is likely weight negative to do all of that instead of using the pneumatics bumper and NI high side switching module (which is not light at all), since you must already wire the pneumatics bumper for power. However, even if you had more solenoids, you could still do that and use incorrectly-colored wire for the high sides to the pneumatic solenoids, which you cannot do when using the pneumatics bumper.

I think all sensor wires should be exempt, including sensor power and sensor grounds.

13

I agree with you about sensor wires or wires carrying some arbitrary low amount of current whatever that might be. It would be so much easier to use ribbon cables for those control functions…

One of the issues is that many of us have 24 volt solenoids and they cannot be controlled via the spikes…It is harder to find 12 volt solenoids in commercial applications for some reason… We always have two pneumatic shifters (controlled via one solenoid) so it is a tradeoff for us… but we usually use 2-3 more pneumatics along with the shifter…

14

I believe FIRST was responding to non-North-American teams which were having trouble finding wire that did not comply with IEC 60445 (which is described in rough terms here).

Incidentally, this thread has prompted me to go track that standard down for another project, so if I find a copy at the library, I’ll verify whether FIRST’s rule is consistent with it. (If I read that linked chart correctly, our systems are unearthed DC, not negative-earthed DC, so grey, not blue should be reserved for negative. But I’d rather double-check the definitions before making any conclusion.)

I wouldn’t say this is at the top of my list of rules that need to be taken out back and shot,1 but it has issues like no exemption for custom circuits (even COTS ones like fans), and odd consequences like when someone combines +12 V and +5 V to get a +7 V output with an unusual voltage reference (they’re both red wires).

1 Bumpers.

15

Scott et al,
The color codes (and ampacity specs) are taken from the NEC (National Electrical Code) and the European equivalent of the NEC. In past years the rule had stated the color codes were for PD branch circuits so that sensor wiring was excluded.

16

The standards are some what conflicting.

IEC likes Blue for zero volts. The NEC likes blue for non zero DC volts. A good many panels in the US will use Blue for +DC & Gray or Blue with white stripe for 0V. The AC parts of the NEC call for white for neutral or grounded conductors & Black for non grounded AC conductors (Highly simplified). In DC Black for zero volts & Red for positive is pretty universal. Except Black & White twisted pair is really common for shielded control wires. Some plants like using black for the 0 V which makes white positive. Others use white for O V (It is the “neutral” color) which makes black positive (hot). The DC 0 V often gets grounded somewhere in the plant, making the black wire the grounded conductor. (A big NO if you are on the AC side of building wiring.) The take away here is unless you are somewhere that is really rigid about following one standard: you need pay attention to where the wire is going in addition to the color of the wire.

I would like to see the rule for wiring colors relaxed for multi conductor cable going to sensors & other low power items. The 2012 rule still requires the sensor supply wires conform to the color code. I can see still requiring the color code to be followed on single conductor wire.

17

There really is no good existing standard for FIRST to copy. The NEC, UL 508, NFPA 79 all are mostly AC centered. With the NEC we can basically use anything but gray, green and white for our ungrounded “hot” AC conductors.

For FIRST I’d like to see something like red for +12, blue for +24, and yellow (or similar) for +5, and black for all negative conductors. Conductors in cables should be allowed to be re identified if you want. If you want to identify negatives per voltage twisting, tyrapping, lacing, labeling, taping (either “phase” taping the negatives or using tape to bundle) would be optional.

No matter what the color code is though everyone should get into the habit of using a meter to confirm. One of the first thing you learn in the real world is once maintenance guys get at it and contractors guys start applying WIT (What’s In the Truck) all bets on color are off. :ahh: