4 AWG Wires

Are 4awg clear red power wires allowed on the robot?

4AWG is perfectly fine, but I think you’ll need to clarify what you mean by “clear red”. Can we see a picture? I don’t think translucent insulation is banned, but it definitely needs to be identifiable as “red” (or another legal wire color for positive wires).

And the wire is tinned copper

Can you point me to a place where they might be banned?

That said, I’m not quite sure what you mean by “clear red”.

Longer answer:
You’ll need to pull up the 2021 Game Manual and turn to section 9.7: Power Distribution.
Rule R40, paraphrased: From the battery to the PDP, including the Main Breaker, needs to be a minimum of 6AWG.
–NOTE: 4 AWG is larger than 6 AWG, and is thus legal.
Rule R53, paraphrased: Refer to table for MINIMUM wire sizes based on circuit breaker amperages.
–NOTE: These are minimum sizes, and there’s no issue with using larger wires.

Here’s where you might run into trouble:

R56: All non-SIGNAL LEVEL wiring with a constant polarity (i.e., except for outputs of relay modules, motor controllers, or sensors) shall be color-coded along their entire length from the manufacturer as follows:
A. Red, yellow, white, brown, or black-with-stripe on the positive (e.g. +24VDC, +12VDC, +5VDC, etc.) connections
B. Black or blue for the common or negative side (-) of the connections.
Exceptions to this rule include:
C. Wires that are originally attached to legal devices and any extensions to these wires using the same color as the manufacturer.
D. Ethernet cable used in POE cables.

You’re not going to run into either of the exceptions, I don’t think. So what you’re really asking is, is “clear red” equivalent to “red”?

If https://www.amazon.com/Pyramid-RPR425-Gauge-Power-Clear/dp/B000K8IZCM is anything to go by, the answer is “probably yes but it will depend on your inspector”.

EDIT: Given the above picture, and past experience as an inspector, 99% legal without any hassle, 1% chance that an inspector gives you a hard time but is overruled by a LRI. I’d call it legal, it’s clearly red and clearly marked as 4AWG.

Edit #2: Though I would be cautious of weight (4AWG wire being heavy), and proper fits into the PDP if you’re using it on anything other than the battery-to-PDP wire routing.


Then are tinned copper wires ok too?tks

The specification is “copper wire”, both in R40 and in R53. I’m going to have to defer to someone else on whether “tinned copper” is allowable–I know that non-copper is banned (because it isn’t copper wire) but I don’t know about “copper with additives”. (Probably about 75% sure it’s OK, but that remaining 25% is going to be bugging me.)

@Al_Skierkiewicz, or any LRIs in the area, would y’all mind? Or would this be better in Q&A?

I believe if they mean plated copper wire, it should be fine. I don’t think FIRST HQ would be in support of this team having to strip the nickel plating with sulfuric acid.

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That may actually be CCA.

the coastal conservation association?

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Copper-clad aluminum, I assume.

OK, to answer the first question, yes, the clear red insulation does meet the rule. Tinned copper wire also meets the rule but may not be obvious to some inspectors who have no electrical background. Ask to have your LRI rule on it if there is a question. If the LRI does not have an answer, they will call me or Chuck for a ruling.
Copper clad or copper plated aluminum is not legal under the rules listed above.
As an additional note…
Clear insulation may not have the same temperature rating as other insulations. If the insulation on your robot shows any deterioration, you may be asked to replace it. Although it is not specified in the robot rules, insulation that deforms or becomes unstable under 100 degrees C is likely a poor choice for robot mains wiring. I most often see clear insulation in speaker cables.


To determine whether your wire is copper or copper-clad, look at the cross section/cut face of the wire. If you’re looking at copper, good to go. If you’re looking at something else (e.g. aluminum), don’t use it on an FRC robot unless you really like emergency re-wiring at competition.


You can also strip some and take a torch to it. CCA will burn away rather quickly.

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You have to be careful with this sometimes, as a cut face may appear all copper but it can be the cladding that has deformed to hide the rotten, aluminum core.

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It is partially dependent on the tool used to cut the cable. If it is really sharp, it is less likely to deform/smear the copper coating.

That was my first thought as well. It looks like some of the stuff that is pitched for car audio for folks that care about what it looks like rather than what it sounds like - most of that cheap stuff is Copper Clad Aluminum.

We use actual high strand count welding cable where the manufacturer doesn’t care about the looks - only the performance - sort of like we do :wink: No translucent cable jacketing in their product line…


True. I had some CCA wire that I could not be certain was CCA, no matter how close I looked at it. But when I took a torch to it, it was immediately clear that it was CCA.

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Copper-clad aluminum is great in applications that don’t see temperature extremes and are sensitive to weight. Its conductivity-to-weight ratio is better than pure copper. The copper cladding makes it (mostly; not strictly in critical applications) crimpable using ordinary lugs designed for copper, and it isn’t completely unsolderable with ordinary tools and materials (but crimps are usually better). In many ways it is actually perfect for FRC, except for the fact that it is not permitted. Its reputation probably comes from being corruptly substituted for copper at a given gauge, because its conductivity per cross-sectional area is lower than copper.

However, it is hard to find copper-clad aluminum wire with the same array of insulation options and certifications as copper wire, as these applications are esoteric.

This is in contrast to aluminum wire, which has issues related to the oxide layer interfering with connections. These have been adequately resolved in industrial practice (large-gauge aluminum wire is commonly used with special crimps and deoxidizing paste), but the procedures are unfamiliar in household use because many of the fittings are not rated for it.
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To settle if this cable is CCA or not: Looking closely at the picture, you can see it says “HI-OFC” on the side:

OFC stands for Oxygen-Free Copper and the HI appears to just mean “high-fidelity”. This wire appears to be legal.


I’d like to see the speakers that you would use 4AWG for! The opening scene from Back to the Future comes to mind…