Flat 12AWG Wire Legal?
 

For various reasons I am looking into using flat 12AWG wire to drive the two motors for our shooting mechanism. I have found no rules thus far that prohibit the use of flat wire, as long as they are the appropriate gauge for the application [R44]. Additionally, the lack of color coding on the flat wire is not an issue as pointed out in [R45] because the output from the Jaguar is not necessarily constant polarity (granted we'd still mark the wires for reference).

Here's the wire I'm looking at: http://cableorganizer.com/flatwire/audio-cable.html (P/N FTW-55921201)

Is there anything I've missed that prohibits the use of flat wire? Thanks

Re: Flat 12AWG Wire Legal?
 

I don't think it is, the problem is the fact it is not color coded. even if there is no set polarity I would still be wary. you are right the rules don't prohibit the use but in past competitions inspectors vary so one might pass you and later you might get dinged. So I guess it is legal but I would still check with the GDC for an official ruling

Re: Flat 12AWG Wire Legal?
 

Either way this stuff is very cool.

Re: Flat 12AWG Wire Legal?
 

Assuming it is legal, a couple of other concerns should be noted:

1) At $2 to $3 a foot, this stuff is quite expensive.

2) If you have problems with it at competition such as open or intermittent connections, how are you going to troubleshoot it?

Re: Flat 12AWG Wire Legal?
 

I'd agree that the stuff is cool, and I can relate as to the uses on a competition robot, but we have had experiences where we used 18AGW wire that was white and yellow, and got rejected by an inspector. Not a huge issue, we just swapped out for red and black at the competition. If you can avoid it, I'd suggest you do simply to avoid complications in the future.

Re: Flat 12AWG Wire Legal?
 

Yellow wire is illegal per [R45].

The lack of color coding is an issue because color coding is required as per the connection it's used for, not the polarity of the power flow.

Re: Flat 12AWG Wire Legal?
 

Do you have a rule to support this? Wire that can change polarity is expressly exempt from R45.

Re: Flat 12AWG Wire Legal?
 

True, but [R45] also says;
I think that little bit rules everything else out. Having been an inspector last year, we were instructed to make sure everything was color coded in a consistent manner, and we checked the path of most major wiring (speed controllers and such)

Re: Flat 12AWG Wire Legal?
 

R-45 requires color coding only on the power side of the speed controller or relay module. On the motor side of the controller, you may use whatever colors you want since power is passing in both directions. Past the controller there is no consistent + or - to deal with. Both students and inspectors often get confused about this.

Dr. Bob

Chairman's Award is not about building the robot. Every team builds a robot.

Re: Flat 12AWG Wire Legal?
 

I'm well aware of that fact sir. I miss read the OP, my bad.

Re: Flat 12AWG Wire Legal?
 

How do you intend to connect this stuff to the speed controller and the motor?

Re: Flat 12AWG Wire Legal?
 

I think it's possible so scrape off the insulation and solder on a short length of standard 12AWG wire on each end for connections. In any case, it is unlikely that we'll be using this stuff as plans changed shortly after I posted this thread. Still a useful discussion, though, for sure.

Re: Flat 12AWG Wire Legal?
 

Sorry I didn't see this post earlier. There is nothing illegal with this wire being used on the robot. While it is not color coded and can be used on the output of controllers, there must be some marking on it indicating polarity. I am often cautious of using "audio" wire as many companies over state specifications. What may be termed #12 may in fact merely act similar to #12 in this application. Robot wire specifications are taken from the NEC handbook for open (not in conduit or confined spaces) wiring. Another thing I would consider when looking at this wire is it's survivability on a moving robot. Bends over structural metals could breakthrough the outer cover exposing the conductive material inside.

Re: Flat 12AWG Wire Legal?
 

I believe you can't even cost it by the foot unless you can BUY it by the foot. The shortest spool is 25' @ $75. You would have to cost it at $75 even if you only used 6".

- Bryce

Re: Flat 12AWG Wire Legal?
 

Per unit cost (per foot, per lb, per inch) is a standard cost comparison tool. Instead of saying, let's say, 25'/$75 for flat versus (making up numbers here) 100'/$50 for normal, you can just say that it's $3/foot versus $0.50/foot.

By the rules, yes, you're correct (though many places will cut bulk items for you and sell at a per-foot rate). But what you missed was the implicit cost comparison to normal wire.

Re: Flat 12AWG Wire Legal?
 

Bryce,
I would check the BOM costing descriptions again. Think of buying a 4x8 sheet of plywood but only using 2x2 on your robot.

Re: Flat 12AWG Wire Legal?
 

Al, if 4x8 is the smallest available size of that plywood, the entire 4x8 sheet has be accounted for in the cost accounting. That's how I read [R16]'s blue box, last example.

Re: Flat 12AWG Wire Legal?
 

R16
Example: A team purchases a 4 by 4 ft sheet of aluminum, but only uses a piece 10 by
10 in. on their Robot. The team identifies a source that sells aluminum sheet in 1 by 1 ft
pieces. The team may cost their part on the basis of a 1 by 1 ft piece, even though they
cut the piece from a larger bulk purchase. They do not have to account for the entire 4
by 4 ft bulk purchase item.

There are local A/V and home theater shops that do sell these materials by the foot. Some research is necessary.

In that case you'd be fine. But if you can't find a supplier for purchasing by the foot (for the exact part) you can't do this.

- Bryce

Re: Flat 12AWG Wire Legal?
 

http://www.pacificcable.com/Picture_...me=PCC-12-2-50 This site has a simmilar #12 wire listed as only being rated to 20A, FIRST, and NEC rate 12 gauge wire at 40 amps (41 for NEC). I would want a better understanding about where this 20A rating comes from before using it on a robot. The Flatwire brand site seems to imply that its product doesn't comply with NEC standards as they mention a new line that does comply to be used for power distribution.

Re: Flat 12AWG Wire Legal?
 

James,
Wire specs for NEC are determined by temperature rise for the insulation and by voltage drop at specified current over a specified length. In the case of the flat wire, certain signals have a hard time propagating down flat wire. For audio (and other AC currents), the shunt capacitance also becomes a factor as the max 80' length spec alludes. The 20 amp spec is likely because this product is intended to be painted over. At more than 20 amps continuous, the paint would likely start to bubble.
As for NEC current specs, the test on a single wire size is how much current can the wire transmit before the voltage drop at the end of a standard length exceeds a certain percentage. The current/voltage standards used for aircraft instruments is also used and more stringent.