Two quick questions...

[Andy Baker]

Good thread.

One of the main lessons learned over the years for team 45 has been wire length. In general, the bigger the wire is, the shorter it needs to be. For instance, we try to keep our wires on the battery and to the distribution panel very short. Also, we try to keep the wires to the motors as short as possible. There are a few reasons:

1. V=IR

As wire length increases, so does its resistance. Therefore, longer wires transmit less power. For instance, a 6 gauge wire has 0.00047ohms of resistance for every foot referenced here. During peak operating times, this wire may get 300 amps ran through it. If this wire is 3 foot long, then there is a 4% loss in voltage. If the wire is only 12 inches long, then the loss is 1%. This slight edge in power may give you the extra edge in a match.

2. Weight savings

Longer wires weigh more, as mentioned by mechanicalbrain.

3. Lower Center of gravity

If designers make the effort of keeping their wires short, then this usually leads to motors being closer to the base of the robot. Lower-placed motors means lower Cg. As we all know, low Cg is a beautiful thing. I'd rather have our robot not fall over.

As for labelling wires, that is good practice. Panduit has great products for this. Many professional electricians wire their labels with 1 and 2 letter codes. Some teams color code their labels also, for quick reference. If the labels are small and do not lead to question the safety of the wiring, a FIRST inspector should not make any team remove these labels.

Andy B.