breaker rules

[Joe Ross]

In the past, FIRST has been very clear about what size breakers to use with each kit component. This year the rules specify that the robot controller, compressor, and spikes must have a 20 amp breaker. The only rule about motors (that I can find), is that speed controllers may have a 20 amp, 30 amp, or 40 amp breaker, <R83>.

The guidelines document does suggest that the CIMs and Fischer price use 40 amp breakers, but even then doesn't make it a rule.

Did FIRST forget a rule about circuit breakers and motors, or is the only rule this year that the wire size must match the breaker size?

[Greg Needel]

hey Joe,

last year there were no set rules either for the drills and the chips and you could choose which breaker you used, mainly because of the separate fuse block for the 40 amp fuses but i assume you can use which ever you want with the caution that if your robot trips it is your own fault.

maybe we will see more of a spec when the inspection sheet comes out

[Al Skierkiewicz]

This is one area that rookies will be behind the curve since the rules are a little misleading. The breaker size is set by rules so that the wire size is protected by the breaker rating. i.e. a 30 amp breaker should trip before the #14 wire it protects would melt.
Competitive teams will use the 40 amp circuit breakers and #10 wiring for the Chalupas and FP motors. I did see a few teams that used the 30 amp breakers on the big motors and wondered why. It could have been a weight saving idea but I didn't really see a need for that reduction in available power.

[BrianBSL]

I am glad FIRST changed it to this, although I wish they would have made it clearer in the rules. Certinally the globe motor doesn't need 10 gauge wire running to it, as previous years had required.

[Andy A.]

Originally Posted by Al Skierkiewicz

I did see a few teams that used the 30 amp breakers on the big motors and wondered why. It could have been a weight saving idea but I didn't really see a need for that reduction in available power.

Al-

I think the use of 30 amp breakers where 40 amps could have been used was often do to the knowledge that the motors may repeatedly stall, and a lower rated breaker might save the motor faster.

-Andy A.