Multiple SPIKES wired to same fuse

[7-11number1]

Does every spike need it's own 20A Fuse (upstream) or can multiple SPIKES be wired to one 20A fuse if the current draw on M+ and M- is low e.g (powering solenoids on pneumatic vales)?

[d235j]

According to the RULES, every SPIKE needs its own 20A breaker (in addition to the fuse right on it).

[EricH]

Originally Posted by d235j

According to the RULES, every SPIKE needs its own 20A breaker (in addition to the fuse right on it).

I can't find this specifically in the rules, but it seems implied by <R55>. Maybe you can show me the rule you are thinking of, because I can't find it. You are right about the 20A breaker, although, on the compressor at least, you don't need the fuse along with the breaker.

[Al Skierkiewicz]

<R55> All active circuit breaker / power distribution panel branch circuits shall be protected from
overload with an appropriate value auto resetting Snap Action circuit breaker from the Kit Of
Parts....
 Relay modules must be protected with a 20A circuit breaker.

Followed by...
<R56> Each power regulating device (Victor speed controller or Spike relay) shall control one and
only one electrical load (motor, actuator or compressor). Multiple low-load devices (e.g.
pneumatic valves) may be connected to relay modules (but only one motor may be
connected to each relay module).

The electrical principle is simple, based on total Spike failure. Each Spike is fed with a #18 wire and each #18 wire must be protected with a 20 amp circuit breaker.

[Dad1279]

I'm not sure I am in agreement. I interpret this differently. Perhaps this is a question for the First Q&A.

<R55>
.....
• Relay modules must be protected with a 20A circuit breaker.
.....

Relay Modules is plural (more than 1) with a single breaker.

[Rosiebotboss]

Originally Posted by Dad1279

I'm not sure I am in agreement. I interpret this differently. Perhaps this is a question for the First Q&A.

<R55>
.....
• Relay modules must be protected with a 20A circuit breaker.
.....

Relay Modules is plural (more than 1) with a single breaker.

Go ahead and ask FIRST Q & A if you'd like. But, my money is on Al's interpretation.

[Daniel Bathgate]

Ask the Q&A, and if you are allowed to wire them together, print the answer and bring it to the competition. Without a direct answer from the GDC, you are likely to get grief from the robot inspectors no matter how the rule is intended. I know last year our chaining of all of the negatives from spikes controlling solenoids didn't fly with the inspectors.

[Russ Beavis]

As the Chief Inspector for FIRST, I STRONGLY encourage that someone address this via Q&A. I could give you my interpretation and whether I would allow multiple Spikes on the same breaker but my preference is to make this "official" by using the Q&A.

Also, I didn't sense any interpretations in Al's response. I don't think that he explicitly stated whether he would allow or disallow multiple Spikes per breaker. He did, however, state something very important - trying to actuate a pair of 20A Spikes simultaneously on a single 20A breaker (as an example) is asking for "failure" (ie an open breaker) and should be avoided based on solid engineering principles. IF multiple Spikes per breaker are allowed, 18AWG wire must certainly be used everywhere (per rule <R47> with a single exemption for pneumatic valves).

Russ

[Dad1279]

Asked.

To add to the confusion, I am also named Al. So Rosiebotboss is correct either way....

[The Lucas]

Originally Posted by Daniel Bathgate

I know last year our chaining of all of the negatives from spikes controlling solenoids didn't fly with the inspectors.

Originally Posted by Dad1279

Asked.

To add to the confusion, I am also named Al. So Rosiebotboss is correct either way....

Did your question include daisy chaining the grounds to spikes? I would also like to see that clarified.

[Al Skierkiewicz]

So as to allay confusion, I am Al, AKA Big Al, Al S, Mr. S or Mr. Skierkiewicz depending on the age of the person who is addressing me, what First program you are in and the length of time we have competed with each other. Certain others have used other unauthorized names when addressing me, Dana included. We won't go there, thank you very much.
As to the Spike vs. Breaker controversy, we have been warned in the past about "lawyering the rules". As a broadcaster, single points of failure are to be avoided at all costs. As an example, if the same breaker were used on on two Spikes, one to ingest the ball and one to eject the ball and the breaker tripped preventing you from doing either why would you design your robot to only use one breaker?

To respond to Daniel above. I would have ruled the same. The current that flows in the red wire is the exact same current that flows in the black wire. As you described the wiring you could have had a single #18 wire passing the current of several 20 amp breakers and Spikes. For instance, 4 Spikes fed from four 20 amp circuit breakers each feeding say 10 amps would then cause 40 amps to flow in the #18 wire you daisy chained for the negative return leads. Potentially, 80 amps could flow in the #18 without any circuit breaker trip.

[Dad1279]

Update 8:
Each relay module must be protected with one and only one 20A circuit
breaker.

[Don Wright]

Still doesn't answer the question...

If multiple spikes are connected to a single breaker,
each spike is still connected one, and only one, circuit breaker.

Now, if they would have said:

"Each 20A circuit can protect one, and only one Spike.", that would be a different story.