Another electrical inspection question

[philso]

Will the Inspectors require that all wire have the size visible (printed) on the wire?

I noticed last night that some of the wiring to the motor controllers was done using 12AWG wire that did not have the wire size printed on it. The reel had the wire size on it and the conductor size looked right when compared to wire of a know size.

Thanks.

[SenorZ]

Usually not in my experience.
What they do is look at the wires and ask a student to tell them what gauge it is. If the student can answer, and use the correct number, and it looks like the appropriate size, they're OK.

Again, that has been my experience at 4 regional competitions. Your results may vary.

[Matt C]

In the past when I've done robot inspection, we have a board with bits of wire stapled to it as reference for sizing.

[Taylor Hawkins]

Originally Posted by philso

Will the Inspectors require that all wire have the size visible (printed) on the wire?

I noticed last night that some of the wiring to the motor controllers was done using 12AWG wire that did not have the wire size printed on it. The reel had the wire size on it and the conductor size looked right when compared to wire of a know size.

Thanks.

We have never had a problem with that however if the inspector feels that the wire diameter is too small they can have you change that wire to something of the correct size.

What are you running with that wire? Are you right on the cusp of the amperage limit for that guage of wire or do you oversize all your wire?

[Andy A.]

While labeling requirements are not specifically called out in either the rules or inspection checklist, an inspector is tasked with verifying that wiring is appropriately sized. The most foolproof way to demonstrate that a wire is correctly sized is to have it labeled as such by the manufacturer. There is enough variation in insulation thickness that you really can't/shouldn't rely on outward appearance. An experienced inspector can probably size wire that way, and they are given examples as part of the training, but the burden of proof is ultimately upon the team should any questions arise.

Some wire may not have a size listed on it from the manufacturer*. If that's the case for your robot, I'd strongly recommend that you bring the spool that wire came off of, which should have the size printed on it, with you to competition. An inspector can compare the wire on the spool with the wire on the 'bot and that'll satisfy 9 out of 10 inspector concerns.

Andy A.

*Incidentally I'm not sure if the lack of labeling signifies a lack of some certification or class rating. I'd be curious to hear from any anyone who knows the ins and outs of wire sizing and classifications about that.

[Jon Stratis]

The burden of proof is always on the team. That's why we ask teams to bring data sheets for some stuff (like pneumatic components) - they have to prove the specs of whatever we're looking at meeting the rules.

When looking at wire, I can usually tell if a particular wire is the correct gauge. Sometimes, though, I'm not sure and I look for labeling on the wire itself. If the labeling isn't there, then the team will need to provide proof that the wire is the correct gauge - for this, the spool (with some wire still on it) with correct labels would probably suffice. If nothing else, I'll grab a set of wire strippers and strip a short (<1/2") section on a spare piece of wire to make sure it is the correct gauge.

I also always ask the students what gauge the wire is. It's something they should already know and be able to answer, and when they can't it's a teaching moment.

[philso]

The wire they used comes as a red-black pair with an overall jacket. The wire size is printed on the jacket. For our application (to and from motor controllers), we are discarding the jacket.

We can always bring a piece with the jacket that has the printing.

[philso]

The wire they used comes as a red-black pair with an overall jacket. The wire size is printed on the jacket. For our application (to and from motor controllers), we are discarding the jacket.

We can always bring a piece with the jacket that has the printing.

[DonRotolo]

Originally Posted by philso

The wire they used comes as a red-black pair with an overall jacket. The wire size is printed on the jacket. For our application (to and from motor controllers), we are discarding the jacket.

We can always bring a piece with the jacket that has the printing.

Do that, with the wires still in the outer jacket, so the inspector can see it.