So I just received some PowerPoles which I had ordered in the mail, when I noticed a problem: the connectors I ordered are rated for 30 amps, but I had wanted to use these to supply motor power to CIMS which are wired off the 45 amp PDP slots.
Now I was kinda bummed, since these took a while to ship and were pretty expensive. I checked out the info on the PowerPoles I ordered, and found a paragraph which suggests that using the 12- gauge powerpoles for 45-amp current would be fine- it reads as follows
“The size of the wire a Powerpole contact will accept is the primary limitation of their ability to carry a load. The size of the flat contact area is actually the same for all 15, 30 & 45 amp contacts. Powerpoles will safely handle higher loads or surges, please read the PP30 data sheet (PDF) for additional information”
I went to check out the datasheet and I’ve looked through the entire thing- the only reference to current I can find is an entry called “UL Current Rating,” which just seems to be restating the 30-amp recommendation, and some graphs. I couldn’t find any references to “max current” or “surge current” or anything. The graphs don’t do much to clarify the situation- I went through and compared them to the 45-amp PowerPole datasheet, and if you compare the two it looks like the 30-amp PowerPoles actually have a lower temperature rise for any (shown) applied amperage.
Anyways, what this boils down to is I would like an affirmation that using the “30 amp” (In quotations because their actual safe load is unclear to me) PowerPoles are safe to be used in 45-amp circuits (with 12 gauge wire). Anyone have enough experience with these to enlighten me?
My team uses the 45’s. I’ve had good luck ordering both contacts and housings from Mouser and Allied Electronics, with decent shipping time from both vendors (i really wish Digi-Key carried them, as shipping here is about 1 day for them!).
Having had 15’s, 30’s, and 45’s in our shop, I can tell you that the issue really comes down to wire size. If you have one of the standard PowerPole crimpers, it could have trouble with a 12 gauge wire in a pp30 contact.
From an inspection standpoint, I would be unable to look at your robot and tell the difference between the 30 and 45’s- once the wires are in place and they are in the housing, there’s just no way to know.
Unfortunately, I don’t know quite enough to know if it would be safe or not to use them - that’s why I rely on company listed ratings on parts. To me, having a part that is “rated” for 45 amps sitting being a 40 amp breaker is safe… Having one that is rated for 30 amps behind a 40 amp breaker is taking a risk. My guess would be that the risk is minimal, as we run short matches with long cool down times, and you rarely reach currents into the 30’s for extended periods on a normal robot. That should mean the contacts wouldn’t have enough time to get hot enough to cause problems. But I’m not willing to bet the success of my team (or the trigger finger of the FTA with the fire extinguisher) on it!
We went through the exact same thing two years ago. For us it was even worse, because we had a mix of 12 gauge and 14 gauge wire. (I later threw the 14 in the garbage and swore to never buy it again; you think you can train students, but… :)).
We did have one of the 30 amp / 14 gauge wires melt the powerpole housing. I’m not sure if it was because we were over spec, or if it had been badly wired. But it was a clear cautionary tale, and made me examine what the students had done, and so figured this out.
What we did was put in 30 amp breakers and explain the situation to the inspector. He was puzzled, but passed it.
So, long story short: I know exactly how you’re feeling. But if I were you, I’d order a big bag of the 45 amp poles, and get expedited shipping. Side bonus: they are easier to crimp :).
Could you post a link to which particular powerpoles you purchased? There are a couple of different product lines with the powerpole name, and it would help to know exactly what we are looking at.
The 30A powerpoles will work just fine once crimped and housed. The contact area is the same and they’ll behave identically to the 45A connectors. They might be a bit of a pain to connect to 12AWG wire since they have a closed barrel, but once you do so they’ll be fine.
I don’t know if contact area is the same, but contact resistance is higher with the PP30s over the PP45s. Per spec on a 12AWG wire, the PP30s will rise 30C at 30A while the PP45s will rise ~17 in a single pole configuration. In multipole, the charts don’t go up that high for the PP30.
I’d like to know how that happened. By any chance was it in a block of 4 or otherwise covered/insulated?
In general, we’ve stopped using the PP30s & 14 AWG for FRC. I gave all those supplies to our FTC team. We never used it as we just spec’d 12AWG and never revisited if we could get away with 14AWG.
Side note, I’ve got a around a thousand PP45s and access to a post office.
We used the 30 for everything except for the motor controllers themselves. The newer motor controller wires will not fit into the 30s, but regular 12 gauge wire fits fine. We like the 30 because they are easier to crimp - you just slide them on, slip it in the tool and crimp. The 45s take a little more balance and coordination.
I don’t recall the details. We were not grouping in blocks, so I don’t think it was that.
It was in the waning hours before bag day, so we didn’t have time to really triage it.
My instinct was just like others here; that it should be safe. But my recollection is that a programming or mechanical error caused us to push max current through a CIM for an extended period of time (perhaps 5-10 seconds, not minutes). When I was brought over, I saw the cause of the max current, and then saw a slightly melted powerpole housing. As I investigated, I realized that the students had done a small amount of the wiring with 14, and then I also realized that I had bought ‘30A’ poles for all our wiring.
I recall feeling that I was not certain that the 30A poles were the cause of the melting, but that I could not honorably rule it out either.
(And yes, to Jon’s point, it would have been much easier to leave it alone; the inspectors would never have noticed. And it took us easily 5 minutes to explain why the 30A breakers to the inspector that day…)
@#@#@#@#, I either need more coffee or more sleep. I was looking at the solid line for both of those, and I had even noted I needed to compare solid to dashed.
Realize ratings have a lot of assumptions built in. Sustained use and long term durability act as derating factors. The difference between the 30 & 45 amp connectors are more about the wire gauge the anything else. I would use the connector that gives the best crimp for the wire you are using without trimming strands to make it fit. I suspect this logic is why we use a 50 amp power pole for the battery which pulling way more than 50 amps at times.
Guys,
The temperature rise is over a specified period of time, for UL ratings that is 24 hours at **continuous specified current. **The 30 and 45 amp contacts are interchangeable on FRC robots, as other have pointed out, as they have the same contact area. Temperature rise is also a function of the size of wire that is crimped to the contact. #12 or #10 will draw away greater heat from the contact than #14 wire will.
In nearly 100% of the failed contacts I have examined, the excess heat was caused by a contact not being fully inserted in the housing, or a poor crimp on the wire. Anything that will increase the series resistance of the contact will increase the overall heat. This holds true for any style including the WAGOs on the PDP, the SB50 on the battery leads or the motor controllers and motors.
I did find one contact that had been used and abused repeatedly and that contact had worn through the housing due to the excessive movement of the wire and loose contact spring. It eventually made contact with the other conductor in the two block housing. The resulting short created the heat.
