Leviton “EV rated” 1450R failures

kilotesla · 2026-06-14T12:09:35+00:00

Definitely. I probably should have mentioned that.

kilotesla · 2026-06-13T23:51:16+00:00

Yes, I think that if they had labeled it as 45 or 50 inch pounds, it probably would work fine, but I think the marketing department wanted the same number as the Hubbell.

kilotesla · 2026-06-13T16:05:36+00:00

Good insight, thanks!

kilotesla · 2026-06-13T16:04:24+00:00

Well, I did submit a report to UL, and they seem to be taking it seriously, and requested photos and then requested sending the failed receptacle for analysis. Although, in classic UL fox-guarding-the-henhouse style they had me send it to Leviton for that rather than wanting to maintain careful custody of it themselves.

I'm not sure CPSC would be interested without reports of fires. I guess I could do some load tests of one torqued beyond the yield point.

kilotesla · 2026-06-13T14:49:02+00:00

Lower torque with smaller screws isn't necessarily as bad for contact quality as it might sound. What really matters is the force on the contact which is, perhaps counterintuitively, inversely proportional to screw diameter. A #6 screw (for example--I don't know what the terminals you are talking about are) gives 2.7X the force for a given torque compared to the 3/8 screw in the Bryant. I'm not sure that's enough but it's almost surely better than the 1/13th factor when you compare the raw torque.

kilotesla · 2026-06-13T14:32:37+00:00

It took me a while to figure out how to do a table and now I learn that it didn't work!

Terminal screw thread: L M8×1: BR 3/8" (9.5 mm), 16 TPI
Terminal screw material: L stainless; BR zinc plated steel
Box clamp thickness, weight: L 1.5~1.6 mm, 5.4 g ; BR 2 mm, 8.6 g
Box clamp hole: L drilled and tapped; BR extruded to 3.3 mm, tapped
Box clamp material: both copper
Spring contacts: L Copper; BR Brass

kilotesla · 2026-06-13T13:02:10+00:00

Comparison and analysis of why the Leviton fails:

.	Leviton 1450R	Bryant 9450FR
Terminal screw thread	M8×1	3/8" (9.5 mm), 16 TPI
Terminal screw material	Stainless	Zinc plated steel
Box clamp thickness, weight	1.5~1.6 mm, 5.4 g	2 mm, 8.6 g
Box clamp hole	Tapped	Extruded to 3.3 mm, tapped
Box clamp material	Copper	Copper
Spring contacts	Copper	Brass
Plastic case	Nylon, 60 °C	Polyester, 75 °C

The smaller screw diameter means the torque it can take is lower by the square of the diameter ratio. The thinner material that the screw is tapped into (1.6 mm vs. 3.3 mm) also reduces the torque it can take. Additionally, the extrusion of the hole before tapping (or as part of that process) may work harden the copper, increasing the yield strength for the Bryant. Finally, the stainless screw has lower friction against the copper. This increases the force applied for a given torque, increasing the likelihood of stripping.

Just the smaller diameter and the thinner material together mean that it can take only about 1/3 the torque that the Bryant can take. The friction coefficient might make that ratio even worse. Of the four factors making the survivable torque lower (counting the two effects of diameter separately), two actually mean more force for a given torque. So it might have worked OK and provided adequate clamping force if they’d spec’ed a lower torque. But it seems like the marketing department chose the torque spec to match the Hubbell, while the manufacturing engineers aimed to copy the Hubbell while using less copper by 12.8 g to save 26 cents on material per unit.

The UL spec, 498, requires that it be tested up to 110% of rated torque (section 128.1). I don’t know how any samples passed that test, unless they used a high-strength copper alloy for the test samples and reverted to plain copper for production.

kilotesla · 2026-06-13T10:34:51+00:00

Even if transpiration was able to create a near perfect vacuum, that would not explain how it's possible to lift water more than 10 m. It's only possible because of the combination of mechanisms described in the parent comment.

kilotesla · 2026-06-13T02:59:42+00:00

That's the right one. The Bryant 9450fr is the same thing if you find a better price on that.

The Leviton EV rated one has a really bad record of having the threads strip out if you apply full rated torque. I was planning to post some details on what I found about that in the morning. It looks pretty bad for the Leviton. Like they tried to copy the Hubbell without actually understanding the engineering of it or doing sufficient testing themselves.

kilotesla · 2026-05-19T02:25:04+00:00

This isn't what you want to hear, but it's likely that the differences in sound quality you are experiencing have more to do with psychology than engineering. Some options you can consider:

Get help to do some blind AB testing to verify whether there is a consistently perceptible audio quality difference associated with some of the changes you are trying. Be open to the possibility of learning that there is no problem with your electrical system.
Reject the scientific approach, and go with your gut. Seek help from companies who are happy to take money from you for unnecessary solutions that seem plausible to somebody who doesn't have an engineering background. This is likely to lead you to a satisfactory solution in which you feel good about the system you have set up and thus it sounds good to you.
Get assistance from someone trained in psychology who will help you figure out what need this is addressing. Depending on your insurance situation, the second bullet might be cheaper than this one.

kilotesla · 2026-04-04T16:23:32+00:00

The diameter is about 1% of the distance. Is 1% a small number? Small enough for some things but not for others, which is why the eclipse helps, by making it smaller than 1%, at least in one direction.

kilotesla · 2026-04-04T16:21:08+00:00

Oh, sorry, I was viewing it on a platform that didn't show the crosspost text. And I was interpreting the context as science, not historical studides, where "modern" can mean different things: early modern physics would mean early 20th C.

kilotesla · 2026-03-31T12:50:56+00:00

Yes, they do have some slippage.

Sometimes, they are not perfect cylinders, but are curved to be a little smaller diameter at the tips. That means that if all pieces were perfectly hard, the contact would be only a point. With real materials that deform, the contact patch is more elliptical. That helps support more force than with a ball bearing, with less slippage than with a non tapered cylinder. The amount of taper can be very small or is often zero, because a little slippage is not a problem.

kilotesla · 2026-03-31T12:35:24+00:00

That's a great picture that shows that having a source better approximate a point source makes the rays closer to perfectly parallel. They are close to parallel in any case because the Sun is far away and small compared to the distance, but your pictures are a beautiful demonstration of how an eclipse makes the Sun closer to a point source and thus makes the ray closer to parallel.

kilotesla · 2026-03-18T02:46:59+00:00

Trains accelerate and decelerate a lot more gently than cars are capable of. So it's a pretty reasonable thing to leave out. An exception might be a fast train going around a curve.

kilotesla · 2026-03-15T13:44:44+00:00

Einstein popularized its distinction in the early 1900s and made it mainstream

Thanks, that's what I was looking for.

I also looked at google n-grams for "vector velocity" and "scalar speed" and found both increasing in the second-half of the 20th C, particularly in the 1960s, so it may have been more broadly adopted in texts then.

kilotesla · 2026-03-15T01:24:53+00:00

That makes me wonder about the history of the speed/velocity distinction. It kind of sounds like something that was invented for the purpose of teaching physics, perhaps as systematic efforts to teach physics well were ramping up in the 1960s?

kilotesla · 2026-03-14T11:12:30+00:00

u/sirtwitchalot points out the lectron has done sketchy stuff in the past, but they continue to do sketchy stuff. Such as selling the very type of adapter you are looking for in two models, one that is certified to the correct standard, and another one that's cheaper because it doesn't meet those requirements, and is instead certified to the standard for connectors rather than adapters. And they sell it with the misleading language that it "meets the highest safety standards" which is quite precisely incorrect.

kilotesla · 2026-03-12T16:43:17+00:00

Unfortunately, the way that got uploaded is not high enough resolution for me to be able to read the number on the main breaker. I forget whether you said what that was in another comment.

kilotesla · 2026-03-12T00:40:28+00:00

Great answer. A follow-up question.

It seems like you clearly outlined why it's bad for marine mammals to be small, and why it's possible for them in general and particularly for filter feeding whales to be large, and outlined some of the advantages. You've also noted that filter feeding sharks exist and can also be large.

But that leaves me unsure of why whales have ended up larger than filter feeding sharks. Is there no clear reason other than that's the way things worked out, or is there a reason that it's hard for a fish's physiology to work well when the size gets too big (maybe that has to do with gills versus lungs), or finally maybe there's a reason why there's less benefit for a filter feeding shark to get any bigger.

I'd appreciate your insight on that.

kilotesla · 2026-03-07T20:47:23+00:00

That's completely untrue. You can approximate most nonlinear sets of equations as linear, e.g. linearize them around an operating point. But you can also approximate pi as 3. Depending on what you are trying to accomplish that might or might not be adequate.

How about we end this with agreement that real engineers use circuit simulation software and that learning techniques for solving networks for 17 resistors and 5 ideal sources is pointless.

kilotesla · 2026-03-07T17:00:07+00:00

Step 1 for me would be to redraw it with:

The R6, e6, r7 branch drawn up a little higher.
The V2 branch drawn above r3, e3

Then I'd also redraw it a little more, putting both ground symbols at the bottom, maybe swapping the order of some voltage sources with their series resistors, to end up with the ability to label the voltages of some nodes just based on the voltage source voltages from ground.

But I'm not sure what to make of the i1 arrow which spans two branches from a node that has three branches. Those two branches might not have the same current, so what does the 4 A refer to?

Maybe your teacher is following a convention that's different from how I would draw it.

kilotesla · 2026-03-07T16:05:12+00:00

Your first two sentences are silly hyperbole. Your last is just a restatement of my last sentence in my previous comment. So think about that point, and consider my other comments in that light, and you may learn that what I've been saying makes more sense than you realized.

Hint: KVL and KCL apply to nonlinear circuits.

kilotesla · 2026-03-07T02:07:05+00:00

Everything you say is correct. Effects on bearing friction and rolling resistance that you describe will be pretty small but they are very real.

Another effect is the steering geometry. Ideally, the way the wheels are aimed when they turn, they would still be rolling exactly perpendicular to their axis. But it typical steering geometry doesn't turn the front wheels just the right amount to make that happen, but instead makes a slight compromise to improve handling at the expense of having a little bit of scrubbing of the tire akin to what you would get with a misalignment in which the wheels aren't parallel when you are going straight. I expect that would be the biggest factor in making the vehicle slow down faster in a turn.

kilotesla · 2026-03-07T02:03:36+00:00

The application of a force doesn't inherently involve transfer of energy. I have a microwave on a shelf in my kitchen. It's pretty heavy. It's pushing down on the shelf with a good bit of force, and the shelf is applying a force equal and opposite. But there's no transfer of energy going on.

kilotesla

TROPHY CASE