verifying torque value NEC 70B ?

[letgomywago]

And now for confusion, it’s newton meters for torque.
It is important to torque lugs, get a torque wrench and use it. Klein makes a 3/8 and 1/2 drive version

The cost of those keep people away. I always point out the harbor freight has 20 dollar torque wrenches that are pre calibrated with documentation. When you send them in for testing and calibration they still come back good to go.

 

[letgomywago]

I just spray and rattle tight with impact, , farmer tight.

That's what the POCO guys do but pulling out the fancy tools makes the job look more important and covers your butt

 

[Joethemechanic]

I just spray and rattle tight with impact, , farmer tight.

Just weld it all together with lots of 6011 rod, screw the next guy

 

[Crash117]

Just weld it all together with lots of 6011 rod, screw the next guy

Thoughts on this torque screwdriver??

Amazon.com

 

[Joethemechanic]

Thoughts on this torque screwdriver??

Amazon.com

I've never used one, but it looks handy. If you don't have to go tighter than 50 inch pounds I don't see why not.

 

[Crash117]

I've never used one, but it looks handy. If you don't have to go tighter than 50 inch pounds I don't see why not.

Most breaker screws are rated 50 inch pounds or less. Only main lugs or larger terminals tend to be higher than that. For circuit panel torque, it looks to be ideal for breaker tightening

 

[gar]

230618-0236 EDT

It is not "inch-pounds" that is a measure of work. The correct units are "pound-inches", like "newton-meters".

.

 

[TwoBlocked]

Here's the one I got. I like the t-handle for the higher torque settings. You can either get 2" long bits so as to reach everything or use a narrow extension. Hard to find slotted bits that are a decent size for larger screws. McMaster-Carr has a good selection. I thought a torque screwdriver was silly until I had to answer for a wire popping off in an awkward place at a gas compression station. (In a non-classified control room). Then I started checking breaker panels here and there and wowser, what an eye-opener:

Amazon.com

 

[letgomywago]

Here's the one I got. I like the t-handle for the higher torque settings. You can either get 2" long bits so as to reach everything or use a narrow extension. Hard to find slotted bits that are a decent size for larger screws. McMaster-Carr has a good selection. I thought a torque screwdriver was silly until I had to answer for a wire popping off in an awkward place at a gas compression station. (In a non-classified control room). Then I started checking breaker panels here and there and wowser, what an eye-opener:

Amazon.com

Looks nice

 

[Sberry]

Just weld it all together with lots of 6011 rod, screw the next guy

The worst are tire stores, zip,,, hot and fast and dry. The reason they use dry anymore is 2 reasons, first is they cant get all the chimps to do it the same way and second some juice on the faces of cone nuts lets them drive too tight especially when guys make several passes with the gun. Not so much a problem when so many did uit by hand back in the day and new bat impacts can really hit instant like and dont have the feel air can have. I sneak up on some and finish them by hand but I also test some. Out of 20 the other day I had one about 10 over and one 10 under.
Obviously before someone says it,,, it is estimation but its a pretty good one.
I got to watch it a little, I been using the same air gun a long time,, put a new anvil in it and hits like it was new again. I have had it happen a couple times over my career, my helper zipped one on and I had a real field problem.
As for directly related to electric,, how can it be good when a guy installs a white wire in a new panel and before it even gets snug it squeaks? I really cant believe there is an engineer at SqD says,,, lets design this for a dry torque on alum threads ruff enuf they squeal from hand screwdriver. I was in one the other day outright ruined it.
I will probably catch some spit for this but I really dont care,,, we use a little no lox on all lug threads, in meter cans, on mains all of that and give the N bars a little sprinkle of WD40 or the like, can outright feel the difference in screws, some can barely turn right out of the box. Couldnt retorque a screw if you wanted to, they stuck the first time out. But,,, I am about sure that will bring some kind of argument about how that is a good thing or some genius tested it that way.
Way early in forums before it was well established there was one dedicated to bolt tightening, it was very dry, one engineer said,,, some will never learn. Was kind of a shame considering the zillion fasteners of the world.
A good book should be in most trade classes is the John Deere fastener manual comes with their training material. Everyone using tools should read that. While there are more complicated theories in it the one point they make is it stopped turning doesnt mean it clamped anything and a dry screw is totally unpredictable in that regard.

 

[don_resqcapt19]

This is really important. A dry sticky thread really cant be tightened correctly which is totally different than the torque required to turn a bolt.
I saw a test from a trade show among apprentice types. 25 guys, 1 got it right. Guys thought 7# was 25 and several were at 12. It used to be that engine work was routine, cars often needed valve grinds at 50K, all those parts were torqued and guys learned and got a good feel. Lots of kids did lots of engine work, 6 graders fixed mowers and now a kid hasnt used a screwdriver till the day he sign up for apprenticeship.
About the only time we use the wrench is engine work, something with a real spec and even those head bolts for small ones simply do by feel.
Wondered wtf the other day, someone read spec wrong and found it by feel in a double check.

Yet, unless the torque specs specify lubrication, you need to torque the electrical termination with dry threads. The same torque value with lubricated threads will produce a much greater crushing force on the wire, than with dry threads.

 

[don_resqcapt19]

Do you have something I can use for a reference? I have a hard time justifying downtime. Interrupting a process for a minute or two is usually no big deal. Ten minutes to remove, cut, strip and retighten means product is going to back up somewhere

From IAEI Magazine:

Both loose and overly tightened connections create a risk of failure. Neither equipment manufacturers nor industry standards recommend periodic retightening of connections. Even when a “hot” connection is detected during an infrared inspection, simply tightening the connection probably will not correct the deficiency. The connection must be disassembled, cleaned and reassembled with the proper tool and torque. Additionally, cutting off the previously connected end of the wire and making the connection with an unused section of wire is the safest solution.

 

[Joethemechanic]

From IAEI Magazine:

Thanks.

Another uphill battle to tackle. We have upper management in the maintenance department who are supposedly engineers who think that a squirrel cage induction motor running across the line turns slower when it gets "Old and tired". They also think that a boiler feedwater deaerator tank can operate without a vent

 

[zbang]

Old and tired? Well, without cleaning and oiling, it just might turn a little bit slower, but probably not so much as anyone would notice.

Problem is that a lot of these people just don't think at all.

 

[gar]

230618-1226 EDT

When a screw is used to fasten a joint you generally have no way to directly measure tension in the bolt, but this is what you want to control.

The usable measurable quantity is torque.. Torque as a measure of tension is a very highly variable factor. Special coatings on fasteners when properly applied, and used to be fairly useful until banned by the government. Generally a small amount of a wax like coating was also added.to reduce friction. Only when this whole process is well controlled do you get a useful result.

I built gaging equipment that controlled or monitored pinion preload on possibly 100,000,000 automotive differentials. These nuts had a certain amount of wax on them to reduce friction. In the manufacture of these nuts a thin wax coating was added. This coating along with the type of plating had to be reasonable well controlled.

Something I was not envolved with was wheel bolts. At some plant some one made the suggestion that wheel nuts should be lubricated. This was put into production without changing the torque specification. The net result was wheels falling off cars as they were driven.

. ..

 

[Joethemechanic]

Old and tired? Well, without cleaning and oiling, it just might turn a little bit slower, but probably not so much as anyone would notice.

Problem is that a lot of these people just don't think at all.

Yeah it was all about poor pump performance. Motor was about 25HP turning a positive displacement pump. They replaced it, problem persisted, Then they asked me to verify ""The fields were wired up right"" . Keep in mind no high current. So then they replaced the pump, no change,. Oh and this pump has a gear reduction box between the motor and the pump. They wanted to replace that, but before that could happen me and the kid I was working with decided to tear the suction line apart for a visual inspection. Kid finds a suction hose that was damaged inside and collapsing.

Then there was the $750,000 in gearboxes some big shot bought and installed on a timed machine that "Should be ok because the ratio is only a few points off". Yeah it was ok for like 30 seconds of that line running. Took them days to figure out that the only solution was to put the old gearboxes back on. BTW the old gearboxes ran for years until the line was replaced

 

[Sberry]

I did 100 the other day, it was on home I own. Insp must have looked at the permit and seem homeboy, he pulls out his big fat stub screwdriver (same one I used) and said,,, very good. I had never met the guy, after he give me a green and said,,,, looks like you may have done this before (city water, gas) steel incoming pipe.
Great guy, very good inspection related right to the scope on the permit, I left the old fed panel laying there where it could be seen, he says, we call those welders,,, ha. We even had a little chat about electric demand, he must have noticed I replaced 100 with 100 and I mention I removed the electric range and installed gas. He says,,, good to go.

 

[Sberry]

Yet, unless the torque specs specify lubrication, you need to torque the electrical termination with dry threads. The same torque value with lubricated threads will produce a much greater crushing force on the wire, than with dry threads.

It would be if we used a torque wrench. Like I mentioned earlier, problem isnt cominng from over tightened crushed wires, it coming from limp writed types not having a clue wat feels like its tight right. I cant ever remember a service call where the problem was a crushed wire under a screw???
Never ever not 1.

 

[Sberry]

Have had wires loose under seized screws and dozens of loose screws. Had a recent one from 2 wires under the screw.

 

[letgomywago]

It would be if we used a torque wrench. Like I mentioned earlier, problem isnt cominng from over tightened crushed wires, it coming from limp writed types not having a clue wat feels like its tight right. I cant ever remember a service call where the problem was a crushed wire under a screw???
Never ever not 1.

I took apart an ac disconnect that someone at the same company installed a week before to see they had impacted the wire till it pinched the wire and it snaped under load.