Tightening Torque for Screws

[hashim]

UL 486B, table 21 talks about the tightening torque for screws. What is the significance of A and B value in the table. Is it the tolerance limit for the tightening torque? Can any one help me out?

 

[Pierre C Belarge]

Very few of us actually have any of those documents. Maybe you can post some of it so we can see what it actually says. This way we can all be as confused as you are. :grin:

 

[jim dungar]

I have never seen the UL486B table you are talking about. However, in a different UL standard the torque tables for slotted screws have different columns for different slot sizes.

 

[Rockyd]

I've always used the chart in the NECH in 110.14. Now before anyone can say NECH is not code, the notes explain that this is the chart that UL uses...thus making it codeworthy. Anything technical will have it's own listing in the instructions per 110.3(B).

 

[Pierre C Belarge]

There is a very small percentage of individuals who are actually torqueing the terminations these days.

Of the ones who are not torqueing, I would lay odds that most are "overtorqueing" the terminations they install.

 

[Rockyd]

Wait till everyone has to start following the ad nauseum regulations imposed upon the oil industry. Torquing is just the beginning (EVERYTHING gets torqued). One has to have a cast iron stomach at times to face "rules put upon the industry". Sure, I want a safe work environment, but I want reality to be my guide lines. Not in bed with the oil companies, but they have wrote a lot of my checks. It's surprising that we don't pay more for gas. Just look at what they pay in Europe.

 

[LarryFine]

Of the ones who are not torqueing, I would lay odds that most are "overtorqueing" the terminations they install.

Would stripped threads, broken screws, and cracked insulators be a sign?

 

[brian john]

Of the ones who are not torqueing, I would lay odds that most are "overtorqueing" the terminations they install.

OHHHHHH you would win that bet.

 

[Pierre C Belarge]

Would stripped threads, broken screws, and cracked insulators be a sign?

Yeah, something like that. :grin:

 

[Pierre C Belarge]

OHHHHHH you would win that bet.

Brian
Now all we need is a few suckers so we can make some hay!:grin:

 

[nolabama]

would a torque screwdriver be worth it - you guys say only a small precentage of electricians use them - they are only a couple hundred for the nicest ones

 

[76nemo]

would a torque screwdriver be worth it - you guys say only a small precentage of electricians use them - they are only a couple hundred for the nicest ones

There's a place on ebay where you can get a Wiha 20-50lb driver for less than $90,.....new.

 

[Pierre C Belarge]

How do you use that torque screwdriver?

Do you chuck it up in your holehog electric drill for fast work of it?
or
Do you chuck it up in you battery dril?

:grin:

 

[frizbeedog]

I use German Torque......

















Gudentieght.

 

[76nemo]

Pierre, if you are asking me, I am referring to a handheld torque screwdriver. I have a 3/8'" torque rachet drive that I use if I have to redo a service. I have another friend that uses torque mark/paint that I am considering using. I haven't used it yet, and I know my local inspector will question it. I really like the idea, but I don't know anyone locally who uses it, we'll see how it goes. I figure I could use it at the meter line and load side and at the main.

Anyone else here use it? Why not?

 

[electricalperson]

i have the klein torque screwdriver and a couple klein torque wrenches. i dont torque screws on receptacles or other devices. i torque connections on breakers and service equipment. i do torque connections on certian devices. most residential devices dont get torqued

 

[nakulak]

I have a 1000v torque screwdriver I bought on ebay last year for 65 bucks - its not good for 1000 v anymore but works great and I like the fact that I'm now less likely to overtorque screw connections on gear and such. I use a small and large torque wrench for assembling any sizable gear. I really like having the torque screwdriver around.

 

[electricalperson]

i get funny looks when i break out my torque wrench and screwdriver but it keeps me warm in fuzzy on the inside knowing my connections are not crushed

 

[hardworkingstiff]

Does a torque screwdriver need to have the calibration checked? If so, how often?

 

[76nemo]

Does a torque screwdriver need to have the calibration checked? If so, how often?

Good question. Your local may not even require it's use, let alone it's cal increments. This is better answered by manufacturing spec's of the equipment you maintain.