verifying torque value NEC 70B ?

[christianrMadden]

Hello every one I'm watching the videos in EL theory and the panel kept referring to 70B for how the NEC wants us to verify our torch but I cannot find it can any one assist me on understanding this. For reference I am at EL theory unit 6, 10 min and 17 sec into video and page 42 in the work book.

 

[tom baker]

Torch?
What EL theory book?

 

[don_resqcapt19]

7.2.1.4.1
When using a calibrated torque wrench to confirm the torque of previously installed threaded hardware, the retightening value shall not exceed 90 percent of the manufacturer’s specified initial torque value.

The use of the term "hardware" makes me think this only applies to bolts that connect busbars or connect a lug to the busbar and not to a set screw that puts direct pressure on a conductor.

 

[christianrMadden]

Hey guys I feel really dumb after continuing in the video i realized these are different books that have different rules than the NEC and i thought it was referring to an article in the NEC sorry I'm a new apprentice and just trying to figure it out

 

[christianrMadden]

Torch?
What EL theory book?

mike holt understanding EL theory

 

[Joethemechanic]

Verify it using a torch wrench

 

[christianrMadden]

mike holt understanding EL theory

also i misspelled torque sorry guys

 

[christianrMadden]

Hello every one I'm watching the videos in EL theory and the panel kept referring to 70B for how the NEC wants us to verify our torch but I cannot find it can any one assist me on understanding this. For reference I am at EL theory unit 6, 10 min and 17 sec into video and page 42 in the work book.

hey guys I saw meant to say torque i apologize man im really making my self look dumb today

 

[Joethemechanic]

hey guys I saw meant to say torque i apologize man im really making my self look dumb today

Sorry I had to be a wise ass

1/4 in. Drive 20-200 in. lb. Click Torque Wrench

Amazing deals on this 1/4In Dr Click Type Torque Wrench at Harbor Freight. Quality tools & low prices.

www.harborfreight.com

 

[jim dungar]

hey guys I saw meant to say torque i apologize man im really making my self look dumb today

I edited the thread title for you.

 

[tom baker]

Torch?
What EL theory book?

Sorry missed the torque in the title
(That sounds like a movie title)

 

[christianrMadden]

Thank you!!!!! so I'm a lil confused so are the 70b and 70e i kept hearing in the videos apart of the NFPA or something and does the NEC not cover whats in those books?

 

[tom baker]

Or maybe it’s spell check. My county Kitsap gets corrected to ketchup

 

[don_resqcapt19]

Thank you!!!!! so I'm a lil confused so are the 70b and 70e i kept hearing in the videos apart of the NFPA or something and does the NEC not cover whats in those books?

The NEC is NFPA 70. 70B and 70E are also published by the NFPA. They are not widely adopted like the NEC is, but 70E is can be cited by OSHA under the general duty clause as it relates to worker safety.

 

[christianrMadden]

Wow I went back to felling extremally dumb I'm so used to the trade term NEC and never paid attention to what the book is actually titled. wow hopefully my lead Doest happen to see this ill never hear the end of it lol what article can i look up how to properly test for torque

 

[Joethemechanic]

how to properly test for torque

Put your torque wrench on the fastener and slowly increase how hard you pull until it clicks

 

[Joethemechanic]

 

[zbang]

There have been quite a few threads here about torque, but the main and often missed point is that you can't "verify" torque on a bolt after it's been set! Sure, you can put the torque wrench/screwdriver to it and see if it clicks, but all that will tell you is that it's loose enough to move, not that was correct; the only way to see that it's right is to loosen and tighten to torque again. (Look up "sticktion" for this.)

Snap-on has some words about the subject-

https://www1.snapon.com/display/231/ToolNews/TechRefs/2008/TorqueWrench08.pdf

 

[Joethemechanic]

Yeah tourque should be measured while in motion. Some other factors that throw touque values out the window are any damage to the threads, and anything applied to the threads (like oil) but it could be anything. Usually manufacturers will either say to torque clean and dry, or they will specify what the threads should be coated with. This is important because although your torque may be correct, what is on the threads alters the clamping force of the fastener

 

[hbiss]

There have been quite a few threads here about torque, but the main and often missed point is that you can't "verify" torque on a bolt after it's been set! Sure, you can put the torque wrench/screwdriver to it and see if it clicks, but all that will tell you is that it's loose enough to move, not that was correct; the only way to see that it's right is to loosen and tighten to torque again. (Look up "sticktion" for this.)

So, really there is no way to verify to an inspector that the fastener or lug has been torqued to specification.

-Hal