ECN Forum Forums Code Related Discussion NEC & other Code issues Torque

How does an inspector know if you torqued a termination to the proper amount when he makes an inspection?

They don't know and I can not see anyway they could unless they stand there and watch me do it.

Method 1:

He marks the position of the fastener, and using the proper tool applies torque to the lower limit.

If the fastener moves, he fails the job.

Method 2:

He requires a special inspection at the time of the instalation.

Method 3:

He requires a fastener where the head breaks off at the proper torque.

As an engineer I would require #2 or #3 and so state on the plans and bid sheets.

I sure would be interested to see any panels, breakers or busbars equipped with the breakaway heads.

I have only seen bus duct available with those fasteners.

As far as the inspector operating a tool that will not happen in my area.

They will not take on that responsibility and I do not blame them.

Who would pay for repairs if something breaks.

Or say the inspector was the last one to touch the terminal and 11 months later it fails for any reason.

In MA we are required to provide a one year warranty.

Who would be responsible?

If you try torquing down something that is already torqued you risk over torquing it, as in breaking it.

Around here, some inspectors dont care. Some want something in company letter head stating you torqued everything. Some want to watch you.

Lately I've started marking my initials, the amount I torqued it to and the date. Haven't had an inspector bring up torquing since.

I've seen a technique used to mark properly torque fasteners, which is to torque the fastener and then use a sharpie to draw a line from the center of the fastener off to one side of the surrounding material.

I've heard that a clueful inspector will understand this, and recognize it as meaning that the electrician actually took the time to properly torque the fastener. Of course it doesn't actually say what torque values was used, and nothing prevents someone from simply marking any random fastener.

I like the approach of recording the torque value that dmattox suggests. This permits an inspector to double check which torque value was actually used, and is a pretty nifty workmanship detail.

-Jon

I have never had the issue of proper torque come up; it seems to be a "detail for geeks", and some assure me that the worst that will happen is that the inspector will ask to see your torque wrench.

I don't understand the concern over re-torquing a fastener. If you have tightened it to, as, 14 lb-in, wouldn't applying 14 lb-in to it again have no affect? It's not like a hammer blow, after all.

If I did have a concern, or wish to verify the tightness of a fastener, it seems to me that the best way to do this is to see what it takes to loosen the fastener, then re-tighten it.

As an inspector all I can say is you don't know. I do check that they at least have a torque wrench on the job. If they use it, and if they use it properly, it is the installers responsibility not the inspectors.
If it fails it goes against the installer not the inspector. There are torque requirements for screws. Have you ever seen an electrician use a torqueing screwdriver when installing a receptacle ?
As an inspector you have to trust the licensed electricians.

[This message has been edited by Alan Nadon (edited 06-19-2005).]

It has an effect, and I say this from experience not from reading it somewhere.

Re-torque the lugs enough times and you will crush the conductors.

IMO most all of us, when tightening lugs free hand go far above the specified torque. Try using a torque wrench and I think you will be surprised how quick you here it click.

They say in what I have read that that over tightening causes the conductor to 'cold flow'.

[This message has been edited by iwire (edited 06-19-2005).]

If you torque something down, then immediately try torquing it again you will move the lug/bolt more than when you first torqued it, often substantially if the torqued rating is low. Worst case is that you might strip out a lug, nothing worse than trying to loosen a stripped lug.


I'd agree with that. I was torquing down some bussing with a helper a couple weeks ago. He was working with one of our other foremen saying they were using a wrench with a breaker bar. He was shocked with how little pressure was actually needed when you torqued it to manufacture's specs.