The instructor at my last code refresher class talked about
properly torquing wiring connections. He said he went through a
building one time checking the connections. Few or none were torqued
I'm just curious if any of the pros here actually torque connections.
A quarter turn from breaking the screw is how people in my acquaintance
do it. Me included.
How would you know when it's about to break?
I've heard anecdotes about people put wire nuts
on with pliers, cause the instructor tests em
all, and tries to undo them. I often have to do
two wire nuts. I put electrical tape over the
both of them, for extra protection and also to
help keep them from twisting off.
Do you mean actually using some sort of tool (like a torque wrench) to
twist a wire nut or turn a screw to the proper torque setting?
No, no one on the face of this Good Earth does that...
..except perhaps for the instructor of your code refresher class.
Me, I just twist the byjeezus out of the wire nut or screw. I only stop
turning when I'm convinced that further twisting is gonna break
But, then I'm not a pro; I just pretend to be one whenever I'm dealing
with someone who knows less than me about a subject.
My Crouse-Hinds panel has a label inside the door specifying the torque by
both wire size and by wire way size. It also notes that the user should
check the breakers themselves for the torque specified by the breaker
If the termination is phillips, or blade, there really is not a need since
max torque is easily achieved.
Using nuts and bolts and/or allen head, all the time. I always carried
around one of those all in one handbooks from Ace Hardware. This book
is like a little almanac for "you name it". In this book it has a listing
of torque tables for size and grade of different size bolts. Plus the
conversion formulae for converting to and from inch pounds (usually what terminals
and lugs are listed under). I also managed to get a listing of all the
inch pound torque specs for Burndy lugs (ubiquitous) and used this as a
bookmark. Look up the size of the allen head and figure out the foot pounds
of torque for the torque wrench.
Usually it is not under torquing, but over torquing that is a problem. Some
of the lug housings may be split rather easily, and when you split a hard to
get lug on a $1000.00 plus circuit breaker or motor-starter for the first time,
that little torque wrench in the tool box becomes your friend when it comes to
the final five seconds of an install turning into a couple of days waiting for
one stupid lug to be located and express shipped.
Some lugs have very short set screws. I hate them. Unless you are maxing the
barrel out, putting the proper torque will drive the set screw past the threads.
Since the thread counts and dimensions are rather universal, I kept a supply of
the most common sizes in allen type, extra long. I'd pull the short ones and
toss them in the trash. I also kept a supply of the most common types of
lugs I might encounter in a grab box, in sets of four. There are certain things
that seem stupid to keep on hand at all times, but when in need. Hell, I bought
a wire fed welder for those moments when drilling and tapping just plain sucks.
Damn, I ran out of 3/8's bolts or strut nuts. It is metal, weld the beotch.:-)
Lugs are not structural and the lug is not steel. The handbook torque
values are likely way too high.
That is a good source, but the torque recommended by the manufacturer of
the lug should be used.
I seldom use a torque wrench unless the wire is quite large.
I believe that is correct. Aluminum, in particular, can compress and
"creep" with too high a torque.
What a great idea. You start with an engineered lug where expansion
rates are critical for a reliable connection, and replace the screw from
elsewhere. Steel would be a particularly bad idea.
Did you install the lug that failed for Danny?
You shouldn't drive the screw past the threads if you are using a wire
size within the rated (minimum size) capacity of the lug.
Um, the term ubiquitous was used. Do you know what that word means in the
Oh, you so funny. The replacement was from an engineered lug. It is just
a bit longer.
You would be surprised. Not all wire is equal. Locomotive cable compresses
more readily than standard copper wire. When using crimp terminals we often
soldered them afterwards. The fine strands have a way of working loose, even
after max compression with a hydraulic crimper. Not all of the terminations
I had to make were static. Vibration and movement are present. My work was
not residential, it was industrial. Regardless, I still had lugs bottom out
using a conductor well within the lug's rating. Do not approach me as if I
have minimal experience with such things, it is rather arrogant of you.
You included "allen heads". And I read the original question as torquing
Only way I can read it is you use the Burndy torque for other
manufacturers. As I wrote "that is a good source, but the torque
recommended by the manufacturer of the lug should be used".
Not at all obvious from what you posted. That means you are getting set
screws from other lugs, either recycling from junked lugs or junking new
lugs to get the setscrews.
Technically the lug is no longer UL listed. But ignoring that, I don't
ever remember ever having a set screw bottom when using a lug designed
for the size of wire.
"110.14 Electrical connections
Connectors and terminals for conductors for more finely stranded than
Class B and Class C stranding as shown in Chapter 9, Table 10, shall be
identified for the specific conductor class or classes."
(Also appears in 690.31-F for photovoltaic.)
If the setscrew drives past the threads with locomotive cable you are
probably not using lugs designed for fine stranded cable.
I approach what anyone says based on the accuracy of what is said.
Some of what you post has problems. Most is quite helpful.
I read about some American researchers working aboard a Russian
scientific survey ship and they were amazed at the Russian ship's
engineer who was able to get things to work with incredible feats
of improvisation. I too had to make a lot of my own parts doing
industrial and government contracting work. "We look for things, we
look for things that make us go" (The Pakleds from Star Trek TNG) ^_^
Some of the best work-arounds/inventions came via the "un-educated".
Hell, WWII pilots and crew modified planes in theater and said FU to
those who needed a "why" for adding to or modification of what seemed
like a perfectly functional aircraft.
Those whom questioned saw how things worked and designed in field mods
into future variants without credit.
I liked the story about how the designers wanted to know where all the
damage was on the planes that limped back home so they could reenforce
those areas. The guys on the lines told them to forget that, but
rather to reenforce all the areas with no such damage. Those are the
places that got shot up on the planes that *didn't* make it home.
I have repaired office machines since 1975... my entire life
I believe most experienced techs get a feeling for how tight to make stuff..
max torque is sometimes a bad idea, the next service trip may make it impossible to get whatever apart....
frankly i hate stuff thats been over torqued.
I have had dumb customers tell me with pride:( i always know when allen screws are tight, they make that click click click sound.
lucky me has to drill out the allens or in some cases use my sawzall to cut off shafts that i cant get apart:(
my goal is a quick low cost repair.....
idiots can make that impossible
over the years I have made lots of improvements to machines:) some of which have been adopted by manufacturers:)
Although the manufacturers engineers usually dont like suggestions from techs:(
who knows better what fails frequently but can be altered to work much better:)
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