Torque Requirements

[glene77is]

We all torque our connectors, bolts, etc.
Since I don't have any paying work until Monday,
my mind drifted onto the various torque specs we apply.

Everybody from iWire to Fine to Jreaf can list torques.

My question is related to such smaller items,
such as for a Wire Nut. (I have the answer for this one).

Does anybody have an idea what torque is available
from a good right hand screwdriver
(in a good right hand, of course) ?

Does the available torque change
when you change from a cross (Phillips) tip
to a slotted tip,
to a square (Robertson) tip?

:smile:

 

[SEO]

The only way to find out is use your torque screwdriver. If I get a chance I'll try mine. I think that mine only goes to 36 inch pounds.

 

[glene77is]

The only way to find out is use your torque screwdriver. If I get a chance I'll try mine. I think that mine only goes to 36 inch pounds.

That is a good way to find out just how big a hand you have.
I have twisted a barbell with a weight attached and found I have about 40 inch pounds, comfortably, with my arm extended straight out.
I suspect that some of the guys will have much greater 'twist' strength.
I worked with an Italian in '59 who liked to bet on who could install and twist the heads off of the most 1" by #10 PHSM screws, arm extended straight overhead to the joist.
I also worked with a German Mennonite with hands the size of my feet, no contest!

What are the torque requirements for a 'wire nut' ?
Do we have any requirements ? or just guess ?
Do we just twist until it will not twist any more ?
Do we just twist until it grabs all the wires ?

Like I said, I don't go back to work until Monday!

:smile:

 

[LarryFine]

Glen, there are too many variables to really come up with a definitive answer, such as metal hardness (both drive tip and screw), size of driver handle, strength of user, etc.

I can give an opinion, which is that square (and Allen (hex)) seem to do the least screw damage and thus provide greatest torque, with the usual proper-size-and-fit caveat.

Added: I used to really like Philips head drives, but either I'm getting stronger or they're using softer metals these days, but Philips and slotted drives just damage screws.

 

[nakulak]

Read the directions on a box of wirenuts

 

[LarryFine]

Like I said, I don't go back to work until Monday!

Now I understand the "Idle hands are the devil's workshop" addage a bit better.

 

[glene77is]

Larry,
Always liked your sensible answers.

"...variables ..."
Fair Enough approach.

"...an opinion..."
Properly labled, and I will always give an ear the "opinion".

"least screw damage"
Certainly a good subjective test.

... Philips and slotted ...
I find the Phillips slips out, requires greater push, and causes greater damage, than the slotted.
But, I grew up in the 'slotted' era, (50's),
before Phillips, and long before Robertson (square).
You do remember the 50's ?
That is when "TW" was the best insulation around,
when #14 Romex was standard for recepticals,
when before Romex had to have an EGC,
when we carried a Phillips in the tool bag.

There are torgue specs for each size of steel machine screw. Generally they range from 20 inch pounds to 40 inch pounds. 40 is what I can comfortably produce with the extended arm. My other post refers to my Mennonite friends with hands the size of my feet, and that is not a contest. The point being that one good hand turn may be the max spec'd for a machine screw. Two handed twists may being doing damage, like stretching the threads.

I would guess that 'idle hands'
might produce 3 inch pounds,
which is about enough
to pick up a full, cool, slick beer can.
( Since I do not drink, period, I am just guessing. )

The Torque requirements for the "WIRE NUT" do exists!
Care to take a stab at what they are???

:smile:

 

[glene77is]

Read the directions on a box of wirenuts

Sounds Right on the MARK!!!
Refer to the manufacturer's specs, somewhere.

After Larry answers I'll tell you what and where I found it.


:smile:

 

[PetrosA]

The Torque requirements for the "WIRE NUT" do exists!
Care to take a stab at what they are???

:smile:

I'll be curious to hear this answer. When I started twisting reds, I was about 13 years old, so '83 or so. I'd get them on hand tight which for me is pretty tight. I've noticed since I got back to twisting that reds are actually smaller than they used to be. I thought it was me at first, but I started getting pain in my thumbs and felt like I had to use pliers to really get them tight on more than two conductors. At some point I was in a building that had been wired maybe twenty years ago and untwisted a red. Wow, I thought, this "feels" like a red. Sure enough, when I held it up to a new red, I could see the difference. I didn't have my micrometer, so I couldn't tell you exactly how much smaller they are, maybe about 3/32" or so at the wide end, but it was a lot easier twisting the old reds vs. the new ones.

 

[LarryFine]

The Torque requirements for the "WIRE NUT" do exists!
Care to take a stab at what they are???

No, I don't like stabbing; I prefer using the terminal screws. :grin:


I really have no idea, except how much the wires get twisted.

 

[glene77is]

OK, guys,

Since I don't have to work until Monday (or Tuesday),
but I have to leave on an errand at 7:00AM,
I will get on with it.

Once upon a time, I was 'confronted' by a master who claimed I was 'over-torgueing' my Wire-Nuts, and 'under-torqueing' my Machine-Screws for JB covers. We didn't see 'eye-to-eye' then, and do not even have to look at each other now. That is about the time that I first joined the Mike Holt forums, and was awakening to the wide world of real electricians, engineers, physicists, and the like that we see in these forums, and from whom I have received much encouragement to explore, and an occassional rebuttal.

Now, for the Wire-Nuts, I simply read the manufacturers instructions off his web-site.
They refered to torqueing the devices until 'two turns of wire' are visibly twisted beneath the skirt. No 'pre-twist' was required. I usually 'pre-twist' in locations where I do not ever want to return (like under a house). Commonly, I line up the stripped ends, insert the device, and twist gently until I feel the threads grabbing, then start the torqueing, about 10 half-twists, which usually causes the wire to be visibly twisted below the skirt. Sometimes this means using the pliers, or one of those little Red Wire-Nut Handles (Little Red Things, or "LRT").

The manufacturer gave the specs as
torqueing the devices
until 'two turns of wire'
are visibly twisted beneath the skirt.

This approach to such a simple task may seem like over-kill, but it makes me feel good.
The copper alloy they use now is much harder-drawn than the copper used in the 50's. It is more likely to be forced apart when the joints are packed into the JB.

As an aside, this 'hard drawn copper' is good reason to use the Back-Stabbed/Clamped Recepticals. On occassion I have even transitioned to Stranded for the actual device attachment (I am pulling solid in conduit, and making a joint to include a stranded pigtail for the device).

:smile: