On May 17, 2:33*pm, "TomR" wrote:
TomR wrote:
In an earlier post of mine about adding a second neutral/ground bar
to a Siemens Main Load Center electrical panel, I posted the
instructions for doing that:

"Here is a link to the ECCNB16 Instruction Sheet which shows this
neutral bar
kit and how to install it:

http://www74.zippyshare.com/v/43794674/file.html."

In Step 4, on the right hand side, it says to tighten the two screws
using 40-45 lb-in of torque.

I don't have a torque wrench, and I would rather not buy one just for
this unless I need to.

My question is, about how tight if 40-45 lb-in when it comes to
tightening these screws?

....,

Thanks everyone for your replies. *I think I now have a fairly good
understanding of what 40-45 in-lbs means, so I think I'm on the right track
by just tightening the screws so they are definitely tight but not
overtightening them

Using the concept of about 4 lbs of pressure on a 10-inch bar (or a little
less on a 12-inch bar) gives me a good idea of what they mean. *I can do
that.

About the size of the screws -- the kit says it comes with two 1/4-28 x
13/32 screws. *So, I think they are 1/4 inch screws, 28 threads per inch,
and 13/32 in long. *They go into the same threaded holes in the neutral bars
that the rest of the regular neutral and ground wire attaching screws go
into.

TomR-

You exactly correct... they are 1/4 inch screws with 28 threads per
inch (fine thread)

Think about the torque in an equivalent wrench or ratchet situation.

With your hand on a wrench or ratchet at ~12" from the screw center
applying 3-1/2 pounds would give you 42 in-lbs.
With your hand at 6" you'd need to apply 7 pounds to get 42 in-lbs.

These are pretty small loads.

The diameter is of the typical screw driver handle pretty small...less
than 1-1/2"?

... the screwdriver / nutdriver equivalent to a torque wrench is a
torque watch,
IIRC the max torques on these devices are pretty low...like 50 in-lbs
and they have bulbous handles.

You'd be hard pressed to over torque by hand with a nut driver /
square driver if it's handle is "screw driver handle sized"

I believe in this situation the torque is so low,
either because the ground bar is aluminum or they don't want to crush
the hell out of the conductors.

cheers
Bob