Ground Screws

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pfalcon

pfalcon

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Indiana
Virtually every connection in an appliance, luminaire, or toaster has gone to a decent lug or machine screw connection of some type.

Why is the ground in all these devices still a tapping style screw!?!
 
J

jim dungar

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PE (Retired) - Power Systems
pfalcon said:
Virtually every connection in an appliance, luminaire, or toaster has gone to a decent lug or machine screw connection of some type.

Why is the ground in all these devices still a tapping style screw!?!
Click to expand...

The NEC allows the use of "tapping style" screws.
 
pfalcon

pfalcon

Senior Member
Location
Indiana
jim dungar said:
The NEC allows the use of "tapping style" screws.
Click to expand...

Ah, but the question isn't whether it is legitimate. The question is WHY after going to machine screws and lugs for the regular conductors they would promote cross-threading, punctured thumbs, dropped screws, and warbling out holes for the ground screw.

The last 4 wire stove I installed had special lugs for both hots and the neutral. The hex head machine screws were simple to install and hard to drop on the floor. The ground screw is still a self-tapping screw going through a single thickness of sheet metal! They even had to add a special washer to the ground screw to increase the bonding.
 
H

hillbilly

Senior Member
The appliances are put together on a assembly line.
It's faster (and cheaper) to punch a hole when forming the steel panel and start a self tapping screw on the assembly line than it is to tap a hole.
Probably a few cents each....multiplied by millions.
That's my theory.
steve
 
H

haskindm

Senior Member
Location
Maryland
For that matter why are "ground clips" still allowed? Why ask why? Code is code. If you don't like it, submit a suggestion that it be changed during the next cycle. Otherwise, it says what it says.
 
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realolman

Senior Member
A peeve of mine is receptacles with lugs / washers for stranded wire and then a ground screw that needs a terminal on the stranded ground wire.
 
iwire

iwire

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realolman said:
A peeve of mine is receptacles with lugs / washers for stranded wire and then a ground screw that needs a terminal on the stranded ground wire.
Click to expand...

No such thing:wink: ....UL says all the screws on devices are for use with stranded wire.

That said.....I agree with you that some of the grounding screws provided on receptacles are smaller than the line conductor screws and are so small that 12 stranded is not going to stay put.
 
R

realolman

Senior Member
I'm not arguing that the use of stranded wire under a screw terminal isn't UL approved, but I don't think it should be. Hubbell (for one) makes recept with square washers under the screw heads . That seems to me to be the way to go.

Stranded wire under a screw head without a washer seems a poor connection to me.

I have nosed around the web a little and come across the thought that the ground terminal does not have the washer to discourage the use of two ground wires under the ground lug as the egc is supposed to be contiunuous even if the device is removed.
http://www.patentstorm.us/patents/6188020-description.html

i dunno
 
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