# Ground wire "dish" underneath ground screw?



## PlugsAndLights (Jan 19, 2016)

How else would you do it?
P&L


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## telsa (May 22, 2015)

BrianJayT said:


> I was trying to explain to my coworker how to use the "dish" that is underneath the ground screw. If you use, say, an Intermatic mechanical timer...under the ground screw is a small "dish". Does anyone know the proper name for this?
> I have always made a loop in the ground wire, and the wire gets placed between the "dish" and the screw. He says different. So in order to settle the argument I tried to google the right way to use it, but cant find anything, probably because I don't know the name for that piece.


Dished washer.

It's designed to go above the strands of stranded wire, that way the torquing action you apply (to screw it tight) does not directly tear at the strands.

With solid wire, there is no concern, of course.


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## telsa (May 22, 2015)

BTW, if you flip it over, the dished face will capture the strands so that they *all* remain in full contact.

The shape is intended for #12 AWG, of course.

If you're running solid, then use the washer as it comes from the factory.


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## macmikeman (Jan 23, 2007)

telsa said:


> BTW, if you flip it over, the dished face will capture the strands so that they *all* remain in full contact.
> 
> The shape is intended for #12 AWG, of course.
> 
> If you're running solid, then use the washer as it comes from the factory.



Simply wrong answer. Why would the factory ship it with the plate on backwards? It is designed to have the plate under the conductor and the screw head cinches it to the plate.


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## sbrn33 (Mar 15, 2007)

Yep, dish side down. It is made to collapse when torqued down. That is why it is opened up a tad.


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## telsa (May 22, 2015)

macmikeman said:


> Simply wrong answer. Why would the factory ship it with the plate on backwards? It is designed to have the plate under the conductor and the screw head cinches it to the plate.


1) In a world of stranded and solid -- most locations feature solid. They do fine, as is.

2) It's easier for the manufacturer, too. Robots can insert these puppies.

[ And stranded grounding wire is almost always professionally installed. The DIY crowd is down with solid Romex and UF. ]


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## macmikeman (Jan 23, 2007)

I have yet to see a single manufacturer's instructions detailing the flipping over of the dish for stranded wiring. This is my point , regardless of whether it seems to work better or not. My concern is the ''collapse'' feature that sabrina talks about. How certain can you be that the walls of the dish have sufficiently collapsed to ensure a good solid connection? By pulling on it, or do you perform certified fall of potential testing on those connections to back up the assertions that the proper way to use it with stranded conductors is to flip it over.


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## macmikeman (Jan 23, 2007)

Since we are promoting custom installation techniques , hell, the best thing is to throw away the stupid dish, and install a screw lug in that same place and install the conductor into the lug. Works great for both style of conductor.


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## Big John (May 23, 2010)

I can't for the life of me picture what y'all are describing.

Dish under a ground screw?

I've seen terminals with wire cups, but the wire didn't go under the cup, and they darn sure weren't designed to be flipped over.


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## macmikeman (Jan 23, 2007)

Dish, cup, plate, little round thing with a open place,,,,,,, on intermatic time clocks. For the ground wire.


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## emtnut (Mar 1, 2015)

BrianJayT said:


> I was trying to explain to my coworker how to use the "dish" that is underneath the ground screw. If you use, say, an Intermatic mechanical timer...under the ground screw is a small "dish". Does anyone know the proper name for this?
> I have always made a loop in the ground wire, and the wire gets placed between the "dish" and the screw. He says different. So in order to settle the argument I tried to google the right way to use it, but cant find anything, probably because I don't know the name for that piece.


I'd call that a spring loaded bevel washer.
No need to google it, you loop the ground wire ... tell him Enut said so :whistling2:


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## Semi-Ret Electrician (Nov 10, 2011)

It's hard to find an NRTL listed device rated solid or stranded 14-10 AWG that doesn't have some method of keeping the wire under the screw.

Modifying that method might be considered voiding the listing.


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## Big John (May 23, 2010)

So are we talking about this?








I googled "terminal cup washer" to find it. You put the conductor in the cup because that prevents it from spreading out of the screw head. The wire should between the screw head and the washer. 

IMO, they don't matter with solid wire, but will make a much more secure termination with stranded.


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## splatz (May 23, 2015)

Belleville washer? It's a better kind of lock washer. 

https://en.wikipedia.org/wiki/Belleville_washer 










A regular lock washer would of course tend to cut the wire.


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## drsparky (Nov 13, 2008)

I've always called it a "pressure plate", like on Square D QOs. Maybe the Square D rep can chime in.


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## PlugsAndLights (Jan 19, 2016)

splatz said:


> Belleville washer? It's a better kind of lock washer.
> 
> https://en.wikipedia.org/wiki/Belleville_washer
> 
> ...


Nope, they're different than belleville washers. Not just bevelled, actually 
cupped. It also has an area that isn't cupped for the wire to enter the cup.
Can't find a pic.. 
They're similar to the washers used on the screws holding some kitchen 
cupboards together. 
P&L

edit: Big John already posted correct pic above.


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## splatz (May 23, 2015)

Terminal washer? 

http://www.eisennet.com/f/TerminalScrews.html


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## BrianJayT (Dec 28, 2008)

Yes! Big John has it. I guess I should have use a picture...But yes, this is whats causing all the hoopla....


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## macmikeman (Jan 23, 2007)

Well you tell your co worker that the two most famous electrical guys on the internet, macmikeman, and then Big John both said the terminal washer faces open outward and let that be the end of it.


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## Kyrton (Feb 2, 2016)

Little trick I learned about stranded conductors. If you twist them in the opposite direction ( counter clockwise ) they will collapse into itself as you tighten it around a screw. It keeps it from flattening out. 

If you twist them clockwise, they tend to open up and strands start flatten out. 

Learned that one from an auto mechanic.


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## sbrn33 (Mar 15, 2007)

macmikeman said:


> Since we are promoting custom installation techniques , hell, the best thing is to throw away the stupid dish, and install a screw lug in that same place and install the conductor into the lug. Works great for both style of conductor.


Right, for solid I usually get rid of the washer, for stranded I get rid of the washer and use a sta-con.
I am mostly talking about intermatic timers since that is where I see them most.


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## 99cents (Aug 20, 2012)

Analysis paralysis.

Just screw down the ground wire and move on. Upside down? Dumb.


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## oliquir (Jan 13, 2011)

i dont bother with them i always install a crimped ring on them


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## sbrn33 (Mar 15, 2007)

oliquir said:


> i dont bother with them i always install a crimped ring on them


Even with solid? Seems goofy.


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## Semi-Ret Electrician (Nov 10, 2011)

PlugsAndLights said:


> Nope, they're different than belleville washers. Not just bevelled, actually
> cupped. It also has an area that isn't cupped for the wire to enter the cup.
> Can't find a pic..
> They're similar to the washers used on the screws holding some kitchen
> ...


Bellville washers would be a great way to make the connection, when properly torqued they would snap down. But UL RTRT does not list them..yet

Moonies used them in airports to make noise..no UL req.


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## oliquir (Jan 13, 2011)

sbrn33 said:


> Even with solid? Seems goofy.


no not on solid (i thnik i never had a situation where there was solid and those type of washer)


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