Load center terminal screws - where to buy?

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Discussion Overview

The discussion revolves around sourcing small screws used in SquareD brand load centers (breaker boxes) for securing wires to terminal strips. Participants explore various options for purchasing these screws and share insights on related wiring practices and considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant inquires about where to buy small screws for terminal strips in SquareD load centers, noting the availability of other types of screws but not the specific ones needed.
  • Another participant suggests checking the manufacturer of the breaker box or the Grainger catalog for the screws, while also cautioning about the complexities of DIY breaker box wiring.
  • A participant mentions the possibility of using screws for ground bars and suggests that if refurbishing a load center, it may be best to replace the bars entirely due to wear on the threads.
  • Concerns are raised about the positioning of wires under the screws, with one participant noting that wires often do not sit perfectly under the screw tip, potentially leading to damage.
  • There is a discussion about whether terminal strips come in versions for stranded versus solid wire, with some participants agreeing that they may have different screw designs.
  • Suggestions are made to crimp bootlace ferrules onto multi-strand wires to protect the strands before tightening the screws.
  • One participant proposes identifying the screw thread specifications and suggests various methods for acquiring spare screws, including removing screws from existing boards or purchasing short connector strips for parts.
  • A final suggestion is made to search for "set screw" online as a potential solution.

Areas of Agreement / Disagreement

Participants express a variety of views on sourcing screws and the best practices for wiring, with no clear consensus on a single solution or source for the screws. Multiple competing ideas and suggestions remain present throughout the discussion.

Contextual Notes

Participants reference specific products and practices but do not provide definitive solutions or confirm the availability of screws. There is uncertainty regarding the compatibility of screws with different wire types and terminal strip designs.

Stephen Tashi
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TL;DR
Where can a person buy the small screws that hold the wires to terminals in a SquareD brand load center (breaker box) ?
Where can a person buy the small screws that hold the wires into terminals in a SquareD brand load center (breaker box) ?

Places sell the screws that hold the panel cover on a a breaker box. They also sell the "lugs" that hold very large wires. However, what I'd like is a package of the small screws for the terminal strips that hold the 6 to 14 gauge wires.
 
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Do you want a copper split screw/bolt?
Picture : https://www.lowes.com/pd/Hillman-3-8-in-Copper-Split-Bolt/4461707
If you want the screws that hold ~8ga ... ~12ga wires to the bus try the manufacturer of the breaker box.
Check the Grainger catalog for what you need as well.

Not out of idle curiosity: If you do not know this stuff, breaker box wiring may be a poor DIY choice.
Just my opinion.
 
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Stephen Tashi said:
Summary:: Where can a person buy the small screws that hold the wires to terminals in a SquareD brand load center (breaker box) ?

Where can a person buy the small screws that hold the wires into terminals in a SquareD brand load center (breaker box) ?

Places sell the screws that hold the panel cover on a a breaker box. They also sell the "lugs" that hold very large wires. However, what I'd like is a package of the small screws for the terminal strips that hold the 6 to 14 gauge wires.
Are you talking about screws for ground bar(s) like the 15 terminal SqD part #PK15GTACP pictured below?
1576825447242.png

I've never seen screws for them sold separately, but that's not to say they aren't. If refurbishing a load center it is best to replace the bar(s) with new parts - the aluminum threads stretch a bit when tightened to spec torque - and salvage screws from the older bar.
 
Asymptotic said:
Are you talking about screws for ground bar(s) like the 15 terminal SqD part #PK15GTACP pictured below?
View attachment 254387

Yes, those are the screws I'm talking about. I find that wires under those screws often don't sit perfectly under the tip of the screw. The are captured off to one side when the screw is tightened and they nick the threads of the screw. So if you are dealing with a box that has had some rewiring, some of the screws may need to be replaced.
 
Stephen Tashi said:
I find that wires under those screws often don't sit perfectly under the tip of the screw. The are captured off to one side when the screw is tightened ...
Are you stripping off enough insulation so that the wire goes completely through the connector?
buss bar.jpg

image compliments of pinterest.com
 
dlgoff said:
Are you stripping off enough insulation so that the wire goes completely through the connector?
View attachment 254395
image compliments of pinterest.com
Yes.

The picture suggests that the exposed tip of the bare wire shoud be used to position the wire directly under the end of the screw. I find that doing this doesn't prevent the end of the screw from pushing the wire to one side once it makes contact. Flattening the end of the wire would help, but I've never seen this recommended.
 
It might be better to relieve the face of the screw so it contacts at 2 points.
 
Don't these terminal strip come in 2 versions; one for stranded wire and one for solid wire? The solid wire version might have a pointed tip on the screw, but flat tips for stranded wires.
 
  • #10
With multi-strand wire you might crimp on a bootlace ferrule before tightening the screw. That will protect the individual strands.
 
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  • #11
anorlunda said:
Don't these terminal strip come in 2 versions; one for stranded wire and one for solid wire?

They may, but my question concerns "circuit breaker boxes" for houses. They come with the terminal strips installed. Although it would interest me to know how to install wires in a new box, my question about screws is motivated by having to deal with boxes that have been installed and wired by others. When I make a minor change to some wiring (falling short of removing all the wires and installing a new terminal strip), it would be handy to have a pack of new screws.
 
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  • #12
Stephen Tashi said:
When I make a minor change to some wiring (falling short of removing all the wires and installing a new terminal strip), it would be handy to have a pack of new screws.
Have you identified the screw thread diameter, pitch and profile?

You might remove a screw from each board you work on, add it to your stock of spares.

Buy a short connector strip, then remove the screws for later use.

Go to a scrap dealer and offer to remove iron screws from terminal strips for free. That increases the scrap value of the strip.
 
  • #13
Try Googling "set screw".
 

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