Tamperproof screws on panel bus?

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Prene13

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I installed a Square D panel awhile back and the bottom 3 spaces have panel fillers that say Do not Remove and behind them on the bus where you would screw your breaker to it has tamperproof screws. Why did they do this?
 
I have seen panels where that was the situation to limit the panel to 6 breakers and list it as service equipment.
 
augie47 said:
I have seen panels where that was the situation to limit the panel to 6 breakers and list it as service equipment.
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Then, to sell an 12-space (non-service rated panel), they give it another part number, put in regular screws, and don't put the stickers on the cover.
 
Prene13 said:
I installed a Square D panel awhile back and the bottom 3 spaces have panel fillers that say Do not Remove and behind them on the bus where you would screw your breaker to it has tamperproof screws. Why did they do this?
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You are dealing with a panelboard not a Square D loadcenter (unless it is really old).

There are many reasons to prevent the use of certain spaces in a panel.
As other have mentioned one reason was to limit the number of circuits. Another reason may be to prevent the installation of additional load on bus bar connections that are all ready at their limit.

Did these screws prevent you from using the full width of the panel or just half of it?
 
Prene13 said:
I installed a Square D panel awhile back and the bottom 3 spaces have panel fillers that say Do not Remove and behind them on the bus where you would screw your breaker to it has tamperproof screws. Why did they do this?
Click to expand...

To maintain the listing of that particular panel. It could be several reasons:
  1. The hardware can be used for severa different panel configuration and rather than to develop and new piece of hardware UL allows them to use the same hardware with the modification.
  2. In the alternate configuration this is the space for a main breaker.
  3. UL did not approve the original submittal and rather than to retool, they let them use it with the restrtiction.
  4. After the original UL approval, incidents proved the inadequacy of the device so UL relisted it for a lower rating.
 
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