This is a bug in the US library part. As best as I can tell from the script, it was probably an international/metric part that was hacked to meet some kind of US dimensions. But, not correctly.
I've posted the corrected version to the GDL Depository - you can download from the 11 Equipment > Office Equipment folder there:
http://archicad-talk.graphisoft.com/object_depository.php?
All that was changed was one line in each of the 2D and 3D scripts.
In the 2D script, the existing mul2 command was replaced with:
mul2 A*0.7722,B/.674
and in the 3D script, the existing mul was replaced with:
mul A*0.7722,B/.674,ZZYZX/1.1
(Only the scale factor affecting "A" was changed.)
Cheers,
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sequoia 15.2, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB