Question: will these mount to APC netshelter cabinets?
Answer: Thank you for your inquiry. This cable trough mounts into threaded holes atop the Great Lakes cabinets. However, according to the manufacturer, it should be possible to mount to an APC rack.
Please note though, mounting holes would likely need to be drilled into any non Great Lakes enclosure and additional mounting hardware may be required (nuts, washers, etc.).
The manufacturer has provided the technical drawings for this cable trough showing the dimensions and locations of mounting holes to compare with the top of your APC rack. You can find the technical drawing here:
http://files.server-rack-online.com/Great_Lakes/tct-24-drawing.pdf or on the product page.
As this use requires modifying another manufacturer's equipment, this would be a non-supported use and not 100% guaranteed to work as intended.