Steve,
The following is from the panel statement on comment 5-257 in the 2001 ROC.
PANEL STATEMENT: The panel concludes the metal-to-metal contact should be limited to surface mounted boxes only. Boxes mounted semi-flush or flush will always present the possibility of metal-to-metal contact between the box and device mounting strap
being compromised. In "old-work" installations it is not uncommon for the mounting ears for devices to be broken away from the device to allow the device to seat firmly against the 6-32 tapped hole in the box, and not the retaining ears of the "cut-in" style box. This allows the faceplates to seat firmly against the wall or surface in which the box is installed. The panel reaffirms its position in accepting the proposal adds clarity in this section and that enhanced safety is achieved.
This is a comment on proposal 5-282 that eliminated the words "or at" from this code section. You can find links to these documents
here .
Don
[This message has been edited by resqcapt19 (edited 12-17-2005).]
