I was in a lighting section of a department store last year here in New York's Chinatown and noticed that the receptacle bar (those Wiremold raceway things) that all the table lamps were plugged into was terminated in a length of AC ending with an armored heavy-duty cap (you know the ones with the grounded metal husk on them).
Needless to say it gave me the willies...especially if the end of the AC going into the plug didn't have a little "Red Devil" to protect the wires. Scrape...scrape....KA-POOF!!
Passing by some construction sites, I've seen Romex hooked up to cord caps, usually the square yellow plastic ones.
What makes me say "no" to this is common sense.
I mean...stop and think about it for a second:
The terminal screws inside a plug are small and there's not enough space to properly bend a stiff solid wire around them, so what you might have is a little stump of conductor clamped under a screw. I guess that could lead to overheating....
Also, since the insulation on AC or NM is so stiff, the cap's strain relief (if it has one) doesn't have anything to "bite" on. There's practically no "give" so the wire can also break inside the plug's housing, dance around eventually short something out in there.
Please note that these are not scientific observations, just common sense from what I've seen.
Disclaimer: I am NOT an electrician, so I tend to err on the side of caution. Also, the instruction sheets packed with some heavy-duty plugs and connectors I've used say it is to be used only with flexible cord - type X and wire gauge size Y.
[This message has been edited by SvenNYC (edited 03-26-2003).]