I've been meaning to respond to this for a few days but couldn't get enough time. Sorry it took this long.
Blue Jean's Cable website has a number of good articles on it (besides selling cable). One discusses in-wall ratings. In the following article the ratings are discussed:
The article states that,
Originally Posted by Blue Jeans Cable
"So, if a cable isn't marked CL2 or CL3, is it suitable for in-wall installation? It may be. The NEC allows cable of a higher rating to be substituted for a lower rating, and therefore, any of the following may be used: CM, CMP, CMR, CMG, CL2R, CL3R, CL2P, CL3P, PLTC. CMX also may be used where CL2X or CL3X is required."
But, VW-1 is not listed in the above. CL2 (and the associated ratings) were developed as part of the National Electric Code (NEC) as guidelines for protecting structures and people. While the NEC code is not mandatory, many municipalities have adopted it as their requirement
making it mandatory in that municipality for all building inspections. Why was it developed? Well, in part, it was developed to prevent in-wall fires from spreading or at least reducing the spread. It was found that cables could provide a path for flames to propagate through walls. So, the guideline/requirement protects the building, the people and the buildings/people nearby.
Because you can never have enough standards, Underwriters Laboratory (UL) in the USA and the Canadian Standard Association (in Mexico, no they are in Canada) came up with their own flammability test and standards. VW-1 is their lowest residential allowed in-wall cable with restricted use.
Based on a few charts I've read this is equivalent to an NEC CL2X. In NEC 640.21(C), it states the following for in-wall use:
• (1) CL2 and CL3 are always permitted;
• (2) CL2X ("X" is a residential suffix, signifying a lower grade than plain CL2) or CL3X may be installed in raceways;
• (3) CL2X or CL3X, if under 1/4 inch in diameter, may be installed in a 1 or 2 family residential dwelling without a raceway; if nonconcealed, it may also be installed in multifamily dwellings.
So, is VW-1 acceptable for in-wall use? It may be, depending upon the usage and the dwelling. One possible problem could be that many municipaltities would not accept VW-1 as an acceptable substitution for the NEC code.
I used the following conversion chart between UL/CSA and NEC.
The bottom line is VW-1 provides some flammability protection, so Monoprice may have been at least partically correct in what they told you. Does a VW-1 cable stand as an equivalent substitution for CL-2X from a legal standpoint if something were to happen? I don't know the answer to that.Edited by alk3997 - 11/25/13 at 3:50pm