What are you guys considering low voltage?  Some electricians would say 12-24 volts but utility linemand would say 277, 480 Volts.  Do you mean less than 240 v?
Thanks

What is A Low Voltage Circuit?
he NEC does not consistently define low voltages. In 110.26(A)(1)(b), voltages of not greater than 30 volts ac rms and 60 volts dc are the dividing line. Article 720 is titled "Circuits and Equipment Operating at less than 50 volts." Article 725 uses tables which list voltages from 0 through 150 volts ac and dc. Other Sections of the Code are divided based on whether or not the voltage is less than or equal to 600 volts or over 600 volts. Still other sections use 150 and 250 volts as the dividing line. "Low voltage circuit" just like "low voltage work" are slang terms that do not have precise definitions but are commonly used to describe what most electricians think of as work with voltages under 50 volts and using No. 16, No. 18 and smaller wire sizes.
Note: Most control work is in Section 15 of job bid packages and since Section 15 is the mechanical section, control work is often performed by employees of the mechanical contractor and not by electricians employed by the electrical contractor.

In reference to the catagory you're asking your question under, low voltage is a variable (depending on application and element length) from 14 - 60 VAC. Zmesh elements run from about 16 and 30 VAC and Tuff Cable elements run from 14 to 60 VAC.