Quote:
Originally Posted by Howieburk
You can run low and high voltage in the same raceway if the insulation on the low voltage wiring is rated no lower than the highest voltage in that raceway.
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Kind of, in theory, but almost never in practice:
411.3(B)(3), Lighting systems 30 volts or less ("low voltage"),
600.32(A)(2), Neon secondary over 1000 volts ("high voltage"),
630.42(C), Welding cables ("lower voltage"),
640.21(B or C), Audio systems between equipment, amps, speakers ("low voltage"),
725.136(A), Class 2 and 3 ("low voltage"),
760.136(A), Power-limited fire alarm ("low voltage"),
770.133(A), Conductive optical fiber cables (NO voltage),
800.133(A)(1)(c), Communication wires and cables ("low voltage"),
810.18(B), antenna lead-in conductors, ("low voltage"),
820.133(A)(2), CATV ("low voltage"),
830.133(A)(1)(d), Network powered broadband ("low voltage").
Can't do it.
647.4(B), Sensitive Equipment ("lowish voltage", 60 volts).
Probably.
620.36 Elevators
725.48(A), Class 1 circuits ("low or high voltage") (Chapter 3 methods).
OK
So 300.3(C)(1) does allow the mixing in general, and you might make use of it sometimes, but as 90.3 shows, chapters 5, 6, and 7 modify chapters 1 through 4. That makes it rarely useable for most of us.
It is best for most of us to discard the phrases low voltage and high voltage. Over 600, 1000, or 1500 volts, depending on location and type is considered "high voltage", while 480 volts should be considered "low voltage"

, in the big picture.
Of course if you're working on a digital chip, 4 or 5 might be high, so context always matters. Using the true system designations can help us look for the actual code sections that apply.