In Part 1, we said if your secondary-circuit wiring is under 1kV, you can use any Chapter 3 wiring method suitable for the conditions. And there were a few catches.
But what if your secondary-circuit wiring is 1kV or over? If that’s the case, you must install the conductors in one of the raceways listed in 600.32(A)(1) or in metal enclosures. And you can run them in equipment listed for use with neon secondary circuits over 1kV.
As to be expected, there are some catches:
- Conduit or tubing can contain only one conductor [600.32(A)(2)]. This contradicts the normal rule about running three current carrying conductors together to cancel out electromagnetic induction, but neon systems are different.
- The smallest conduit or tubing you can use is half-inch.
- If you use a nonmetallic conduit (flexible or rigid), you must space it at least 1.5 inches from grounded or bonded parts if it contains a conductor operating at 100Hz or less. If the conductor operates at over 100Hz, the space increases to 1.75 inches. Obviously, you can’t maintain this space to the connection to a metal enclosure or sign body because you wouldn’t be able to connect the conduit. So that is an exception to this rule.
Though not expressly prohibited for systems 1kV or less, you cannot use the metal parts of a building as a secondary return conductor or equipment grounding conductor for systems greater than 1kV [600.32(A)(5)].