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Readers help make a stronger connection to the National Electrical Code.
By Bill Dundas
My September column provided some general, installation guidelines regarding branch circuits for electric signs (see September '04, page 64, and the charts showing the maximum load capacity for various circuits). Recognizing that registered electricians aren't always the people who install and connect signs, I focused on basic precautions involved in performing this work.
I didn't intend to discuss the National Electrical Code (NEC) in this column, but a few readers were concerned that some of my statements and terminology didn't conform to the official code book. To clarify any misunderstandings, therefore, let's revisit some of these points with the expert assistance of Larry T. Cox, a registered Master Electrician and owner of Cox Electric (Seffner, FL).
Circuit ratings
The NEC dictates ratings for electric-sign branch circuits. NEC Article 600.5 (A) Branch Circuits states, "Each commercial building and tenant shall have a dedicated sign circuit, and the minimum branch circuit rating shall be 20 amperes." But the NEC provides more precise guidance based on the type of sign. Article 600.5 (B) Rating states that fluorescent or incandescent signs are restricted to 20-amp circuits. But Article 600.5(B)(2) specifies that 30-amp circuits may be used to operate neon signs.
As a sign contractor, however, I encountered several existing, fluorescent signs that were connected to either 15- or 30-amp circuits, which violates NEC rules. However, the code permits connecting more than one sign to each circuit. Cox explained, "Article 600.5 doesn't limit the number of signs on a particular circuit, as long as the total load doesn't exceed 16 amps.
For example, four fluorescent or incandescent signs, each drawing a 4-amp load, may be connected to a single, 20-amp circuit." Definitions Sign installers commonly refer to the three conductors feeding a sign as "hot," "ground" and "green" wires. But these imprecise terms don't conform to NEC definitions. Identifying primary conductors by color is undesirable, because the actual wiring connections may not agree with the color code.
The ungrounded conductor, commonly known as the "hot," typically is black, red or blue. What truly defines this conductor, however, is that it connects directly to the load side of a circuit breaker or fuse, with no connection to ground. The grounded conductor, commonly known as the "ground," connects to a grounded lug bar in the electrical panel.
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