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Electric Signs and Lighting, Part 5

Electric Signs and Lighting, Part 5In many Chapter Six articles, grounding and bonding requirements [600.7] are near the end (almost as an afterthought). But in Article 600, they’re close to the beginning. And they are extensive, relative to the size of the article.

It makes sense that these requirements have such emphasis, considering the extra danger that sign locations typically present for maintenance and repair.

It’s important to understand that the NEC is still in transition in its use of “grounding” and “bonding.” The terms mean, respectively, “connecting to the earth” and “making an electrical path using a reliable conductor” [Article 100].

Generally, you ground at the service (or separately derived source) but not on the load side. Outdoor loads may additionally have supplemental ground connections, but not in place of where bonding connections are required.

Electric signs and lighting are loads, not sources, so you don’t ground them (except supplementally). You bond them. Nonetheless, Section 600.7 is divided into two subsections, A and B, which respectively cover “grounding” and “bonding.”

Actually, 600.7(A) is presenting equipment bonding requirements, while 600.7(B) is presenting the requirements for bonding of metallic parts. This distinction makes sense, but not if you lose track of the fact that you don’t run a copper wire from your sign to a ground rod and consider the sign properly “grounded.” This arrangement leaves a potentially lethal shock hazard on that sign.

We’ll examine the equipment bonding requirements, next.

« Part 4 |  Part 6 » | Source: Mark Lamendola | Mindconnection