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What's Wrong Here?

Mar 25, 2010 12:36 PM, By Brian J. McPartland, NEC Consultant

Here, we see a photo of a service panel and transfer switch at a residential occupancy. While all may appear well and good, the installer failed to provide the Code-mandated signage, which is a violation of 702.8. This is a common mistake and often overlooked rule, which is not surprising since the requirement for the required field marking is given in Art. 702, Optional Standby Systems — located in the back of the Code book.

The requirements outlined in 702.8 read as follows, "A sign shall be placed at the service-entrance equipment that indicates the type and location of on-site optional standby power sources. A sign shall not be required for unit equipment for standby illumination." The basic idea here is to alert fire-response or maintenance personnel of the existence of the generator, or other power source, and its location to help ensure that any individual who disconnects utility power is not injured or killed when the generator is started and begins back-feeding power to the service equipment, which is a "make-sense" proposition to enhance safety.

This signage is like other warning signs in that it has to contain instructions for an appropriate action. In addition to identifying the hazard, such a field marking must also include instructions with regard to the action that must be taken by the reader. In this example, additional wording such as "Keep Out" is needed. Failure to provide such an instruction has been ruled to be akin to having no sign at all. And the individual who placed the warning or caution sign has not effectively met the requirement for the Code-required field marking.

The NEC generally does not give exact wording, but instead indicates what information must be conveyed by the warning/caution sign. As noted in 702.8, the Code tells us to identify the location and type of on-site optional standby power sources. Therefore, it seems the installer should have created a label that said something like, "Disconnection of the service main will not completely de-energize the premises electrical system. The generator disconnect must also be opened." This approach will better serve to meet the Code rule and the courts’ findings regarding warning/caution signs.

It should also be noted that a sign must be provided whether the on-site power source is classified as "legally required" (Art. 701) or "optional" (Art. 702). Additionally, the last sentence eliminates the need for such a field marking for "unit equipment," which employ an alternate power source for emergency illumination.

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