The National Electrical Code includes many long-standing, historical requirements that are still applied to today’s installations. From the beginning of electricity use, the need for disconnecting electric service to the premises wiring was essential. The requirement for a single service (main) disconnect was adequate early on, but as capacity needs increased, the service disconnecting means was allowed as either a single disconnect or multiple (two to six) disconnects. If multiple disconnects were installed, they were required to be grouped in the same location. The idea behind the grouping rule was that the electrical power could be effectively disconnected by either a single throw of the hand or by not more than six. This is where the grouping requirement is important.

The NEC has many clear and concise requirements. There are also practical exceptions to many general requirements. Throughout the code, there are also some “gray areas” that require practical expertise and experience along with exercising good judgment for optimal results and attaining compliance. A “good code” is practical, easy to read (and understand) and enforceable. This article addresses the gray areas associated with the service disconnecting means location(s) and the multiple service disconnecting means grouping requirement(s). Let’s look at some definitions first.

Definitions matter

“Disconnecting means” is defined as not one, but could be multiple, means of disconnects, as addressed in Part VI of Article 230, and more specifically, sections 230.70 (General), 230.71 (Maximum Number of Disconnects) and 230.72 (Grouping of Disconnects). 

As we review the general service disconnecting means location requirements in 230.70(A)(1), there are specific objectives. The first is that the service disconnecting means be readily accessible. This is not a gray area, as this term is clearly defined in Article 100 as capable of being reached for quick operation without resorting to using ladders or climbing over obstacles, etc. 

The second part of the location rule uses the word “nearest,” which is a gray area and a word that can make a requirement vague or unenforceable. It is not recommended for use by the NEC Style Manual. The text reads “the service disconnecting means shall be installed at a readily accessible location either outside the building or structure or inside nearest the point of entrance of the service conductors.” Notice there is no distance provided, and for good reason. Each service (large or small) must follow the same requirement. For a small service, say 100A, single-phase, 240/120V, the distance from the point of entrance to the disconnecting means can be relatively short, whereas for a larger service, say a 4,000A, three-phase, four-wire, 480Y/277V, the distance from the point of entrance to the service disconnecting means could be much longer.

The idea behind this requirement is to limit the distance of unprotected service conductors routed inside the building or structure. The code recognizes that a distance is needed but does not provide the limiting distance. Each installation will warrant its own practical allowance to achieve substantial code compliance and meet the rule’s intent. 

Another gray area

The other gray area is where two to six disconnects are permitted as the service disconnecting means, but they all must be grouped in the same location. It is important to recognize that there is no maximum distance between the grouped service disconnects. While the service disconnecting means as a whole is required to be readily accessible, there are no requirements that the grouped service disconnects be arranged so they are readily accessible from each other, nor do they have to be installed within sight from one another. These are both probably really good design considerations, but the NEC minimum does not require them. 

So, from a practical standpoint, when applying these rules in the field, it is a good idea to remember the original objectives of the two to six grouping requirement to remove the power at the service either with a single throw of the hand, or with up to six. It is ideal if all six disconnects are in the same enclosure (as allowed by exception) or in separate enclosures and clearly identified as grouped service disconnects, such as one of six, two of six, three of six, etc. Where the service disconnects are not installed within sight from one another, it would be good to direct the operator to each service disconnect in the group by way of clear identification labeling for those who must operate them for interruption of service, whatever the reason.