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Outdoor Emergency Disconnecting Means: Installing and marking this equipment for one- and two-family dwellings

By Mark C. Ode | Nov 15, 2023
STOCK.ADOBE.COM / BNP DESIGN STUDIO
The revision requiring an outdoor emergency disconnecting means for one- and two-family dwellings first occurred in the 2020 National Electrical Code in Section 230.85. It has been studied and discussed by Code-Making Panel 4 for many cycles.

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The revision requiring an outdoor emergency disconnecting means for one- and two-family dwellings first occurred in the 2020 National Electrical Code in Section 230.85. However, this is not a new issue. It has been studied and discussed by Code-Making Panel 4 for many cycles, and not just for one- and two-family services.

When I was on Panel 4 in the early 2000s, we discussed requiring an outside emergency disconnecting means on all new buildings. We determined that this requirement would be very difficult and extremely costly for large commercial and industrial facilities, and might not even be possible in many applications. Imagine a downtown high-rise where the electrical service is installed in the building’s basement because the structure occupies the entire lot without any setbacks or space for large service switchboards on the outside of the building.

Expanded requirements in 2023

Requiring this outside emergency disconnecting means for one- and two-family dwellings is much easier to implement. First responders, such as firefighters, need an outside disconnecting means to safely remove power from one- and two-family structures without having to wait for the utility to arrive before shutting down power.

The requirements in 230.85 have been expanded in the 2023 NEC. Here are some of the requirements for installing and marking the disconnecting means: 

  • The disconnecting means must be located in a readily accessible outdoor location on or within sight of the dwelling unit. 
  • The definition of “in sight from, within sight from, or within sight” in Article 100 is as follows: “Equipment that is visible and not more than 15 m (50 ft.) distant from other equipment is in sight from that other equipment.”
  • The disconnecting means can still be locked to prevent unauthorized people from gaining access. I have a 400A service with two panelboards with main circuit breakers located on the east side of my home, and both are locked to prevent vandalism and unauthorized access.
  • The disconnecting means must have a short circuit current rating (commonly called withstand rating) equal to or greater than the available fault current supplied by the utility company.

Multiple disconnecting means

If there is more than one disconnecting means, they must be grouped in one location. Based on 230.85(B), each disconnecting means must be one of the following: (1) a service disconnect, (2) a meter disconnect integral to the meter-mounting equipment not marked as suitable only for use as service equipment installed in accordance with 230.82 or (3) another listed disconnect switch or circuit breaker marked suitable for use as service equipment, but not marked as suitable only for use as service equipment, installed on the supply side of each service disconnect.

Section 230.85 states if existing “service equipment is replaced, all of the requirements of 230.85 shall apply.” There is an exception to this rule that “where only meter sockets, service entrance conductors, or related raceways and fittings are replaced, the requirements of this section shall not apply.” Since there may be additional power sources supplying the one- or two-family dwelling, such as generators, small wind turbines or solar panels, Section 230.85(D) states, “where equipment for isolation of other energy source systems is not located adjacent to the emergency disconnect required by this section, a plaque or directory identifying the location of all equipment for isolation of other energy sources must be located adjacent to the disconnecting means required by this section.” In an emergency, this plaque or directory will help the first responders determine other locations where power must also be shut off.

Proper equipment marking

Marking equipment properly is important. The outdoor emergency disconnecting means must be marked by 230.85(E)(1) as follows: A service disconnecting means must be marked “Emergency Disconnect, Service Disconnect.” A meter disconnect installed in accordance with 230.82(3) [some utilities require a meter disconnect locked with a utility company lock and accessible only by the utility] must be marked “EMERGENCY DISCONNECT, METER DISCONNECT, NOT SERVICE EQUIPMENT.” Other listed disconnect switches or circuit breakers on the supply side of each service disconnect marked suitable for use as service equipment must be marked “EMERGENCY DISCONNECT, NOT SERVICE EQUIPMENT.”

The marking is required by 230.85(E)(2) to comply with 110.21(B). They must be located on the outside front of the disconnect enclosure with red background and white text with letters at least ½ inch high. The markings will be large and colorful enough to be easily distinguished by first responders.

stock.adobe.com / BNP Design Studio

About The Author

ODE is a retired lead engineering instructor at Underwriters Laboratories and is owner of Southwest Electrical Training and Consulting. Contact him at 919.949.2576 and [email protected]

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