This section provides requirements for all disconnecting means, devices, or group of devices, or other means by which the conductors of a circuit can be disconnected from their source of supply.
(A) General
A disconnecting means has to be marked, legibly, and in a durable manner to withstand the environment, to indicate its purpose. If the disconnecting means is in such a location that its purpose is evident, it is not required to be marked to indicate its purpose. When in other than one- or two-family dwellings, the source that supplies the disconnecting means must be identified with regard to its location. Again this marking is not required if the source is evident merely because of location and proximity.
(B) Engineered Series Combination Systems
A series combination system is the ability of two overcurrent protective devices working together to stop the flow of current when the second device located downstream of the first device is applied where the available fault current exceeds its interrupting rating.
This first level subdivision addresses when the series rating system is engineered and not listed and labeled as such. The requirement here is that the engineering must meet the requirements of 240.86(A) and must be legibly marked in the field as directed by the engineer. The system must be shown to have an engineered series combination rated that exceeds the available fault current at that equipment. 110.22(B) provides language for the marking to be applied in this case.
(C) Tested Series Combination Systems
A series combination system is the ability of two overcurrent protective devices working together to stop the flow of current when the second device located downstream of the first device is applied where the available fault current exceeds its interrupting rating.
This first level subdivision addresses when a tested series combination system is available that shows the series combination system rating is greater than the available fault current at the location. This section has equipment enclosures labeling requirements for compliance demonstrating the series combination system rating based on test results. Listed solutions will provide the documentation necessary to meet this requirement.
Eaton’s series ratings documentation and information is available here.
110.22(C) provides language for the marking to be applied in this case.
Relative terms related to this requirement include the following:
Disconnecting Means
240.86 Series Ratings
430.109 Type
NFPA 70-2023 Changes
The words “and location” were added to (A) General Requirements in regard to marking of the disconnect means. This does not have to be marked if the disconnecting means is located and arranged so the identification and location of the circuit source is evident. Location of source circuit will have to be marked on the disconnecting means for other than one and two family dwelling units. This is quite significant. For example, every luminaire disconnect will be required to have a marking of location of the source. It’s important to understand the definition of disconnecting means to gather the significance of this change.This change was implemented for electrical worker safety to clearly identify the source circuit for the disconnecting means being worked on. Location is important to help identify where the source is physically located so as to facilitate the abilty to establish an electrically safe work condition.