230.71 Maximum Number of Disconnects.
Code Change Summary: Revised code language on allowable service configurations.
The NEC® has permitted up to six service disconnects in a single enclosure for decades. Several public inputs (code change proposals) were submitted during the 2020 NEC® code cycle voicing concerns over electrical safety hazards that exist based on the old configuration, one of which is the fact that there are always live conductors or busbars in the service enclosure even when all service disconnects are switched off.
Basically, the only way to establish an electrically safe work condition to work in the service enclosure is to have the electric utility company de-energize the service at the utility transformer.
In the 2020 NEC®, Section 230.71 was changed and now requires each service to have only one disconnecting means unless the requirements of 230.71(B) are met which provide four specific service configurations:
(1) Separate enclosures with a main service disconnect in each enclosure (see image of service B).
(2) Panelboards with a main service disconnect in each panelboard enclosure.
(3) Switchboards where there is only one service disconnect in each separate vertical section where there are barriers separating each vertical section.
(4) Service disconnects in switchgear or metering centers where each disconnect is located in a separate compartment.
Below is a preview of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the 2020 NEC® edition of NFPA 70.
2017 Code Language:
230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard or in switchgear. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault protection system
(4) Power-operable service disconnecting means
(B) Single-Pole Units. Two or three single-pole switches or breakers, capable of individual operation, shall be permitted on multiwire circuits, one pole for each ungrounded conductor, as one multipole disconnect, provided they are equipped with identified handle ties or a master handle to disconnect all conductors of the service with no more than six operations of the hand.
Informational Note: See 408.36, Exception No. 1 and Exception No. 3, for service equipment in certain panelboards, and see 430.95 for service equipment in motor control centers.
2020 Code Language:
230.71 Maximum Number of Disconnects. Each service shall have only one disconnecting means unless the requirements of 230.71(B) are met.
230.71(A) General. For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault protection system
(4) Power-operable service disconnecting means
230.71(B) Two to Six Service Disconnecting Means. Two to six service disconnects shall be permitted for each service permitted by 230.2 or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5. The two to six service disconnecting means shall be permitted to consist of a combination of any of the following:
(1) Separate enclosures with a main service disconnecting means in each enclosure
(2) Panelboards with a main service disconnecting means in each panelboard enclosure
(3) Switchboard(s) where there is only one service disconnect in each separate vertical section where there are barriers separating each vertical section
(4) Service disconnects in switchgear or metering centers where each disconnect is located in a separate compartment
Informational Note No. 1: Metering centers are addressed in UL 67, Standard for Panelboards.
Informational Note No. 2: Examples of separate enclosures with a main service disconnecting means in each enclosure include but are not limited to motor control centers, fused disconnects, circuit breaker enclosures, and transfer switches that are suitable for use as service equipment.