Service Disconnect Grouping & Load Marking Calculator

The five requirements, with the right citations

Article 230 Part VI spreads the service-disconnect installation rules across two sections. Getting the citation right matters on an inspection: the two markings live in different sections, and the load-served marking is commonly miscited to 230.70(B) when it is actually a 230.72(A) grouping requirement.

Why the load-served marking is 230.72(A), not 230.70(B)

Two markings are easy to confuse. 230.70(B) is the identification marking: every service disconnecting means is permanently marked to identify it as a service disconnect, so anyone at the panel knows the device ahead of them is the service. 230.72(A) is a grouping rule, and it adds that where two to six disconnects are grouped, each is marked to indicate the load served (for example which unit, panel, or system it feeds). A compliant installation carries both: the service-disconnect identification from 230.70(B) and the load-served label from 230.72(A). A single service disconnect needs the 230.70(B) marking; the 230.72(A) load-served marking is about telling grouped disconnects apart.

Grouping and the water-pump exception

Grouping means the two to six disconnects are located together so the service can be shut off from one place. What qualifies as grouped (a single assembly, adjacent enclosures, or a common area) is an AHJ judgment, so place them deliberately rather than scattered around a building. 230.72(A) carries one exception: a single disconnect that supplies only a water pump also intended to provide fire protection may be located remote from the others, provided a permanent plaque or directory at the grouped disconnects points to it. This tool surfaces the exception but does not treat it as satisfying the grouping rule, because it cannot verify that the remote disconnect serves only that water pump or that the plaque is installed; a grouping failure stays noncompliant until you confirm those facts on site.

Keeping fire pump and standby disconnects remote

230.72(B) covers the extra service disconnecting means allowed by 230.2 for fire pumps, emergency systems, legally required standby systems, and optional standby systems. Those disconnects must be remote from the one to six normal service disconnects. The reason is simple: if the fire pump disconnect sat in the same group as the normal service and a responder or a fault took the whole group down, the building would lose its fire pump at the worst possible moment. Keeping it remote means a shutdown of normal service does not also drop the life-safety or standby load.

Worked examples

A small commercial building has three service disconnects, each in its own enclosure, mounted side by side on the same wall. They are grouped (230.72(A)), each is labeled as a service disconnect (230.70(B)) and with the panel it feeds (230.72(A)), and all three are in NEMA 3R enclosures outdoors (230.70(C)). With no fire pump or standby service, the installation meets 230.72 / 230.70.

The same building adds a fire pump fed from its own service disconnect. If that disconnect is bolted into the same group as the three normal disconnects, 230.72(B) is violated: it must be relocated remote from the normal service group. Move it to a separate location and the installation complies again.

Common mistakes

• Scattering the disconnects. Two to six service disconnects must be grouped, not spread around the building.
• Skipping the load-served label. Grouped disconnects each need a marking that says what they feed (230.72(A)), on top of the service-disconnect identification (230.70(B)).
• Citing the load-served marking to the wrong section. It is a 230.72(A) grouping requirement, not 230.70(B).
• Grouping the fire pump disconnect with the normal service. 230.72(B) requires it remote so a normal-service shutdown does not drop the fire pump.
• Using an indoor-rated enclosure outdoors. 230.70(C) requires each disconnect to be suitable for the prevailing conditions.

Frequently asked questions

Do service disconnects have to be grouped?

Yes, where two to six are provided (230.72(A)). A single disconnect has nothing to group. One of the two to six serving only a fire-protection water pump may be remote, with a plaque at the group pointing to it.

What marking does a service disconnect need?

Two markings: identify it as a service disconnect (230.70(B)), and, for grouped disconnects, indicate the load served (230.72(A)). Both must be permanent and legible per 110.21(B).

Where does a fire pump or standby disconnect go?

Remote from the normal service disconnects (230.72(B)), so a shutdown of normal service does not simultaneously interrupt the fire pump, emergency, or standby supply.

How many service disconnects does the NEC allow?

One to six per 230.71(B), each in its own enclosure in the 2020 NEC. The count and the minimum rating (230.79/230.80) are handled by the Service Disconnect Number and Rating Calculator; this tool checks grouping, marking, suitability, and the remote rule.

Is the load-served marking in 230.70(B) or 230.72(A)?

230.72(A). 230.70(B) only requires the service-disconnect identification. A compliant installation carries both markings.

Related calculators

• Service Disconnect Number & Rating Calculator: how many service disconnects the NEC allows and their minimum rating per 230.71, 230.79, and 230.80.
• Emergency Disconnect Requirement Calculator: the NEC 230.85 outdoor emergency disconnect and marking for one- and two-family dwellings.
• Service Size Calculator: size service-entrance conductors and the grounding electrode conductor from a known load.
• Working Space Clearance Calculator: required depth, width, and headroom in front of the service equipment per NEC 110.26(A).