Appliance Disconnecting Means Calculator

Which subsection governs, by connection and rating

Article 422 Part III splits the appliance disconnect question first on how the appliance is connected, then on its rating. The branch-circuit overcurrent device, a switch or breaker, or the plug itself can be the disconnecting means depending on which box the appliance falls into.

The 300 VA and 1/8 hp thresholds

The dividing line in 422.31 is "not over 300 volt-amperes or 1/8 horsepower." A permanently connected appliance at or below those ratings lands in 422.31(A), where the branch-circuit overcurrent device alone is the disconnecting means and there is no within-sight or lockable requirement. A resistive appliance over 300 VA moves to 422.31(B); a motor-operated appliance over 1/8 hp moves to 422.31(C). Both (B) and (C) carry the same condition: the switch or circuit breaker serving as the disconnect must be within sight of the appliance, or, if it is out of sight, it must be capable of being locked open in accordance with 110.25. The split of the over-300-VA case from the over-1/8-hp case landed in 422.31(B) and 422.31(C) in the 2017 NEC, and the 2020 edition carries that structure.

Within sight, or lockable: the 110.25 detail

Within sight, per Article 100, means visible and not more than 50 ft from the appliance. When the disconnect is out of sight, 422.31(B) and (C) allow it only if it is capable of being locked open. Per 110.25, the provision for locking must be installed on or at the switch or circuit breaker and must remain in place with or without the lock. A padlock an electrician carries in a truck and clips on when leaving does not satisfy it, because the provision has to stay put when the lock is gone. A switch or breaker used as the disconnecting means must also be of the indicating type under 422.35.

Cord-and-plug appliances and the range exception

For a cord-and-plug-connected appliance, the accessible plug and receptacle is itself the disconnecting means under 422.33(A). A dishwasher or disposal on a cord to a receptacle in the sink base is the common case, provided that receptacle is accessible. Where the plug is not accessible, a disconnect has to be provided per 422.31 instead. The household electric range gets a specific allowance in 422.33(B): a plug and receptacle at the rear base of the range counts as the disconnect when it can be reached from the front by removing a drawer. In every cord-and-plug case, 422.33(C) requires the receptacle or connector to be rated at least as high as the appliance it serves.

The unit-switch allowance (422.34)

A unit switch built into the appliance, with a marked-off position that opens all ungrounded conductors, can serve as the disconnecting means Article 422 requires, but only where another disconnecting means is also present, and what counts as that other means depends on the occupancy. In a one-family dwelling the service disconnecting means counts (422.34(C)). In a two-family dwelling the other means can be inside or outside the unit (422.34(B)). In a multifamily dwelling it must be within the unit or on the same floor (422.34(A)). In other occupancies the branch-circuit switch or breaker, where readily accessible for servicing, counts (422.34(D)). A unit switch that lacks a marked-off position, or that does not open all ungrounded conductors, does not qualify.

Worked examples

A 4500 W electric water heater is permanently connected and rated 4500 VA, well over 300 VA, so 422.31(B) governs. If the panel is in the same room and in sight of the heater, the breaker is the disconnecting means. If the panel is around a corner and out of sight, the installer either adds a switch within sight of the heater or installs a permanent locking provision on the breaker handle.

A 1/2 hp garbage disposal is permanently connected and motor-operated above 1/8 hp, so 422.31(C) governs. The switch under the sink is within sight, which satisfies the rule. A plug-and-cord disposal into an accessible receptacle in the sink base would instead fall under 422.33(A), where the plug is the disconnect.

Common mistakes

• Assuming every appliance needs a local switch. At or below 300 VA or 1/8 hp, the branch breaker alone is the disconnect under 422.31(A).
• Relying on an out-of-sight breaker with no lock. Over 300 VA or 1/8 hp, an out-of-sight breaker needs a permanent 110.25 locking provision.
• Carrying the lock instead of installing it. 110.25 requires the locking provision to stay in place with or without the lock.
• Treating the range rear-base allowance as general. 422.33(B) is specific to a household electric range, not any cord-and-plug appliance.
• Counting a unit switch alone. 422.34 needs the occupancy's other disconnecting means to also be present.

Frequently asked questions

Does a water heater need a disconnect within sight?

A water heater is over 300 VA, so 422.31(B) applies: the breaker is the disconnect if it is within sight of the heater, otherwise it must be capable of being locked open per 110.25.

When can the breaker alone be the disconnect?

For a permanently connected appliance rated not over 300 VA or 1/8 hp, under 422.31(A), with no within-sight or lockable condition.

Can a plug be the disconnect?

Yes, under 422.33(A), an accessible plug and receptacle serves as the disconnect for a cord-and-plug appliance. A household range may use its rear-base plug reached by removing a drawer (422.33(B)).

Does a dishwasher unit switch count?

Only under 422.34, where it has a marked-off position opening all ungrounded conductors and the occupancy's other disconnecting means is also present.

What does within sight mean?

Per Article 100, visible and not more than 50 ft from the appliance.

Related calculators

• Motor & A/C Equipment Disconnect Location Calculator: where a motor (430.102(B)) or A/C compressor (440.14) disconnect must go: the appliance tool's motor-and-HVAC sibling.
• Emergency Disconnect Requirement Calculator: the NEC 230.85 outdoor emergency disconnect for one- and two-family dwellings.
• Overcurrent Device Location & Accessibility Calculator: where a panel or breaker may go per NEC 240.24, including the 6 ft 7 in handle-height rule.
• Snap Switch Mounting Height & Grouping Calculator: switch and breaker accessibility and the 300 V ganged-device limit per NEC 404.8.