NEC 700-702 — Emergency & Standby Systems (Washington Journeyman)

Learning Objectives

Distinguish emergency (Article 700), legally required standby (Article 701), and optional standby (Article 702) systems by scope and obligation.

Apply the time limits that divide the articles: 10 seconds for emergency and 60 seconds for legally required standby.

Size and rate alternate sources under 700.5, 701.5, and 702.4, including load management, energy management systems, and PCS settings.

Specify transfer equipment correctly: automatic or interlocked, listed and marked, with bypass, isolation, and short-circuit current rating documentation.

Identify the signals, signs, and records each article requires, and apply the commissioning and testing rules of 700.4 and 701.4.

1.1 Emergency Systems — Article 700

Article 700 applies to the electrical safety of the installation, operation, and servicing of emergency systems: circuits and equipment that supply, distribute, and control electricity for illumination, power, or both to required facilities when the normal supply is interrupted (700.1). Covered systems consist only of those permanently installed in their entirety, including the power source.

Under 700.12, emergency lighting, emergency power, or both shall be available within the time required for the application but not to exceed 10 seconds. Under 700.5(B) the system shall have adequate capacity in accordance with Article 120 Parts I through IV or another approved method, sufficient for the rapid load changes and transient power and energy requirements associated with any expected loads, and 700.5(A) requires equipment suitable for the available fault current at its terminals.

Emergency loads stay separate from everything else. Section 700.5(C) lets the alternate source supply emergency, legally required standby, and optional standby loads where it has adequate capacity or where load management — including automatic selective load pickup and load shedding — ensures adequate power, in a fixed priority: (1) emergency circuits, (2) legally required standby circuits, (3) optional standby circuits. From the other direction, 700.6(D) states that transfer equipment shall supply only emergency loads, and reconditioned transfer switches shall not be installed in any of the three articles (700.3, 701.3, 702.3).

1.2 Legally Required Standby Systems — Article 701

Article 701 applies to the electrical safety of the installation, operation, and servicing of legally required standby systems: circuits and equipment that supply, distribute, and control electricity to required facilities for illumination or power, or both, when the normal supply is interrupted (701.1). Covered systems consist only of those permanently installed in their entirety, including the power source, and the informational notes list loads such as heating and refrigeration, communications, ventilation and smoke removal, and sewage disposal that could create hazards or hamper rescue or firefighting operations when stopped. Legally required standby power must be available within the time required for the application but not to exceed 60 seconds (701.12), against the 10 seconds of Article 700.

Capacity and rating (701.5). Equipment must be suitable for the available fault current at its terminals (701.5(A)). The system must have adequate capacity in accordance with Article 120 Parts I through IV or another approved method, sufficient for the rapid load changes and transient power and energy requirements associated with any expected loads (701.5(B)). Section 701.5(C) permits the alternate source to supply legally required standby and optional standby loads where it has adequate capacity or where load management, including automatic selective load pickup and load shedding, ensures adequate power to the legally required standby circuits.

Parallel operation (701.5(D)). Parallel operation must comply with Article 705 Part I or Part II. Under 701.5(D)(1) the alternate source may operate in parallel with the normal source where the capacity required to supply the legally required standby load is maintained at all times, and any operating condition that results in less than the required source capacity shall initiate a legally required standby source malfunction signal in accordance with 701.7(A); parallel operation is also permitted for satisfying the test requirements of 701.4(B). Under 701.5(D)(2), standby sources may operate in parallel where the necessary equipment to establish and maintain a synchronous condition is provided.

Transfer equipment (701.6). Transfer equipment must be automatic, listed, and marked for emergency system or legally required standby use, and designed and installed to prevent the inadvertent interconnection of normal and alternate sources in any operation; equipment permitting parallel operation must meet 705.2, and meter-mounted transfer switches are not permitted for legally required system use. Automatic transfer switches must be electrically operated and mechanically held. Where loads are supplied by a single feeder, the system may include bypass and isolation equipment per 701.4(C): a means to bypass the transfer equipment while maintaining continuity of power with inadvertent parallel operation prevented, a means to isolate it from all supply side and load side sources, and active supervision by a qualified person when manual or nonautomatic bypass equipment is used while the primary automatic transfer equipment is disabled. The short-circuit current rating of the transfer equipment, based on the specific OCPD type and settings protecting it, shall be field marked on the exterior.

Signals (701.7). Audible and visual signal devices shall be provided, where practicable, for (A) malfunction of the standby source, (B) the standby source carrying load, (C) battery charging malfunction on a battery required for source readiness, including the prime mover starting battery, and (D) ground fault. The ground-fault rule covers solidly grounded wye legally required standby systems of more than 150 volts to ground with circuit-protective devices rated 1000 amperes or more: the sensor must be located at, or ahead of, the main system disconnecting means for the legally required standby source, and the maximum setting of the signal devices shall be for a ground-fault current of 1200 amperes.

1.3 Optional Standby Systems — Article 702

Article 702 applies to the installation and operation of optional standby systems (702.1). Covered systems include those permanently installed in their entirety, including prime movers, and those arranged for connection to a premises wiring system from a portable alternate power supply. The informational note describes the typical duty: industrial and commercial buildings, farms, and residences, serving loads such as heating and refrigeration, data processing and communications systems, and industrial processes that, when stopped during any power outage, could cause discomfort, serious interruption of the process, or damage to the product or process. No life-safety mandate is imposed, so Article 702 asks least of the installer. Reconditioned transfer switches shall not be installed (702.3) — the prohibition is absolute and not conditioned on listing, dwelling-unit use, or AHJ approval.

Capacity and rating (702.4). The rule branches on how the load is connected.

Manual and nonautomatic load connection — 702.4(A)(1). The system must have adequate capacity and rating for the supply of all equipment intended to be operated at one time, and the user is permitted to select the load connected; the full connected load of the premises is not the criterion.

Automatic load connection — 702.4(A)(2). The system must comply with 702.4(A)(2)(a) or 702.4(A)(2)(b) in accordance with Article 120 Parts I through IV or another approved method. Under (a), full load, the standby source must supply the full load that is automatically connected. Under (b), energy management system (EMS), the standby source capacity using an EMS must automatically manage the connected load and comply with one of two options: a system employed in accordance with 130.30, or a system with a PCS control setting in accordance with 130.70.

Multimode inverter-based systems in one- and two-family dwellings — 702.4(A)(2)(c). Systems listed as a PCS for overload control must have a minimum capacity equal to the PCS control setting of the standby source in accordance with Article 130 Part II, and no less than the load posed by the largest single utilization equipment connected to the system; after an overload shutdown, reconnection may only be performed nonautomatically.

Interconnection or transfer equipment (702.5). Paragraph (A) requires interconnection, an interlocking device, or transfer equipment for all standby systems subject to the article, suitable for the intended use and listed, designed, and installed so as to prevent the inadvertent interconnection of all sources of supply in any operation; the exception permits temporary connection of a portable alternate power source without transfer equipment where conditions of servicing and supervision ensure that only qualified persons service the installation and where the normal supply is physically isolated by a lockable disconnecting means or by disconnection of the normal supply conductors. Paragraph (B) requires transfer switches installed between the utility meter and the meter enclosure to be listed meter-mounted transfer switches, and approved. Paragraph (C) requires that, in other than dwelling units, the short-circuit current rating of the transfer equipment be field marked on the exterior. Paragraph (D) requires systems installed to permit parallel operation with the normal source to also meet Article 705 Part I or Part II.

Signals and signs (702.6, 702.7). Section 702.6 requires audible and visual signal devices, where practicable, for two purposes only — malfunction of the optional standby source (702.6(A)) and the source carrying load (702.6(B)) — and exempts portable standby power sources. Section 702.7 requires permanent placards, labels, or directories locating each permanently installed on-site optional standby power source disconnect, installed at the disconnecting means required in 225.41 and 230.70(A)(2) for one- and two-family dwellings and at the service equipment for other occupancies.

1.4 Transfer Equipment Across the Three Articles

Transfer equipment is the highest-yield comparison in the chapter, because the three articles use nearly identical language with deliberate differences (700.6, 701.6, 702.5).

Article	Required switching	Listing and marking	Documentation
700 Emergency	Automatic; automatic transfer switches electrically operated and mechanically held; supplies only emergency loads	Listed and marked for emergency use; meter-mounted transfer switches not permitted	Short-circuit current rating field marked on the exterior
701 Legally required standby	Automatic; automatic transfer switches electrically operated and mechanically held	Listed and marked for emergency system or legally required standby use; meter-mounted transfer switches not permitted	Short-circuit current rating field marked on the exterior, per 701.6(D)
702 Optional standby	Interconnection, interlocking device, or transfer equipment; manual and nonautomatic equipment uses human intervention; a portable source may be temporarily connected without transfer equipment under the 702.5(A) exception	Suitable for the intended use and listed; a switch between the utility meter and the meter enclosure must be a listed meter-mounted transfer switch and approved	In other than dwelling units, the short-circuit current rating field marked on the exterior, per 702.5(C)

Signal practice separates as well: 700.7 calls for audible, visual, and facility or network remote annunciation devices, 701.7 for audible and visual signal devices, and 702.6 for malfunction and carrying load only, with portable sources exempt. Bypass and isolation under 701.6(C) needs no occupancy restriction; 700.6 limits the same provision to occupancies listed in 700.10(D)(1).

1.5 Sources of Power, Duration, and Timing

Article 700 fixes the emergency time at 10 seconds. Article 701 allows 60 seconds (701.12) but imposes its own duration floor: under 701.12(B) the alternate power source must be of suitable rating and capacity to supply and maintain the total load for the duration determined by the system design, and in no case shall the duration be less than 2 hours of system operation. Supporting rules run from (B)(1) to (B)(5): an on-site fuel supply sufficient for not less than 2 hours of operation; fuel transfer pumps connected to the system; storage batteries and UPS used to supply standby illumination of suitable rating and capacity to supply and maintain the total load for a minimum period of 1 1/2 hours without the voltage applied to the load falling below 87 1/2 percent of nominal voltage, with automotive-type batteries prohibited and an automatic battery charging means provided; and automatic transfer between dual fuel sources.

Generator sets are covered by 701.12(C). For a prime mover-driven set sized in accordance with 701.5, means must be provided for automatically starting the prime mover on failure of the normal power source and for automatic transfer and operation of all required circuits, and a time-delay feature permitting a 15-minute setting shall be provided to avoid retransfer in case of short-time reestablishment of the normal source. Stored-energy power supply systems under 701.12(D) must be of one or more listed types, such as uninterruptible power supply, fuel cell system, energy storage system, or storage battery.

One 2026 numbering note: capacity for all three articles uses Article 120 Parts I through IV, where branch-circuit, feeder, and service load calculations now sit; study material citing Article 220 does not match the 2026 text.

1.6 Commissioning, Testing, Servicing, and Records

Articles 700 and 701 share a four-part maintenance regime tested by paragraph letter. Under 700.4(A) the authority having jurisdiction conducts or witnesses the commissioning of the completed system upon installation and periodically afterward; under 701.4(A) the AHJ conducts or witnesses commissioning upon installation. Under 700.4(B) and 701.4(B) systems are tested periodically on an approved schedule to ensure they are maintained in proper operating condition. Servicing sits in 700.4(C) and 701.4(C): equipment is maintained in accordance with manufacturer instructions and industry standards. Record keeping sits in 700.4(D) and 701.4(D): a written or digital record is kept of the tests and maintenance or servicing and made available to those authorized to design, install, inspect, maintain, and operate the system.

Testing under load is the requirement most often misread. Section 700.4(E) requires means for testing all emergency lighting and power systems during maximum anticipated load conditions, and 701.4(E) requires means for testing legally required standby systems during maximum anticipated load conditions. Neither section substitutes a percentage of rated load, conditions testing on a utility outage, or permits a no-load test.

1.7 Temporary and Portable Alternate Sources

Section 700.4(F) answers a practical question: what happens when the emergency system relies on a single alternate source of power that will be disabled for servicing? The system must include permanent switching means to connect a portable or temporary alternate source of power available for the duration of the servicing. Connection to the portable or temporary source shall not require modification of the permanent system wiring, and transfer of power between the normal source and the emergency source follows 700.12. The connection point must be marked with the phase rotation and system bonding requirements. The permanent connection point for the temporary generator must be located outdoors and shall not have cables from the connection point to the temporary generator routed through exterior windows, doors, or similar openings. A permanent label must be field applied at the connection point identifying the system voltage, maximum amperage, short-circuit current rating of the load side of equipment supplied, and ungrounded conductor identification in accordance with 210.5.

Code Navigation

Topic	NEC Section	What it covers
Scope of the three tiers	700.1, 701.1, 702.1	Emergency, legally required standby, and optional standby systems; permanently installed including the source, except that Article 702 also reaches portable connections
Commissioning, testing, servicing, records	700.4, 701.4	AHJ-witnessed commissioning; periodic testing on an approved schedule; servicing per manufacturer instructions; written or digital records; testing at maximum anticipated load
Capacity and rating	700.5, 701.5, 702.4	Available fault current at the terminals; capacity per Article 120 Parts I through IV for rapid load changes and transient power and energy requirements; automatic selective load pickup and load shedding; EMS and PCS options under 130.30 and 130.70
Parallel operation	700.5(D), 701.5(D), 702.5(D)	Article 705 Part I or Part II where required capacity is maintained at all times; loss of capacity initiates a malfunction signal under 700.7(A) or 701.7(A); synchronous condition equipment for parallel sources
Transfer equipment	700.6, 701.6, 702.5	Automatic, listed, marked equipment preventing inadvertent interconnection; automatic transfer switches electrically operated and mechanically held; meter-mounted switches prohibited for Articles 700 and 701; bypass and isolation; exterior short-circuit current rating marking
Signals	700.7, 701.7, 702.6	Malfunction, carrying load, battery charging malfunction, and ground fault under Articles 700 and 701; malfunction and carrying load only under Article 702, which exempts portable sources; 1200-ampere maximum setting
Signs and labeling	700.8, 701.8, 702.7, 210.5	Service-entrance signs naming each source; grounding warning labels per 110.21(B); placards or directories at 225.41 and 230.70(A)(2); ungrounded conductor identification per 210.5
Sources of power and duration	700.12, 701.12	10 seconds for emergency, 60 seconds for legally required standby; 2-hour minimum duration and 1 1/2 hours at 87 1/2 percent of nominal voltage for batteries and UPS; 15-minute retransfer delay

Common Exam Traps

Confusing the 10-second and 60-second rules. Emergency lighting and power must be available within the time required for the application but not to exceed 10 seconds (700.12); legally required standby power has up to 60 seconds (701.12), and Article 702 sets no availability limit.

Reversing the 700.5(C) priority list. With mixed loads the order is emergency circuits, then legally required standby circuits, then optional standby circuits, and load management must include automatic selective load pickup and load shedding.

Thinking parallel operation is forbidden. Under 701.5(D)(1) the alternate source may operate in parallel with the normal source where the capacity required to supply the legally required standby load is maintained at all times, and 701.5(D)(2) permits parallel sources where necessary equipment to establish and maintain a synchronous condition is provided.

Losing track of the 1200-ampere ground-fault setting. In 701.7(D), 1000 amperes is the circuit-protective device rating that triggers the rule and 150 volts is the voltage-to-ground threshold; the maximum setting of the signal devices is a ground-fault current of 1200 amperes.

Expecting the full load from a manual-connection optional standby system. Under 702.4(A)(1) the system needs adequate capacity and rating for all equipment intended to be operated at one time, and the user may select the load connected; the full-load rule belongs to 702.4(A)(2)(a).

Using any energy management system to shrink the standby source. Section 702.4(A)(2)(b) allows only a system employed in accordance with 130.30 or a system with a PCS control setting in accordance with 130.70, and 702.4(A)(2)(c) adds the PCS control setting floor plus the largest single utilization equipment load for one- and two-family dwellings.

Allowing a meter-mounted transfer switch everywhere. It is not permitted for emergency system use (700.6(A)) or legally required system use (701.6(A)); in Article 702 a switch between the utility meter and the meter enclosure must be a listed meter-mounted transfer switch and approved.

Forgetting which paragraphs hold servicing and records. Sections 700.4(C) and 701.4(C) cover servicing, while 700.4(D) and 701.4(D) hold the written or digital record requirement and 700.4(E) and 701.4(E) require testing at maximum anticipated load.

Practical Field Points

Mark the article. An emergency transfer switch must be marked for emergency use, a legally required standby switch for emergency system or legally required standby use, and only an optional standby switch may be a listed meter-mounted type installed between the meter and the meter enclosure.

Document the short-circuit current rating. Field mark it on the transfer equipment exterior, based on the specific OCPD type and settings protecting it, remembering that Article 702 requires it only in other than dwelling units.

Ground-fault signalling. Set the sensor at or ahead of the main system disconnecting means for the standby source and the signal for a ground-fault current of 1200 amperes on a solidly grounded wye system above 150 volts to ground protected at 1000 amperes or more, with the course of action posted at or near the sensor.

Plan the temporary source. The connection point must be outdoors, cables may not pass through exterior windows or doors, the connection must not require modifying permanent wiring, and the label must state system voltage, maximum amperage, load-side short-circuit current rating, and ungrounded conductor identification.

Check inverter systems against the PCS setting. For a one- and two-family dwelling with a multimode inverter listed as a PCS, verify capacity against the PCS control setting of the standby source under Article 130 Part II and the largest single utilization equipment load, and confirm that reconnection after an overload shutdown is nonautomatic.

Summary

Articles 700, 701, and 702 cover the three tiers of alternate power and differ mainly in how much the code demands. Article 700 governs emergency systems supplying illumination, power, or both to required facilities, permanently installed including the power source, available within the time required for the application but not to exceed 10 seconds, with transfer equipment that is automatic, listed, marked for emergency use, and supplies emergency loads only. Article 701 governs legally required standby systems, also permanently installed including the power source, available within 60 seconds, suitable for the available fault current at their terminals, and sized under Article 120 Parts I through IV for rapid load changes and transient power and energy requirements, with an on-site fuel supply and a supply duration of not less than 2 hours, and with batteries or UPS for standby illumination sized for 1 1/2 hours without falling below 87 1/2 percent of nominal voltage. Article 702 governs optional standby systems, including portable sources, where manual load connection requires capacity for all equipment operated at one time, automatic connection follows 702.4(A)(2)(a) or (b), and reconditioned transfer switches remain prohibited. All three articles require the short-circuit current rating marked on the transfer equipment and signals for malfunction and carrying load, while Articles 700 and 701 add battery charging malfunction and ground-fault signals.

NEC 700-702 — Emergency & Standby Systems (Washington)