Working space for electrical equipment

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Electrical equipment that is likely to require examination, adjustment, servicing or maintenance while energized is required to have working space with minimum dimensions complying with NFPA 70, 110.26.

This does not necessarily apply to junction and pull boxes although they are required to be accessible. These rules would apply to electrical equipment such as service equipment, panelboards and load centers, motor control centers (MCC), motor starters, motor drives (VFD), disconnects, switchboards and switchgear as well as the front of dry type transformers. This requirement is reiterated in NFPA 70, Article 440, section 440.14. It requires the disconnecting means of air conditioning equipment to also comply with 70:110.26. As if disconnects to AC equipment are not important enough to have working space. The working space must have adequate depth, width and height with access to the equipment that will allow safe operation and maintenance of the equipment while energized. Placement of signage that requires the equipment to be de-energized before performing work does not eliminate the requirement for compliant working space.

According to NFPA 70E, all electrical equipment must be considered energized until all eight steps of establishing an electrically safe working condition in accordance with section 70E:120.6 has been completed. Except for the five exceptions of 70E:110.2(B) all electrical equipment must be placed into an electrically safe working condition. This requirement is highlighted in the Informational Note at the end of 110.26(A) of the NEC.

Working depth {70:110.26(A)(1)} is dependent on the voltage to ground of the equipment and what is in front of the equipment. If there are no live or grounded parts opposite the electrical installation then this would be considered as Condition 1 and for all voltages less than 1,000 volts would require at least 3 feet. When the equipment was opposite grounded parts like block or concrete walls then this would be Condition 2. This is 3 feet for 150 volts to ground or less, 3 feet, 6 inches for 600 volts to ground or less and 4 feet for 1,000 volts to ground or less. Keep in mind this is voltage to ground and not phase-to-phase. Finally, Condition 3 is when there are live parts on both sides which will require 3 feet for 150 volts or less. 4 feet for 600 volts or less and 5 feet for 1,000 volts or less.

Working space for over 1,000 volts can be found in 70:110.34. New requirements in the 2023 NEC requires the working space to be clear and flat as practical and that open doors do not impede access and egress to less than 24 inches to the opposite door that could be opened simultaneously. In the 2017 NEC, the soft conversions of the metric dimension {90.9(C)} was converted to a hard conversion which means 3 feet once was exactly 914 mm (Soft Conversion) but in the 2017 NEC you can round down 14 mm and used the hard conversion of 900 mm instead. You have 14 mm less to play with as wiggle room when measuring the distance of working distance. You are permitted to use either the inch-pound dimensions or the metric dimensions.

The width {70:110.26(A)(2)} of working space must be at least 30 inches wide or the width of the equipment, whichever is greater. The distance can be measured from the left-side to right-side or from right-side to left-side. The 30-inch measurement does not need to be measured on the center line of the equipment.

Working space height {70:110.26(A)(3)} shall be 6 feet, 6 inches or the height of the equipment whichever is greater. This space must not have other equipment or support structures such a concrete pads that is associated with the equipment that extends more than 6 inches within the working space. For example, if a 4-inch-deep panelboard was installed with a 24” by 24” wireway installed above or below the panelboard and located within this space, it would be a violation. The remedy for this installation would be to extend the panelboard out from the wall so there is not more than 6 inches from the front of the panelboard to the front of the wireway. There are additional exceptions for batteries which must comply with 70:480.10(D). Existing residential locations with service equipment or panelboards not exceeding 200 amps. And finally, it allows the meter installed in meter sockets to extend more than 6 inches into this space.

Access {70:110.26(A)(4)} to the electrical equipment is required when the equipment is located above drop ceilings or within crawl spaces like attics. This section was added to the 2017 NEC which basically brings clarification to installations that we are already doing. It requires the drop ceiling opening to not be less than 22” by 22” and the crawl space opening to not be less than 22” by 30”. In all cases the working space depth and width must comply with 110.26(A)(1) and (A)(2). The doors must also be able to open up to at least 90 degrees. Installations of low voltage equipment may be reduced by special permission for live parts not operating more than 30 volts rms, 42 volts peak, or 60 volts dc.

The NEC also requires this working space to be kept clear and not to be used for storage. Often, the owners of the occupancy may highlight or outline this space by applying marking tape or paint on the floor in accordance with the dimensions of 70:110.26. This is supported with signage that prohibits storage within this space.

Entrance to and egress from electrical equipment must be provided based on the variables like the width of the equipment or the ampere rating of the equipment. For equipment greater than 6 feet wide or 1200 amps or more shall be with provided with an entrance and egress to working space of at least 24 inches wide and 6 feet, 6 inches at each end of this space unless other conditions permit one.

Illumination must be provided, and the lighting must not be controlled by automatic means.

All service equipment, switchboards, switchgear, panelboards and motor control centers must be located in dedicated spaces and protected from damage. This equipment also requires dedicated space that is the width and the depth of the equipment from the floor up to the height of 6 feet above the equipment or the structural ceiling, whichever is lower to allow for circuits to be installed or removed after the original installation. No other systems are permitted within this area except for fire sprinkler systems or ceiling tiles as part of a listed ceiling assembly. If foreign systems are located within this dedicated space then protection from leaks or condensation must be provided.

The Code permits the use of locked doors and locked electrical equipment to comply with 70:240.24 which requires overcurrent devices to be readily accessible.

Without the adequate working space and access to electrical equipment, servicing, testing or maintenance of energized equipment could be hazardous. Working on energized equipment already has inherent risks. Why impose additional risks with a reduction of the required working space? A little foresight and planning can prevent many of the violations.  With new rules for open doors in the 2023 NEC, preplanning must be a priority, or a violation will be encountered which could be very costly to correct. Adequate working space helps permit access to the equipment but also allows for a safe and rapid exit if an arc flash event would occur. Working space that is compliant with the NEC will permit safe operation and maintenance of the equipment. Finally, you might also need to follow other NFPA standards, including 70B for Standards for Electrical Equipment Maintenance, as well as manufacturer’s installation instructions.