Table 110.34, "Working Space and Clearances," applies to equipment operating at 600 volts, nominal, or less. The specific equipment types mentioned in the table heading are: Switchboards Switchgear Panelboards Motor Control Centers (MCCs) Disconnecting MeansTransformers are not explicitly listed in the heading of Table 110.34.

However, the General requirements of 110.26 and 110.34 are that all the equipment listed have to have the proper working space.

Ultimately, the application of Table 110.34 to transformers depends on several factors


Voltage

The table specifically states "600 Volts, Nominal, or Less." If the transformer operates at or below this voltage, the working space requirements of 110.34 are relevant.
2.

Accessibility for Maintenance

If the transformer requires routine maintenance, adjustments, or examinations while energized or potentially energized, then adequate working space is required for personnel safety. This is a critical consideration, regardless of whether the transformer is specifically listed in the table heading.3.

Code Interpretation

The local Authority Having Jurisdiction (AHJ) has the final say in interpreting the NEC. If the AHJ considers a transformer to be similar enough to the equipment types listed in the table heading (especially regarding the need for working space for safe operation and maintenance), they may require compliance with Table 110.34.

In summary

While transformers are not explicitly listed in the heading of Table 110.34,

transformers operating at 600 volts or less and require work to be performed while energized or potentially energized will require working space per 110.26 and 110.
34.* It's always best to consult with the AHJ for clarification on how these requirements are applied in your specific jurisdiction.

Recommendation: To avoid any potential issues, it is highly recommended to design and install transformers with adequate working space that meets or exceeds the dimensions in Table 110.34 when it is reasonable to do so. This proactive approach promotes safety and ensures compliance with the intent of the code, even if a strict interpretation might suggest otherwise. Flag for review