Designing and building a good electrical power system is about more than just making sure that all of the studies turn out okay. A common construction problem that is often overlooked by engineers is working space. Working space refers to the room a qualified person has to maintain and inspect electrical equipment.
The required working space varies by voltage level. In the 2020 edition of the NEC, Table 110.26(A)(1) defines the requirements for low voltage equipment and Table 110.34(A) defines the requirements for medium voltage equipment. As voltages increase, additional working space is required. Likewise, if there are other obstacles or electrical equipment nearby, the working space needs to be increased. Between these tables, working space varies from a minimum of 3' to a maximum of 12'. Working space isn't required on side of the equipment that can't access the electrical systems inside.
3' isn't much space. Although it may be code-compliant and it should allow professionals to get into a space to do their work, you may need to increase working space beyond the minimum requirements of the NEC. Project-specific considerations and long-term maintenance needs should be evaluated prior to shrinking down projects for a minimum footprint.
There are also requirements for the practicality of the working space. It's not just about the offset distance from the equipment, but also height and width. The NEC requires that the height of the working space be at least 6' or the height of the electrical equipment, whichever is greater. The Code also requires that the width of the working space be the greater of 30" or the electrical equipment width. These kinds of requirements may seem like common sense, but they can easily be overlooked when the person building the project isn't the person putting design plans together.
Comments