Now that state law requires local governments to pare back procedural and design restrictions against the development of accessory dwelling units (“ADUs”) in California , there has been a marked increase in the number of ADU projects across the state. In Los Angeles, for example, nearly 8,000 property owners submitted ADU plans in September 2017. Despite these loosened limitations, however, it appears that many ADU applicants are running into a new hitch; namely, state regulations that mandate that new structures be built between 4’-6’ of horizontal clearance away from the aerial path of overhead power lines, in order to help prevent those power lines from falling onto the structure in the event of a break in the lines.
These power line clearance requirements have been established by the State of California in order to protect public safety and the interests of the utility companies that own the power lines. “We have to maintain these clearances for the safety of the public and for our workers,” says Dan Barnes, director of power transmission and distribution for the City of Los Angeles Department of Water and Power, because if “someone goes out and touches [a downed] line, they could be severely injured or killed.” According to the City of Los Angeles Department of City Planning, these power line clearance requirements affect “potentially one in every five to six permit applications” in Los Angeles.
In Silicon Valley, where the housing shortage has reached acute levels and efforts to address this crisis have taken on many forms, the City of Palo Alto has expected and prepared for an upswing in ADU applications. Like Los Angeles but unlike most cities, however, Palo Alto operates its own electric utility and is responsible for enforcing power line clearances and other state-mandated safety rules. As in Los Angeles, this fact poses a challenge for ADU development in Palo Alto.
In another similarity to Los Angeles, many neighborhoods in Palo Alto are served by utility lines that run across the rear of residential properties, including high-voltage transmission lines that require significantly more than the standard 4’-6’ clearances. According to a written statement issued by the City of Palo Alto Utilities, the increased clearance areas “needed for the higher voltage transmission lines would be to accommodate the larger footprint of the towers suspending the lines. These are larger than the single wooden poles found more commonly running through neighborhoods.” The total clearance needed to accommodate the footprint of such power lines is potentially larger than the typical residential property.
Because these clearance requirements are established under state law, municipal governments such as those in Los Angeles and Palo Alto seeking to encourage the development of ADUs lack the authority to waive these regulations. Due to this fact, any effort to permit these power line clearance mandates to be loosened in order to promote ADUs would require a change in state law to carry out this intent. Such legislation introduced in the last session of the California legislature, but did not pass .
In the meantime, the best advice for those people who are interested in developing an ADU, either with new construction or by converting an unused outbuilding or garage, is to pay close attention to the physical details of your property relative to power lines. Visual inspections can be useful for identifying potential clearance issues, but to be certain, it is necessary to review a survey of your property and confirm with your local building department and utility provider whether there are power line clearance requirements for your property.