Atherton Municipal Code § 4.106 Site Development

4.106.5 Electric ready residential buildings. Residential buildings shall comply with Section 4.106.5.1 and Section 4.106.5.2.

4.106.5.1. New single-family and multifamily. New construction residential buildings shall comply with Section 4.106.5.1.1 and Section 4.106.5.1.2.

4.106.5.1.1. Heat pump space heater ready. Systems using a gas or propane furnace to serve individual dwelling units shall meet the requirements of 150.0(t) of Title 24, Part 6 and, in addition, include a designated exterior location for a future heat pump compressor unit with either a drain or natural drainage for condensate.

Where any pool and spa water heaters, saunas, fireplaces, outdoor cooking, or outdoor heating systems using gas or propane plumbing are installed, the construction drawings shall indicate electrical infrastructure and physical space accommodating the future installation of an electric equivalent of that system that serves the same function in the following ways, as certified by a registered design professional or licensed electrical contractor.

a) Appropriately sized conduit designed to serve a future electric appliance with the same function, including the appropriate voltage, phase, minimum amperage, and an electrical receptacle or junction box within five feet of the appliance that is accessible with no obstructions, in accordance with manufacturer requirements and the California Electrical Code. In lieu of or in addition to conduit, electrically isolated branch circuit wiring may be installed; and

b) Labeling of both ends of the unused conduit or conductors shall be with “For Future Electrical Appliance”; and

c) Reserved circuit breakers in the electrical panel for each branch circuit, appropriately labeled (e.g. “Reserved for Future Electric Fireplace”), and positioned on the opposite end of the panel supply conductor connection; and

d) Connected subpanels, main panels, and busbars, and transformers shall be sized to serve the future electric appliance. The electrical capacity requirements shall be adjusted for demand factors in accordance with the California Electric Code; and

e) Physical space for future electric appliances, including equipment footprint, shall be depicted on the construction drawings. The footprint necessary for future electric appliances may overlap with the location of currently designed combustion equipment.

Exception 1: Systems complying with the electric readiness requirements of Sections 150.0(n), 150.0(s), 150.0(t) 150.0(u), or 150.0(v) as applicable.

Exception 2: Generator systems used for emergency power generation.

Additions and alterations requiring an electrical permit shall comply with Section 4.106.5.2.1 through 4.106.5.2.5.

Exception: Where upgrades to the existing electrical panel or utility service are not proposed, electrical panel capacity shall not be required to exceed the existing utility electrical service to the building to meet compliance with Section 4.106.5.2. Capacity and overcurrent protection spaces shall be reserved to the extent allowable under the existing electrical panel capacity.

Where the electrical panel and service are upgraded, the building electrical panel and service shall be sized to meet the future electric requirements of the electric ready equipment specified in Title 24, Part 6, Sections 150.0(n) and 150.0(s) through 150.0(v). To meet this requirement the building electrical panel and utility service shall have sufficient capacity to supply full rated amperage at each electric ready appliance in accordance with the California Electric Code.

Where a branch circuit serving gas or propane range or gas wall-mounted oven appliances is altered, comply with the following requirements:

1. Install electrical components in accordance with the California Electrical Code. The electrical components shall include the following:

a. A dedicated 125 volt, 20 amp electrical receptacle that is connected to the electric panel with a 120/240 volt 3 conductor branch circuit rated to 50 amps, within 3 feet from the appliance and accessible to the appliance with no obstructions; and

• b. Both ends of the unused conductor shall be labeled with the word “spare” and be electrically isolated; and

c. A reserved single pole circuit breaker space in the electrical panel adjacent to the circuit breaker for the branch circuit in A above and labeled with the words “Future Use”; and

Where a branch circuit serving a gas or propane clothes dryer is altered, comply with the following requirements:

1. Install electrical components in accordance with the California Electrical Code. The electrical components shall include the following:

a. A dedicated 125 volt, 20 amp electrical receptacle that is connected to the electric panel with a 120/240 volt 3 conductor branch circuit rated to 30 amps, within 3 feet from the appliance and accessible to the appliance with no obstructions; and

• b. Both ends of the unused conductor shall be labeled with the word “spare” and be electrically isolated; and

c. A reserved single pole circuit breaker space in the electrical panel adjacent to the circuit breaker for the branch circuit in A above and labeled with the words “Future Use”; and

Where a utility room is altered, comply with the following requirements:

1. Where the utility room contains a gas or propane water heating appliance, comply with the following requirements:

• a. Systems using gas or propane water heaters to serve individual dwelling units shall designate a space at least 2.5 feet by 2.5 feet wide and 7 feet tall suitable for the future installation of a heat pump water heater (HPWH). All electrical components shall be installed in accordance with the California Electrical Code. The space shall include the following:

1. A dedicated 125 volt, 20 amp electrical receptacle that is connected to the electric panel with a 120/240 volt 3 conductor branch circuit rated to 30 amps, within 3 feet from the water heater and accessible to the water heater with no obstructions; and

2. Both ends of the unused conductor shall be labeled with the word “spare” and be electrically isolated; and

3. A reserved single pole circuit breaker space in the electrical panel adjacent to the circuit breaker for the branch circuit in A above and labeled with the words “Future Use”; and

4. A condensate drain that is no more than 2 inches higher than the base of the installed water heater and allows natural draining without pump assistance.

5. Where the utility room contains a gas or propane space heating appliance, install electric readiness components per Title 24, Part 6 Section 150.0(t).

Exception 1: Where the designated space specified in Section 4.106.5.2.4 would require relocation of a wall or partition that is not otherwise within the scope of the alteration, the electric readiness components per Section 4.106.5.2.4 are not required.