## 8.3 Separation of Electrical Circuits for Electrical Energy Monitoring

§130.5(b)

The Separation of Electrical Circuits requirement sets up a backbone for monitoring the specific contributions of separate loads to the overall energy use of the building. By designing the electrical distribution system with separation of electrical loads in mind, energy monitoring can be readily set up and implemented without significant physical changes to the electrical installations. The goal is to be able to monitor the electrical energy usage of each load type specified in Table 130.5-B of the Energy Standards. Building owners, facility management, and others can make use of such energy usage information to better understand how much energy has been used by each building system during a certain period. Further analysis of such energy information can help facilitate energy efficiency and related measures to improve building energy performance for building owners and operators.

For the 2019 Standards, healthcare facilities are exempted from the requirement of Section 130.5(b), Separation of Electrical Circuits for Electrical Energy Monitoring. Healthcare facilities overseen by the California Office of Statewide Health Planning and Development (OSHPD) are brought into the scope of Title 24 Part 6 for the first time, and this exemption avoids potentially conflicting requirements for healthcare facilities.

Example 8-5

Question:

My new nonresidential building is served by a single panel with a service less than 50 kVA.

What is the required separation of electrical circuit requirement for this building?

Answer:

Since the service is smaller than 50 kVA, renewable power sources and electric vehicle charging stations shall be separated from other electrical load types and from each other, in accordance with the “Electrical Service rated 50kVA or less” column of Table 130.5-B and §130.5(b).

The renewable power source shall be separated by group. All electric charging vehicle loads can be in aggregate.

If there are no renewable power sources or electric vehicle charging stations in this building, it is not required to separate the electrical circuits for electrical energy monitoring.

### 8.3.1 Compliance Methods

Electrical power distribution systems shall be designed so that measurement devices can monitor the electrical energy usage of load types according to Table 130.5-B. However, for each separate load type, up to 10 percent of the connected load may be of any other load type. Also, rather than prescriptive requirements, the Energy Standards allow any approach that provides the ability to measure the separate loads of the building.

The separation of electrical circuit requirement of §130.5(b) may be accomplished by any of the following example methods:

A. Method 1 (See Example 8-6): Switchboards, motor control centers, or panelboards loads can be disaggregated for each load type, allowing energy measurement of each load type independently and readily. This method must permit permanent measurement and determination of actual interval demand load value for each disaggregated load in the system.

This is a straightforward approach for taking energy measurement of each load type, as each equipment serves a single load type. Summation of the kVA measurement of the distribution equipment in accordance with the respective load type can result in the energy usage of each load type. This method is simple and straightforward in terms of the effort required in compiling the measurement data.

B. Method 2 (See Example 8-7): Switchboards, motor control centers, or panelboards may supply other distribution equipment with the associated loads disaggregated for each load type. The measured interval demand load for each piece of distribution equipment must be able to be added or subtracted from other distribution equipment supplying them. This method must permit permanent measurement and determination of actual interval demand load value for each disaggregated load in the system.

This method allows distribution equipment to serve more than one load type while allowing the separate energy use of each load to be determined. More effort may be required in terms of treatment of the measured energy data to obtain the energy usage of each load type.

C. Method 3 (See Example 8-8): Switchboards, motor control centers, or panelboards may supply more than one load type as long as each branch circuit serves a single load type and the equipment includes provisions for adding branch circuit monitoring in the future. For example, neighboring branch circuits in a panelboard may serve receptacles and fans respectively, but any circuit of that panelboard cannot serve a mixed type of loads. Also, there is no mandatory requirement to include branch circuit monitoring at this time.

D. Method 4: Buildings for which a complete metering and measurement system is provided so that it can measure and report the loads by type.

This method allows a complete metering system to be used to meet the requirements of §130.5(b), provided that at a minimum the system measures and reports the loads called for in Table 130.5-B of the Energy Standards. Such an installation goes beyond the requirement of the Energy Standards as it meters and measures the power and energy usage of each load type. It provides benefits for building owner and operators by giving them a readily available tool for assessing the building energy usage as soon as the facility is turned over to them.

Example 8-6

Question:

I am working on a new building project of a nonresidential building with a service less than 250 kVA but more than 50 kVA. Following is the proposed concept layout of separation of circuits for connecting different load types to the service equipment. Does this concept meet the requirements of the Energy Standards?

Answer:

The proposed design meets the separation of electrical circuit requirement of §130.5(b) as there are separations of circuits for connecting different load types to the service equipment. There should be provisions including physical spaces for future setup of measurement devices for energy monitoring at each electrical installation location.

Example 8-7

Question:

Part of my proposed design is to use a distribution panel serving HVAC loads, with the panel also feeding a lighting panelboard. There is another, separate panelboard serving plug loads only.

Does this design meet the requirements of the Energy Standards?

Answer:

The proposed design meets the separation of electrical circuit requirement of §130.5(b) as each load type in the building can be accounted for by addition and subtraction of the measured energy data, as indicated in Method 2.

Example 8-8

Question:

Can a panelboard with provisions allowing branch circuit energy monitoring be used to meet the separation of electrical circuits requirement? Each circuit would serve no more than one load type. Does this design meet the requirements of the Energy Standards?

Answer:

The proposed design allows each load type to be separately measured for energy usage and, therefore, meets the requirements of §130.5(b).

### 8.3.2 Application Considerations

The Energy Standards envision the use of conventional panelboards, motor control centers, panelboards, and other standard wiring methods for meeting the requirement to separate electrical loads. The requirement may also be achieved by a well-planned wiring approach, such as connecting all HVAC units to a single feeder from the service using a combination of through feeds and taps. The regulations are intentionally written to specify the “what” without prescribing the “how,” and, thus, provide as much flexibility as possible.

In a “typical” small building with a service size of 50 kVA or less, separation of electrical loads is not required for the building loads, except for any renewable power sources (solar PV systems) and electric vehicle charging stations installed at the building.

In buildings with a larger service between 50 kVA and 250 kVA, separate risers for lighting, receptacles/equipment, and HVAC are allowed to be used for meeting the separation of electrical circuits requirement. Large loads or groups of loads, such as an elevator machine room or a commercial kitchen, may be connected to panelboards or motor control centers served by a dedicated feeder, and the electrical power and energy of the entire group of loads can be measured by metering the feeder.

For buildings with services rated more than 250 kVA, lighting and plug loads are required to be separated “by floor, type or area.” So, in a single-story building, all the lighting loads could be fed from a single panel, and all the plug loads could be fed from another panel (or, alternatively, both types of loads could be fed from one panel with provision to allow for future metering for each load type – metering data available can further be organized, compiled, and viewed with software or mobile apps for each load type).

In a multistory building, a simple way to comply would be to install a separate lighting panel and a separate plug-load panel for each floor of the building. However, it would be equally acceptable (and may be more useful) to divide the load according to which area of the building it serves (office, warehouse, corridors, and so forth) or by the type of light fixture (metal halide vs. fluorescent, dimmable vs. fixed output). So, for instance, the first and second floor office lights could be fed from the same panel, while the warehouse lights would be fed from a second panel. Dividing the load by area or by type instead of by floor is more likely to yield useful information when the loads are analyzed in an energy audit. All these approaches are available to designers and installers and are acceptable methods of complying with the Energy Standards.