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# How does an electric meter work?
- URL: https://www.ampmyhome.com/electricity/how-does-an-electric-meter-work/
- Published: 2025-07-24T15:18:28.000Z
- Updated: 2025-07-24T21:01:11.000Z
- Description: It’s how you get billed - and a bunch more.
- Author: Eric Moyer
- Tags: Electricity, General

An electric meter measures the amount of electrical energy a home or building uses over time, in kilowatt-hours (kWh). Simple enough - but there’s way more to it.

### 🔌 Basic Principle of an Electric Meter

Electric meters track the flow of electricity through the main service line coming into your home. They measure:

**Voltage (V)** – the "pressure" that pushes electric current.  
**Current (A)** – the flow of electricity.  
The product of voltage × current × time gives [**Energy**](https://www.ampmyhome.com/electricity/energy-units-of-measure-in-the-home/), recorded in **kWh.**

## Mechanical Electric Meters 

In the old days (say, 2009 and before) most electric meters were mechanical devices with a rotating aluminum disk that spins faster with higher electric use. Gears connect the spinning disk to a readout, with dials pointing to numbers or directly read out numbers much like old-style automotive odometers. These mechanical meters required a person - either the homeowner, or more likely an electric company worker, to read each meter monthly in order to generate a bill. [Wikipedia has a detailed history and descriptions](https://en.wikipedia.org/wiki/Electricity%5Fmeter?ref=ampmyhome.com) of these types of meters.

## Electronic “Smart” Meters

Today, most electric meters are electronic. I’ll describe how these work based off of my utility, PG&E, which is probably representative of other utilities in the US.

### ⚙️ 1\. Sensing Electricity

**Electronic measurement**: The meter employs solid-state sensors and microprocessors to continuously record voltage, current, and power consumption. This electronic approach improves accuracy over old spinning-disk meters

![Smart Meter block diagram](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/smart-meter-block-diagram.jpg)

Smart Meter Block Diagram (Toshiba makes chips for these, the pink blocks/TMP numbers)

### 🌐 2\. Communication with PG&E

Smart Meters communicate with PG&E over two-way radio links and other network elements back to PG&E's central systems. The main components include:

**Primary RF link (900 MHz)**: Every hour (residential) or every 15 minutes (commercial), the meter sends encrypted usage data via a [secure 900 MHz radio](https://wiki.recessim.com/view/Silver%5FSpring%5FNetworks%5FProtocol?ref=ampmyhome.com) to a another meter (in a mesh configuration) or to nearby data collector—often mounted on a utility pole. They call this the “Neighborhood Area Network”.

**Collector to utility network**: The poleside devices forward aggregated data over a cellular connection to PG&E’s central meter reading system.

**Integration with billing system**: The meter reading system is connected in to PG&E's billing system - which seems like it's quite an old, legacy system they want to [spend a lot of money](https://pelegri.substack.com/p/7613-million-for-a-billing-system) to replace.

![PG&E smart meter reading and billing system diagram](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/pge-smart-meter-diagram.jpg)

PG&E's Smart Meter reading and billing system

### 🏠 3\. In-Home Connectivity

PG&E SmartMeters include a [Zigbee](https://csa-iot.org/all-solutions/zigbee/?ref=ampmyhome.com) 2.4 GHz radio for communicating usage data to home energy devices (they call this the “Home Area Network”). For example, using a $40 [Emporia Vue Utility Connect device](https://www.emporiaenergy.com/how-the-vue-utility-connect-works/?ref=ampmyhome.com), you can see your own real-time electricity usage data on your phone or computer. (If you're feeling really ambitious, there's even a way to [hack the device](https://github.com/nekorevend/esphome-emporia-vue-utility/blob/main/README.md?ref=ampmyhome.com) to give real-time energy tracking in [Home Assistant](https://www.home-assistant.io/?ref=ampmyhome.com).)

![](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/emporia-vue-zigbee.png)

![](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/emporia-vue-utility-connect-device.jpg)

![](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/emporia-vue-utility-connect-usage-graph.jpg)

Real-time monitoring electricity usage from Smart Meter using Emporia device

### 🔒 4\. Two-Way, Secure and Remote Control

Two-way communication allows PG&E to push firmware updates and programming, and (in some cases) [remotely disable](https://abc7news.com/archive/7555472/?ref=ampmyhome.com) or enable service.

Data transmissions are encrypted and comparable in strength to everyday devices. For instance, the RF emissions are about 300× lower than a cell phone at 10 feet.

### 📊 5\. Benefits for You

**Hourly data tracking**: Log into your PG&E account to view energy usage, hour by hour. You can also connect this data to your own applications through API's, such as [Apple Home](https://support.apple.com/guide/iphone/view-electricity-usage-and-rates-iphb93a7973e/ios?ref=ampmyhome.com) and [Home Assistant](https://www.home-assistant.io/integrations/opower/?ref=ampmyhome.com). Unfortunately, this data is delayed by 2-3 days due to PG&E's systems.

**Time-of-use plans**: Smart meters enable dynamic billing based on when electricity is used—higher during peak hours and lower during off-peak periods. This can help you save money by using power during less expensive times of day.

### 📊 6\. Operational efficiencies and improvements 

PG&E has used their Smart Meter network and capabilities to improve their operational efficiencies:

**Reduce costs**: Obviously, they no longer need to send personnel around to each house every month to read the meters.

**Smart-grid features**: They're foundational to demand response programs, [virtual power plants](https://www.ampmyhome.com/electricity/virtual-power-plant-vpp-trials-bay-area/), outage detection, efficiency improvements, and wildfire prevention strategies. PG&E [outlined some of their past tests here](https://www.pge.com/assets/pge/docs/about/corporate-responsibility-and-sustainability/PGE-EPIC-Project-1.14.pdf?ref=ampmyhome.com) \- outage and restoration detection seems like it’s one of the bigger benefits.

### 🤔 7\. Health, Security, Privacy

**Health**: Studies show RF exposure from smart meters is minimal and significantly lower than common wireless devices

**Security**: PG&E uses encryption and network safeguards. Early versions had remote disconnect features disabled until security was verified. However as with any pools of electronic data and distributed systems, [cybersecurity is always a challenge](https://www.smart-energy.com/industry-sectors/smart-meters/how-hackers-target-smart-meters-to-attack-the-grid/?ref=ampmyhome.com).

**Privacy**: In California, there are laws that protect the privacy of utility customer information. However, as with many data collection activities, [sometimes this law gets broken](https://www.abc10.com/article/news/local/sacramento/sacramento-utilitys-data-sharing-police-triggers-privacy-lawsuit/103-f0ee2fe5-be29-4968-84db-2c4c88c141ab?ref=ampmyhome.com)!

### What else?

Recently, companies have started to take advantage of the fact that electric meters in the US “plug in” using a standard system - most residential systems use a “Form 2S” plug-in meter. [Eduardo explains](https://pelegri.substack.com/p/meters-and-meter-collars) how this enables all sorts of simplified solar, battery, and electric additions that require less manual labor.

![Electric meter collar installation](https://storage.ghost.io/c/70/c8/70c8e8a7-04e1-4bed-9ef1-c3a4705e5dc7/content/images/2025/07/tesla-meter-collar-exploded-view.png)

Simplified battery & solar installation with electric meter collar