CT Sensors - Monitoring Dual-Pole/Multi-Pole Circuits and using Multipliers

Dual pole (and multi-pole) circuits are the kinds of circuits in your panel that include two lines (or more) to power the connected appliance/load.

Above: Highlighted dual pole breaker. It is not uncommon for dual pole breakers to have a "tab" that connects the two breaker switches together so if either trips, they both do.

There are two ways these types of circuits can be monitored with a Gen 1 or Gen 2 device:

1.) The first and most accurate method to monitor these kinds of circuits would be to attach a single sensor to each leg of the circuit. This method will accurately capture the measurements of the entire circuit. Right now in the application they'll show up as individual circuits, but we're working on functionality that will allow us to "combine" circuits within the app for easier understanding.

Above: Two sensors with one CT placed on each leg of the dual pole circuit. No multipliers are required in this scenario.

2.) The other method of monitoring these kinds of circuits involves using a single sensor on one leg of the multi-leg circuit and setting a multiplier in the application. This is a great way to conserve a sensor to use to monitor a different circuit, but can add some inaccuracy to the measurements as we're "assuming" equal usage on the other leg of the circuit. In many cases this is acceptable as the difference will be negligible, however for some appliances the difference can be quite large. Sub-panels can have even larger differences between the provided lines of service, so its generally recommended to not use multipliers on those kinds of circuits. More details about using multipliers can be found here.

Above: One sensor attached to a single leg of the two leg, dual pole circuit.

Below: Highlighted screenshot of settings in App to set multipliers for circuits.

To set a multiplier in the app for a specific circuit, we can do the following:

1. Select the Menu (☰) in top left corner
2. Select Manage Devices under Settings
3. Select device you want to make changes to
4. Select circuit you want to add the multiplier to
5. Change multiplier field to 2.00 (for dual pole breaker) and hit Save

Conclusion:

It comes down to a trade-off between accuracy and sensor count. The "correct" answer is related to your energy monitoring goals. If you have any questions or would like any clarification about how to monitor a dual pole (or more) circuit, feel free to reach out to the Emporia Support team directly.

Feedback and Suggestions

This knowledge base is pretty new for the Emporia team. Our goal is to provide all of the information we can to help you manage your energy in better ways. If this article wasn't helpful, or we could be more clarifying on any points please reach out to the Customer Support team and we'll certainly work to improve these guides.