Sense can use a single CT, per load, to monitor up to two dedicated 240V circuits if the load is not connected to the neutral bus (balanced 240V-only). However, in some cases, it’s also possible to monitor a 240V circuit connected to neutral (240V/120V) with just a single CT.
The following installation instructions are advanced and an electrician is required.
Please be advised that the method described below may not work in all electrical panels, depending on various physical factors such as the gauge of the wires, whether they are stranded or solid core, available cable slack, and available space within the electrical panel.
If the following method will not work for you, in many cases you’ll still be able to monitor a single 240V/120V device via the single 240V load method. 240V/120V loads should not be monitored with the 240V-only method, as both accuracy and broad device disaggregation issues can result.
Please ensure your Flex sensor cable is plugged into your Sense monitor before installing your sensors.
This method should only be used if you are monitoring two loads, either both 240V or 240V and 120V. If you’re attempting to monitor a single load and it’s a 240V load, please use the single 240V method.
1. Find the 240V/120V load you want to monitor in your electrical panel and turn off the breaker to the load.
2. Clamp one Flex sensor around both ungrounded conductors in such a way that one conductor goes through the sensor in reverse direction. Sensor orientation does not matter, provided one conductor enters the sensor via the reverse side. Refer to the included illustrations to show two possible methods.
NOTE: GFCI and AFCI breakers may be connected directly to the neutral bus with an additional wire. That wire should be ignored for the purposes of this installation.
If your second load is a 240V/120V load: Repeat steps 1 and 2 for that load.
If your second load is a 240V-only load: Find the load. Clamp one Flex sensor around either ungrounded conductor attached to the breaker. It does not matter which conductor the sensor is attached to. The direction of the Sense logo sticker on the sensor must face the circuit breaker.
If your second load is a 120V load: Find the load. Clamp one Flex sensor around the single ungrounded conductor attached to the breaker. The direction of the Sense logo sticker on the sensor must face the circuit breaker.
4. Write down the names and type (120V, 240V-only, or 240V/120V) of the devices you’ll be monitoring. You’ll need this information during in-app setup.
Important: The sensors must remain fully closed after installation. If the sensor is forced open, even slightly, by the conductors, this will result in inaccurate wattage readings.
Ensure both breakers are still in the ‘off’ position before returning to the core installation guide
You can install with the sensor in horizontal or vertical orientation.
Horizontal orientation may help to reduce lead tension and prevent the sensor from opening, while vertical orientation will work better in tight spaces, but requires more flexible conductors.
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