This article covers CT installation topics such as placement, orientation, port assignments, and special configurations.

For the full hardware installation guide including wire harness setup, see our Product Documentation. For CT types, specifications, and how to choose the right sensor, see How CT Sensors Work.

The number of 200A main CT sensors you need depends on your system type:

For branch circuits, use one 50A CT per circuit you want to monitor individually — up to 16 per Vue.

If you only want to monitor a single feeder or circuit breaker, see Can I use a 200A CT sensor to monitor a branch circuit? under the Common Questions section below.

200A CTs work correctly on any panel size up to 250A, including sub-panels. No lower-rated sensor needed.

Not sure which system type you have? Check your main breaker label or consult a licensed electrician.

The Vue has two types of ports, and the app treats them differently. This is important to understand when planning your installation. The Vue 3 automatically identifies the phase and voltage on each port, you do not need to match a specific sensor to a specific port number or order.

Dedicated monitor:

If you want to monitor a single high-draw circuit or feeder using main ports, you can dedicate an entire Vue to that purpose. In this case, use the main 200A CT sensors on the main ports for your system type, leaving branch ports 1–16 empty unless monitoring a related sub-panel's individual breakers on the same device. For more detailed instructions, see Can I use a 200A CT sensor to monitor a branch circuit? under the Common Questions section below.

Don't cross panels:

Each Vue monitors one electrical system. Do not use branch ports on one Vue to monitor circuits from a separate, unrelated panel. Readings will be calculated against the wrong mains total, producing inaccurate results.

CT sensors do not need to be placed at the breaker itself. They can be positioned anywhere along the wire — at the breaker, midway, or closer to the load. This is useful when space near the breaker is tight.

Each CT sensor has a directional arrow labeled "Breaker" on the clamp body. This arrow should point toward the breaker on every circuit, away from the load or appliance.

For solar and generation circuits, current direction is managed through the Bi-Directional circuit setting in the app rather than physically flipping the sensor. See Solar Monitoring for setup details.

Dual-pole and multi-pole breakers supply 240V to large appliances like electric water heaters, dryers, air conditioners, EV chargers, and electric ranges. These circuits have two hot legs rather than one. You have two options for monitoring these:

This is the most accurate approach.

This is recommended for sub-panels, appliances with a neutral wire return, appliances with both 240V heating elements and 120V control components (like dryers or ranges), and any circuit where load may be unbalanced between the two legs.

Only acceptable for confirmed balanced loads with no neutral return, such as EV chargers or circuits with no neutral current.

This conserves a sensor port and works well for balanced 240V loads. It is not suitable for unbalanced loads, as those will overstate or understate actual usage.

For single-pole breakers, 240V breakers with one sensor per leg, and European single-phase systems, the default multiplier of 1.0 is correct, no changes needed.

Vue Gen 1 mains: Older Vue Gen 1 devices still require a 2.0 multiplier on the mains for 240V split-phase systems. The Gen 2 and Gen 3 measure voltage directly and adjust automatically — do not apply a mains multiplier on those generations.

As a general rule, each sensor should encircle only one wire. This provides the most accurate measurement for that circuit.

Exception — multiple same-phase wires:

It is acceptable to run more than one wire through a single sensor, provided all wires are from the same phase. The sensor will measure the combined total current from all wires inside the clamp and report it as one reading.

Keep in mind the current limits of the CT and port when running multiple wires through one sensor:

Never mix phases through a single sensor:

Placing wires from two different phases inside one sensor causes the currents to partially cancel each other, resulting in significantly understated readings.

This is a common installation mistake in split-phase panels where breakers alternate phases down each column.

Flexible Sensors install differently from rigid 200A or 50A CTs. They're Rogowski coils paired with active integrators, and they need their own power supply. The full step-by-step install reference is the Flexible Current Sensors Installation Guide. This section covers the points specific to flex sensors that differ from rigid CT install.

What ships in the kit:

Each Rogowski coil has a directional label on the body. The label must point AWAY from the breakers — the white label faces the service entrance side of the panel. Installing with the label facing the wrong direction inverts your readings, the same effect as a reversed rigid CT. Confirm orientation before closing the coil clasp.

Wiring scenarios for the flex sensor power supply. The flex sensor power supply needs its own breaker landing in addition to the Vue's wire harness. The right wiring depends on how many empty breakers you have and how many main CTs you've installed. The four scenarios in the install guide are:

For the exact wiring diagram for your scenario, see Steps 7a–7d in the Flexible Current Sensors Installation Guide.

Flexible Sensor specifications

Swapping CT sensors between port types is not a recommended configuration and should only be considered when no other option is available.

Both the CT sensors and the ports they connect to have independent limitations. Swapping a sensor between port types does not change or remove these limitations.

The only valid reason to swap is physical sizing. Before attempting a swap, exhaust the alternatives first.

Note: the screw terminal plug required for these conversions are not sold by Emporia. It must be sourced third-party or harvested from a spare CT sensor.

Converting a 200A CT to a branch port does not raise the port's current limit. The 63A accuracy cap is a property of both the 50A CT sensors and branch port itself. The only benefit to converting a 200A CT to a side port is to fit larger wiring that the standard 50A clamp is too small for. The better solution is a large-diameter 50A CT:

If the large-diameter 50A also doesn't fit: the 200A CT shares the same 22mm inner diameter window. If one doesn't fit, neither will the other.

If a 200A CT on a branch port is the only available option:

Note: the 4.0× multiplier is designed for dual-pole circuit monitoring, not as a CT conversion factor. It scales kW, cost, and volts, but not amps. Amp and volt readings on a converted port will display incorrectly; this is expected behavior, not a sensor fault.
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​Important: This is a physical sizing accommodation only. The branch port's 63A accuracy cap still applies regardless of which CT is installed. For circuits regularly drawing above 63A, a dedicated Vue with main port (A, B, C) monitoring is the correct solution.

This configuration is rarely needed and only makes sense if you have a spare 50A CT you'd like to put to use. A 200A CT will accurately monitor any circuit size including small ones. There's no benefit to downsizing to a 50A CT on a main port unless it's simply what you have available.

Step-by-step:

Important: 50A CTs saturate above 63A. Using a 50A CT on main ports A, B, or C will still have this limitation. If surpassed, readings will be inaccurate.

No. The 50A sensors on branch circuits operate independently and do not require the 200A sensors to function. If you only want to monitor individual circuits and are not interested in whole-home totals, you can leave the 200A sensors disconnected.

When the 200A sensors are not connected, the app adjusts automatically:

If space in your panel makes installing standard 200A clamp sensors difficult, Flexible Sensors are designed for tight spaces and can monitor your main service cables from a different position. Note that the small Flexible Sensor power unit also requires panel space.

Yes! This is typically done for two specific scenarios:

In this configuration, clamp the 200A CTs directly on the circuit's conductors and connect to ports A, B, or C as you would for mains monitoring. No multiplier or conversion is needed.

Important — keep branch ports 1–16 empty in this configuration. The app calculates Balance and circuit percentages by comparing branch port readings against the main port total. If branch circuits from a separate load are connected on the same device, the app will compare them against the wrong reference total, producing incorrect Balance and usage calculations. The only exception is monitoring a sub-panel this way. In that case, branch ports 1–16 can be used for the sub-panel's individual breakers, since all circuits belong to the same downstream load being measured by the main ports.

Yes, CT sensor wires can be extended or shortened. There are polarity and gauge requirements to follow to avoid incorrect readings or signal loss. For full specifications and step-by-step instructions, see Adjusting CT Wire Length.

This is typically caused by calibrating the device while actively exporting solar back to the grid, causing the Vue to mark the current direction incorrectly. See Solar Monitoring and Solar / Net Metering Wrong for calibration guidance and how to correct the direction in the app.

Don't see your question? Contact our Customer Support!

This knowledge base is continuously updated to provide the most helpful guidance for Emporia customers. If you found this article unclear or have suggestions for improvement, please contact our Customer Support team.