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AC Split-Core CTs (J&D)

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AC split-core CTs measures the amperage of a conductor on an AC (alternating current) system. Combined with voltage measurements, this allows calculation of power and energy values. AC CTs provided by eGauge are split-core, meaning they can be wrapped around a conductor instead of having to disconnect the conductor and feed it through the CT. For pricing and available models, see the online store.

This article covers CT diameters from 10mm (.39") to 36mm (1.42"). For larger sized CTs, see the Rope CT article or Large 50mm (2.00") CT article. It is recommended to use Rope CTs over the 50mm split-core CTs.

For C0.6 certified high-accuracy split-core CTs, see the High-Accuracy CT product page.


Standard split-core CTs in multiple sizes


Full specs (data-sheet PDF)

  • 333 mVrms at rated output
  • Accurate within 1% from 1% to 100% of rated amperage
  • Operates 50Hz/60Hz
  • Maximum primary insulation up to 600 Vrms
  • 8' twisted pair lead with CT connector
  • 1-year Limited Warranty

Hardware included

  • 1x J&D split-core CT with built-in 8 foot leads and 2-pin plug affixed

Assembly/installation information

See the Installation Overview Tips to get started.

  1. To reduce risk of electric shock, open or disconnect circuits from the power distribution system (or service) of the building before installing or serving CTs.

  2. Open the CT by gently pulling on the latch and then rotating the top open. Do not touch the polished ferrite core surfaces. Any oils or debris in that area worsens accuracy.
  3. Slide the CT over the conductor of the circuit to be measured. Make sure the sticker on the CT points in the direction of the primary current flow (the current flow that should yield a positive power reading).
  4. Close the CT by gently pushing down on top of the CT until the latch engages. Some CTs require 2 clicks to fully shut.
  5. Verify that the CT is fully closed by squeezing together the top and bottom parts of the CT.
  6. Optional: secure the CT to the conductor with a cable tie.
  7. Route the twisted pair wires of the CT to the meter such that they do not directly contact live terminals or bus bars.
  8. Plug the 2-pin terminal at the end of the twisted pair wires into an unused port on the meter.
  9. Configure the sensor input in the meter interface and complete the general configuration.
ct plug in egauge
CTs connected to eGauge meter.