Can Current Transformer cables be extended?

Current Transformer (CT) cables on the 6M & 6W series can be extended

CT cables can usually be extended to 10 meters while maintaining accuracy, using:

  • CAT5/6 data communication cable that conforms to a common data communication wire standard UL2464.
  • Two conductors that are twisted together (to reduce induced currents from adjacent magnetic fields)
  • Double insulation on the cable and join, making it easy to pull cables through boards and conduits.

Regulations require that the cable be:

  • Non-flammable (if exposed to flame it should not continue to burn)
  • Rated to 300Vrms
  • Double-insulated

Follow the rules that apply to your jurisdiction.

For longer CT cable extensions, or noisy electrical environments, we recommend this test

  1. Close the CT without a cable in the clamp
  2. Connect the CT to the Auditor with a current meter in series
  3. Check that the measured current is below 34mArms*

*Currents above 34mA are above the 'noise-floor' of the Auditor and contribute to Auditor kWh measurements that may cause inaccuracies. 

What cables do the 6M & 6W Current Transformers come with?

Wattwatchers Auditor 6W and 6M series use split-core CT clamps.  The cables for the CT's supplied by Wattwatchers are 1.8m long, with conductors stripped and tinned so that the multi-strand wires are easily inserted into the CT connector.

Wattwatchers CT cables:

  • Conform to UL2464 and are double-insulated.
  • Have two conductors that are twisted together to reduce induced currents from adjacent magnetic fields.
  • Have pink (+ve) and white (-ve) insulation over the two wires
  • Are flexible and white, with an outside diameter of 3.6 mm