The Accu-CT® ACT-1250 family of current transformers contain internal burden resistors to provide a 333.33 mVac output at rated current. If you are using an ACT-1250 CT with something other than a WattNode® meter, you may need to know the effective output impedance of different CT models to compute the effect of external loading on the accuracy. The following table provides the burden resistance (equivalent to the output impedance) for common models. Contact CCS support for other models.

Model Burden Resistance
ACT-1250-250 8.0 ohms
ACT-1250-400 5.0 ohms
ACT-1250-600 3.3 ohms
ACT-1250-250 Opt 1V 24.0 ohms
ACT-1250-400 Opt 1V 15.0 ohms
ACT-1250-600 Opt 1V 10.0 ohms
  • Note: these values also apply for Option C0.6, Option C0.3, and Option HF.

See Also