CT Sizes

Wattwatchers sells a range of spilt-core current transformers (CTs) in different current ratings of 60A, 120A, 400A and 600A to support a range of customer loads and applications.

Each CT is a different physical size, and there is a maximum wire diameter that the CT will fit around as described in the following table.

Maximum Current Rating (A)	Opening Diameter (mm)
60	10
120	16
400	25
600	36

CTs are accurate over a range of 1000:1. For example, the 400A is 0.5% accurate at 400A and below 1A. Using a larger than necessary CT (with respect to the maximum current rating of the CT) does not affect the accuracy unless the currents are very small, in which case it probably doesn't matter anyway.

Wattwachers also has a Rogowski Coil option for site with large current up to 3000A or sites where a more flexible installation may be required.

Please refer to our CT Specifications document attached to this article for more detailed technical information.