Donut-style CTs require more effort to install but are less obtrusive and cheaper then Split-style CTs. The wire has to be removed from the breaker and the CT has to be slid over.
Split-style CTs are larger than and more expensive than the Donut-style CTs but don’t require the breaker wire to be removed. They’re commonly used on Main breakers as the wires can’t be disconnected from the main breaker.
For more information on the different installations of each CT style, click this link.
Posted in: Current Transformer (CT) Selection