Non-invasive current transformer. Use this sensor clip to build your own Personal Energy Monitor.
Current transformers (CTs) are sensors that are used for measuring alternating current. They are particularly useful for measuring whole building electricity consumption (or generation for that matter).
The split core type such as the CT in the picture above, is particularly suitable for DIY use it can be clipped straight on to either the live or neutral wire coming into the building without having to do any high voltage electrical work.
NOTE: Colour might change due to different batches.