The clip on direct current measuring coils are very handy for tracing “sneak currents” in wires without cutting or disconnecting the wire.

These are called “Hall Effect” current sensors..
They used to cost $100 to $200 but have come down greatly in price.

https://www.fluke.com/en-us/learn/blog/clamps/inside-hall-effect-clamp-meters

https://www.amazon.com/BSIDE-ACM91-...Y2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=