@Mellow Hudson Mike posted:Why? The current is interrupted through the entire path at essentially the same time (given the speed of electrons). It's not interrupted near the source any quicker than the at the far end.
Therefore a traditional breaker or fuse can go anywhere along the path. Everything in that path is protected simultaneously and to the same degree.
(Electronic breakers are a different story because they need to be powered in order to do their job. Where that power comes from is important, but not with traditional fuses and breakers which need no external power to determine that excessive current is flowing.)
Mike
The TIU is a 2 terminal device ACROSS the hot and common. It can short and fail internally as a short (most times the internal TVS shorting). A breaker/fuse after this will never detect that short.
I understand your thought process, but again, just like a switch- everything before the breaker/fuse is still connected- still live, still "hot". If that device has a return path and internal circuitry that can fail- the short bypasses the breaker completely.
