5: We see that the current in the main bus is zero past
this point. This means we have passed the branch
circuit with the short.
5
feeder was apparently added to the very end of an industrial sid-
ing rail, far from the other feeders in that section of the layout. It
was hidden from view beneath by the lamp, and virtually invisible
from above. (see the yellow arrow in fig 3.) Amazingly, it took us
less time to locate this longtime gremlin with the clamp-on cur-
rent meter than it has taken me to write about it.
The clamp-on ammeter I purchased also includes volt and ohm
functions, but the ranges are very limited, and of little use for
testing DCC. I doubt that the actual amp reading is accurate due
to the differences between the normal AC waveform and that
of DCC. However, for our troubleshooting purposes, precise val-
ues are unimportant. We just need to see which way that ornery
short-circuit current goes at each junction between wires.
