On 10/18/2017 5:41 PM, jimlux wrote:
h, the fine problem of the meaning of words in different contexts - in
Electrical Code land - bonding could well be done by the coax shield,
with a couple potential problems:
1a) You'd have to make some reasonable case about what a plausible
fault current might be - this is the beauty of Class 2 Energy Limited
devices (your doorbell)- the maximum fault current is quite low, so
almost anything works. If you're running coax to something also
supplied by an AC power cord, it's a bit trickier. Probably would
depend on the fusing or overcurrent protection of the power supply.
There are two other issues related to power. Code requires that the
equipment ground (green wire) be run with the phase and neutral
conductors. First, if the equipment ground for the power system and the
phase conductor don't follow the same path, a fault (phase shorted to
ground) forms an inductive loop, the impedance of which can delay the
operation of the circuit breaker or fuse. Second, if the separately run
equipment ground is broken by some failure, the equipment is no longer
protected. This is equivalent to what you had noted with "unplugging
the coax."
73, Jim K9YC
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