Parallel Danger? [RE-wrenches]

[Ray Walters]

Hi Bill and all;

Here is another potentially dangerous situation to ponder: a 5amp UL listed
device (a computer) is powered through 16 awg SJO cord to a 15 amp rated
receptacle. This receptacle is PARALLELED with several other 15 amp rated
receptacles (35cents made in China). This whole circuit is fed through a 20
amp breaker. Coffee spills on the computer creating a short. Because of the
time/ current performance of the breaker, over a hundred amps could pour
into our soaked device for a few seconds and  20 amps could flow
continuously into a device UL listed for only 5.
Compare this scenario, with my maligned array wiring method: two array
strings each having a short circuit output of 4.75 amps and a series fuse
rating of 15 amps feed thru 12 awg wire  in parallel for a total of 9.5
amps to a 15 amp breaker. A moose chews through the wire creating a short.
Up to 15 amps continuous are allowed to backfeed into the circuit ( the
charge controller also failed) and are boosted another 4.75 amps by the
paralleled string. This time almost 20 amps could possibly (but not
probably because of the high resistance) flow into a device UL listed for
only 15.
Why is the first condition allowed, but the second is not? Is 120 vac safer
than 48 vdc?

Sincerely again,

Ray

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