The fuse is there to protect BOTH the device and the wiring. It
should NEVER exceed the rating set by the device manufacturer which
will usually have a bit in reserve.
> Picking fuse/breaker ratings with respect to the device's nominal
> current draw may not allow for inrush current.
Use an anti-surge or Slo-Blo fuse.
> OTOH, if wire size selection has been conservative, I'd use caution
> in placing too high a fuse/breaker rating on something that's really
> expensive. Sometimes an avionics mfr. will specify even 16 ga. be
> used on the 14V line, even though the box draws, say, 1.3 A. But if
> the fault inside were to kick the draw to just below a 10-amp
> fuse/breaker, you could be slowly cooking component$ inside that are
> not initially defective and frying traces off a PCB board.
I agree absolutely, but not just the expensive equipment. I've seen
clouds of fumes coming out of a ham transmitter than had been fitted
with a 10 amp fuse after the original 5 amp fuse had blown. I don't
know how toxic the fumes were but they certainly reduced visibility.
Please, take great care.
Peter Barwick
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