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I don't think you need to change your
breakers. If you re-read my post, I think you'll see that you're
fine with what you have. CB's are (typically) designed so that you
size them at around 10-20% above normal continuous load, and their
designed-in protection delay curve allows for surges. Fast blow
fuses, on the other hand, must be sized so that the maximum surge
load is well below the rating on the fuse. That's almost certainly
why your 10A CB's work fine, but his 10A fuses are blowing. The
Walbro seems to run at between 6 & 10 amps, but can surge to
(I'm guessing now) probably around 15 amps in some circumstances.
Hence, the 20A (fast-blow) fuse requirement.
BTW, contrary to popular belief, the fuse or breaker is there to
protect the wire, not the device. If you upsize to a 20A CB, can
your wire handle 40 amps for up to 20 seconds without melting the
insulation?
Charlie
On 3/17/2017 9:29 AM, Jeff Whaley wrote:
Thanks Charlie,
yes checked the Spruce website myself and can see the 20 Amp
marking on their pump image. Will visually check my pumps
- if they are stamped “20 Amps”, I’ll order two of the
Tyco parts in 20 Amp. I have been fine so far but
double-fine is better.
Jeff
Image of the Walbro attached.
Around the curve is the word 'required'.
If you download the data
sheet (available on the Spruce product page), it'll show
that a 200% load (20 amps, in this case) takes anywhere from
6 to 22 seconds to trip the breaker. So you're fine. In
contrast, Littlefuse brand ATC blade fuses are rated to blow
in 0.75 to 1.8 seconds at a 135% (13.5 amps) load.
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