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914World.com _ 914World Garage _ Relay board fuse change

Posted by: porschetub Sep 25 2016, 03:29 PM

Have looped heater blower fan wiring to use for oil pressure circuit,want to downsize fuse from 25amp to just run a carter rotary LP carb pump,can't find the specs for my pump so don't know current draw,question is 10 or 15amp???
Thanks and

Posted by: porschetub Sep 25 2016, 03:54 PM

Finally found specs on Summit website...got a surprise as it only draws 4.5 amp,think a 5 amp fuse would be ok? interested in replies however.

Posted by: Mike Bellis Sep 25 2016, 04:17 PM

Run the 5A, if it blows bump up to 7.5A. Your fuse should be 125% of the circuit load value, unless you want to use the locked rotor current but that is only required for fire pumps...

Posted by: Mike Bellis Sep 25 2016, 04:20 PM

I should also mention, your fuse needs to be sized for FLA (full load amperage). Electric motors make full torque at startup. This will cause a current spike as the motor starts.

Posted by: porschetub Sep 25 2016, 04:32 PM

QUOTE(Mike Bellis @ Sep 26 2016, 10:17 AM)

Run the 5A, if it blows bump up to 7.5A. Your fuse should be 125% of the circuit load value, unless you want to use the locked rotor current but that is only required for fire pumps...

Thanks Mike,I think that was running current so a 7.5 it is