fuses

[Piero franchi]

Hi
I have been following a few threds here re fitting a lager/more fuses to our cars,

Its been on the cards for a long time now,

What I dont understand is why some say to use what I would say as high value fueses.

The whole point of splitting up the curcit and adding extra fuses it to save the wiring incase of a fault.

I see some are quoting 20 amp as a heater motor or window wiper motor,

having had a look at the manuel, the value of a heater motor in second speed is no more than 3 amps   :-/

I know there is a surge with electric motors but surly not 15 pluss amps.

If I was to attach a meter from a battery to the input side of a moror and the switch it to grown, would the meter read the surge than the current it settels down to

many thanks

[piman]

Hello Piero,

it's very difficult to get an accurate current reading at motor start with a meter, but an analogue meter might give a better idea?
Just to confuse you the glass Lucas fuses are rated at blow current not circuit rating and is approximately half the value of normal fuse ratings.
Normally car fuses are to protect against short circuits to earth so reasonably 'strong' fuses can be used as the short circuit current is pretty high so the fuse will blow in that case. if you fuse closer to the true circuit load you may experience nuisance blowing as the fuses degrade over time.

Alec

[Piero franchi]

Just as a guide, what modern fuse rating should I use for wiper motor.
Heater fan
Stop lights only
Main lights before a relay

[piman]

Hello Piero,

I'd go for something like, in order, 15, 10 and 20

Alec