At 06:33 PM 10/24/2012, neil n wrote:
>I'm installing H4 round headlights with 80/100 Watt bulbs. ('88 Westy)
>I saw Alistair's diagrams (thank you Alistair!).
>
>Using P = IE at ~ 13 Volts 100 Watts is 7.7 Amps
>
>Stock fuses are 10 Amps each.

Ur doing it rong. ;-)

Size your fuses according to the ampacity of the wires in the
circuit, not the amount of current drawn by the load.  Otherwise you
will lose more power than necessary in the fuse and have more chance
of a false blow.

The fuses are to protect the wiring, *not* the load.

Yours,
David