What minimum fuse rating is needed for a 12 volt circuit with just one 48 watt bulb?
Answers:
The working lamp will draw 4A at 12v due to the resistance of the filament, HOWEVER, when first switched on the current will spike quite high (about 8 or 9A) for a fraction of a second as the filament has a much lower resistance before it gets white hot.
Standard automotive fuses are not classified as 'quick', so I'd be tempted to put in 10A fuses per lamp. Running the lamp at 4A, with a 4.5 or 5a fuse WILL overheat the fuses as the current flow is near to the maximum, this can cause the fuse box to overheat.even to the extent of causing fire.
Fuses are in place to protect against short-circuits when the current will rise to cable melting proportions!!
A typical 2x headlamp arrangement has between a 20A and a 30A fuse in it.
Hmmm. let's see. A 48 watt bulb will draw 4 amps at twelve volts, so how about a 5 amp fuse?
4amp I believe
As the bulb requires 4A, add a safety margin of 10% to rate the fuse at 4.5 Amp
4.5 or 5 amp fuses
In theory, four amps---this is with direct current only!
Basic 4amp but use a 5
The answers post by the user, for information only, UKQnA.com does not guarantee the right.