side lights,
horn, 5 amps???
indicators/hazzards,
brake light/switch,

Plus 4 relays? worst case .25amps each???

I do not want to over load my switched live... I think my cable will take 16amps.

[Edited on 30/9/10 by dilley]

side lights - 5
horn - 5
indicators/hazzards - 10?
brake light/switch - 10

They are what i have mine fused at.

Amps=Watts/Volts

it depends on if your running leds or haolgen bulbs etc.

i would say the horn is a bit higher than 5A but again it depends on the horn your using.


as a rough guide

side - 4 * 5w
ind / hazard = 6*5 w
brake = 2*21 w

thats 92W, /12 = 7.6A

horn i would say is about the same again so with 16a you should be ok but i would make sure its fused correctly just incase.

if your running leds you will have a lot more to play with.

Just remember when selecting a fuse you're protecting the loom not the item itself. If the fuse blows it's often because the protected item has gone pete tong anyway

IE so if you're using 16a wire you really want to use absolute max 15A fuse...

Also don't forget diversity and time factor - you are not going to be using all the loads simultaneously for any length of time and as wires (and fuses) take time to heat up, you can actually take much higher loads for short periods. Look up fuse curves for more information.

The horn is a special case as it is an inductive load so it has to have a fairly beefy supply wire and fuse for 8 amps.
A horn relay is pretty essential or the horn switch won't last.

You don't need relays on any of the others but modern practice is to use a main relay for the ignition switched loads.

Hazards aren't wired through the ignition -- but direction indicators are. Current hrough indicators is about 3 to 4 amps (21 watt bulbs), hazards obviously take twice that.

Stop light current is 3 to 4 amps max unless you have a high level brake light then allow for 5 amps..
Stop lights are generally wired without a relay.
UK practice is to wire the stop lamps through the ignition switched supply but this is optional the French generally supply from a constantly live fuse.