Fuse size for headlight relays

[colinbg]

I have just wired up a separate fuse board and fitted 4 x relays 2 for main beam and 2 for headlights but i am not sure what size fuses to fit for the supply to the relays the headlight bulbs are standard headlights i have not upgraded them yet i thought i wound upgrade the wiring first thank you Colin.

[enigmas]

Here's a useful link to the MGA guru.

mgaguru.com/mgtech/electric/et206a.htm

There's a simple equation for selecting the appropriate fuse based on the total wattage of the lights on that particular circuit. Here's an excerpt below.

"Assuming you do not exceed 60 watts pre bulb, then (2x60W)/12V=10 Amps. This is why my schematic calls for 10 amp relays. Fuses are called as 15 amps, as a fuse or circuit breaker should be rated at least 20% higher than the expected load to avoid blowing the fuse in normal use. If for any reason you do install lamps greater than 60 watts, then up rate the relays and fuses and wire size accordingly."

[petervdvelde]

Vince,

Colin used a separate relay for each light so i believe the current is 1x60 watt/ 12v = 5Amps.

Peter

[enigmas]

Yes, I know Peter. I posted the link to illustrate how to calculate the fuse value.

As an aside, 5amps is truly a light weight fuse...even if the calculation arrives at it!

[colinbg]

Thank you for the link and explaining how to calculate the correct fuse needed thank you both again.