Electrics help please - light bar harness

[Dan!]

Morning all,

This is a non Maserati issue before you all think I've gone completely mad.

I've bought a 540w light bar for my truck and need to wire it in properly. I plan to tap into the high beam live for a signal to a relay, then power the light via that relay.

Questions:
1. Which rating of relay do I need? I'm assuming 540w plus
2. What's the minimum guage of wire I should use to power the light?

 

[CatmanV2]

1) 50A would see you right (unless it's inductive) Power = V*I. 540=12*I ergo I = 540/12 = 45
2) No idea at all

C

 

[Dan!]

Cool thanks

 

[outrun]

****, are you planning on shooting wild boar at night again Daniel?

 

[Felonious Crud]

****, are you planning on shooting wild boar at night again Daniel?

No, locals. Dan gets terribly territorial in rutting season.

 

[FIFTY]

2. You are sending 540w over what distance? You need to account for the voltage drop over the distance of the cable.
There are loads of charts and calcs online if you search Google for it

 

[MGT]

Didn't fancy LEDs? Or is that 540w of LEDs?

 

[Navcorr]

 

[midlifecrisis]

2. You are sending 540w over what distance? You need to account for the voltage drop over the distance of the cable.
There are loads of charts and calcs online if you search Google for it

I wouldn't have thought that volts drop would be an issue on relatively short cabling. We're not talking three phase SWA here.