Just finished installing relays for new white headlights and high beams(4 light car). The relays say they handle 30/40 amps. I was told that the lights put out 60 watts each-times four lights equals 240 watts. 240 divided by the voltage gives me the amps? If that is true, then each set of light is pulling 10 amps for each relay. The high beam relay get pretty hot - like can only touch itr for 5 seconds, then OOOWWW! I ran a number 10 wire from a new fuse block for the main relay power wire, although the wires themselves were not hot. What do you folks think? Bad relay? Thanks

60 watts divided by 12 volts = 5 amps per circuit.

For future reference:


http://www.chevelles.com/showroom/data/500/ohmslaw.jpg

I think you need to measure the current that the lamps actually draw to make the calculation. Headlamps are not constant power loads, they vary greatly depending on voltage.
If the relay is that hot the relay is either defective or badly rated (as a lot of the after market Chinese relays are).

Ron

Good advice to check the actual current draw. I measured my H4 lamps that are labeled as 60/55W and found at 14V one headlight draws:
low beam: 3.2A (=45W)
high beam: 4.8A (=67W)
Your wattage may vary.

Four headlights on high beam could draw nearly 20A, so the relay will get warm. If it gets too hot to touch, check the quality of connections to the relay. If you solder the wires to their female spade connectors instead of relying on crimp connections, this could help reduce the heat.