question about rock lights

dove'd85 · Dec 24, 2009

a couple of years ago i bought 6 of the TG rock lights made by grate.. they are 55 watts, when i had them in my last rig i put two light in a circuit and had three seperate circuits.

what i really want to no is what kind of amps does a 55 watt flood/tractor light draw and can i run 6 in one circuit on a 30 amp switch with say 8 or 10 gauge wire? without over doing the switch?

TIA

Clark · Dec 24, 2009

you need to use this formula,

watts/volts=amps

55watts/12volts=4.583amps that's per light. that's 27.498amps for 6 lights at 12 volts.

Your wire size is based on length of the wire, and amperage. I would not run that much power without a relay. That's like having your highbeams,lowbeams, and foglights all wired to ONE switch.

As for the wire size i'll bet there's a chart on what size is rated for what but you'll have to look that up.

Fordzuki · Dec 24, 2009

watts/volts=amps. so 4.6 amps per lamp. 26.7 amps, so technically yes, but I'd throw them on a 40amp relay with that switched.

Edit: Beat me to it Clark. :haha::awesomework:

RusM · Dec 24, 2009

http://www.powerstream.com/Wire_Size.htm

dove'd85 · Dec 24, 2009

thanks for the great info everyone

one more thing should i up my 30 amp switch to a 40 amp switch just to be on the safe side with a 40 amp relay wired inbetween the switch and the battery?

Clark · Dec 24, 2009

sounds good, and i'd use a 30A fuse for the relay power.

dove'd85 · Dec 24, 2009

RusM said:
http://www.powerstream.com/Wire_Size.htm

thanks for the link, though i don't understand it completely im sure, but for everyone 1000 feet of 8 gauge it adds

8 0.1285 3.2639 0.6282 2.060496 73 24 1650 Hz less then one more amp of resistance to the circuit?

Clark · Dec 24, 2009

dove'd85 said:
thanks for the link, though i don't understand it completely im sure, but for everyone 1000 feet of 8 gauge it adds

8 0.1285 3.2639 0.6282 2.060496 73 24 1650 Hz less then one more amp of resistance to the circuit?

that is irrelevant for what you're doing.

Pat · Dec 24, 2009

No you don't need a 40 amp switch that is what the relay is for.

Clark · Dec 24, 2009

Pat said:
No you don't need a 40 amp switch that is what the relay is for.

true, theoretically any switch will work if you're using a relay.

dove'd85 · Dec 25, 2009

ok awesome thanks for the help can i get a 40 amp relay at the local battery store or will i need to go to the junk yard?:redneck:

Clark · Dec 25, 2009

i've never been to a battery store, but any autoparts store should have one. I wouldn't get one from the junkyard.

86tuning · Dec 25, 2009

30A relays are something like $5 from car stereo shops. if you're concerned about current, run 2 of them. But a 30A relay will work fine for a 30A load. They have a bit of safeguard designed into them.

14ga wiring should work fine for all your lighting. Just double-up the wire from the battery to the relay. And run a fuse within 18" of the battery so that you don't start a fire if you pinch a wire against your frame.

zukkev · Dec 25, 2009

86tuning said:
30A relays are something like $5 from car stereo shops. if you're concerned about current, run 2 of them. But a 30A relay will work fine for a 30A load. They have a bit of safeguard designed into them.

14ga wiring should work fine for all your lighting. Just double-up the wire from the battery to the relay. And run a fuse within 18" of the battery so that you don't start a fire if you pinch a wire against your frame.

If you run a 30A relay in a circuit pulling near 30A continuous...you will have problems...and NO, 14GA is not heavy enough wire for a 30A circuit...and instead of doubling up 14GA for the load side power source, why not just run a single 10GA wire with a good quality fuse holder; much cleaner setup IMHO...
Now, for the trigger side of the relay, 14GA would be ok, as it doesn't 'carry' the main load...:awesomework:

Fordzuki · Dec 25, 2009

I have found that most auto parts stores don't carry universal relays. :eeek: Your best bet would be the mom and pops parts stores, National and BLAP both carry them in this area. The only relay I could find at shucks or autozone was part of a foglight wiring kit, which came with a 40 amp relay.
And as for 30 amp vs. 40 amp relays, just think of the 40 amp as a "heavy duty", while the 30 amp might work for what you're doing, the 40 amp one will do the job and probably last longer.

WHITE TRASH1 · Dec 25, 2009

I've ran 55 watt tractor lights paired up off of 1 switch for years. The switches are rated for 20 amps so it has a safety cushion. I also have a 15 amp fuse in the main power lead to each switch. 14 gauge wire end to end.

I would HIGHLY recoment upping the amperage on the relay to at least 40 amp if not a 100 amp so you can keep it cool. A single little plastic relay may be rated for high enough amperage but once you factor in the solderless connectors, wire quality and lengths you will be pushing that poor little relay to it's limits.

zukkev · Dec 25, 2009

WHITE TRASH said:
I've ran 55 watt tractor lights paired up off of 1 switch for years. The switches are rated for 20 amps so it has a safety cushion. I also have a 15 amp fuse in the main power lead to each switch. 14 gauge wire end to end.

I would HIGHLY recoment upping the amperage on the relay to at least 40 amp if not a 100 amp so you can keep it cool. A single little plastic relay may be rated for high enough amperage but once you factor in the solderless connectors, wire quality and lengths you will be pushing that poor little relay to it's limits.

How many tractor lights are you running off the one switch? 4??? Have you checked the amperage draw when on? If you are only drawing 15A or so, you'll be ok, but if you were to run a heavier wire, split the lights, and add relays to the system, the light will be brighter, with less load strain on the system as a whole....JMHO...

WHITE TRASH1 · Dec 25, 2009

I run 2 lights per switch. Hence my amperage safety cushion. It is all nice clean power with short wire runs fed by a 10 gauge audio grade power wire hooked to the fuse/distribution block.