Check this switch layout out

K45

K45

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Feb 21, 2007
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Statesville
I am not to sure of this set up. Every wiring set up I have done is hooked up to a relay but this one is not like that. It looks like it is set up the switch handles the full juice and sends it to the device. Has anyone seen this? Will this work for a offroad lights and not blow something? Also 2 of the switches i want to use for my air locker. let me know what you think?

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I've burnt up a switch w 100w bulbs and no relay while my other set r working just fine w a relay.

For something like lights, its worth it to run a relay. Not only will the switch last longer, but the whole circuit will. And the performance of the lights or fans or whatever will b better if it can get a direct feed from the battery via a relay.

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It really depends on what the lights are rated at and what the switch is rated at. If the switches are rated at 15 amps, 15 amps times 12 volts gives you 180 watts, so you would be fine with 2 55 watt lights, but not two 100 watt lights. Also, the size of the wire comes into play when calculating resistance and voltage drop. If you have the specs on everything, I'm sure someone on here knows more about electrical stuff and can help you out.
 
Nailed it.
You can get switches rate to carry any amount of current you'd ever want...but mst usually don't because the switch is either too big or too expensive.

As long as you don't induce voltage drop there will no loss in performancewithout the use of a relay. But that's a big as long as
 
The main wire going in is 8AWG and the wires going out is a thick 14AWG wire. The switch is rated at 20A. I was not thinking of using anything larger than 100W lights. more than likely 55W. If i had the money i would be running LED. My air lockers only uses 5PSI to engage the locker so I think they do not draw much voltage. I am not used to this kind of set up. I have always used relays.
 
A lot of race wiring setups are only a switch and fuse/breaker. Most auto toggle switches are going to be rated 15-30 amps, so usually no need for a relay. I have aftermarket 30amp relays die occasionally, why add more modes of failure if you don't have to?
 
jeepinmatt said:
It really depends on what the lights are rated at and what the switch is rated at. If the switches are rated at 15 amps, 15 amps times 12 volts gives you 180 watts, so you would be fine with 2 55 watt lights, but not two 100 watt lights. Also, the size of the wire comes into play when calculating resistance and voltage drop. If you have the specs on everything, I'm sure someone on here knows more about electrical stuff and can help you out.
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So, to a 20 amp switch would work ok for my 100w bulbs? How does that work?

Amps x voltage = Watts and i need the answer to this equation to equal larger than whatever the load on the circuit? How would you figure wire size into this?

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Rollincoal420 said:
So, to a 20 amp switch would work ok for my 100w bulbs? How does that work?

Amps x voltage = Watts and i need the answer to this equation to equal larger than whatever the load on the circuit? How would you figure wire size into this?

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Click to expand...
A 20amp is cutting it close, but should be fine. Amps x Voltage = Watts, so the switch is 20 amps at 12volts, so it will handle 240 watts. The switch is capable of handling a MAX of 20amps +/- the accuracy of chinese manufacturing and materials.
 
jeepinmatt said:
A 20amp is cutting it close, but should be fine. Amps x Voltage = Watts, so the switch is 20 amps at 12volts, so it will handle 240 watts. The switch is capable of handling a MAX of 20amps +/- the accuracy of chinese manufacturing and materials.
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Thanks.

Now how would u decide what fudge wire to run?

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Lurch830 said:
For 20Amps, I use nothing smaller than 12awg (that's code on houses). If you think you'll be close, run 10awg (supports up to 30Amps).
These numbers are assuming copper wire.

Decent link on ampacities & voltage drops:
http://www.polarpowerinc.com/info/appendix.htm
Click to expand...


a tad more complicated than that... but your on the right path.
Wire would have to be sized or derated for length and temp. Temp will increase undr a hood and as additioanl current runs through the wire.

I am a fan of overkill, to a point, on wire size. Id probably run 8awg based on the info youve given, but I wouldnt worry about 10 either.

Again this is not advice on you situation because I dont have all the info, just my opinion based on what yove povided.
 
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