An odd light switch problem....

On my hella lights, my relay is 14V 40AMP. it came with a 250v switch. I have tried to put a more appealing switch in that was a 12V switch. Why will a 12v switch not work? I tried 3 seperate switches so i know that it cant be a bad switch. I also tried it on the lights with no relay. Why will a 12v switch, comming from a 12v battery, not power auto lights, but a 250v one will???

 

There's an explanation in my electrical basics thread (link in my signature).

Basically, you have to determine if the voltage rating of the switch is in VAC (alternating current) or VDC (voltage direct current, e.g. your car battery). The switch rated for 250V is likely rated for 250VAC...this is NOT the same as 250VDC! When you run high current through a switch, if you attempt to instanteneously interrupt the current flow, you'll produce an arc across the switch contacts. This will eventually destroy the switch contacts and/or melt the switch possibly resulting in a fire. Also, if you have sensitive equipment running off the switch, such as a stereo, the arc can destroy the equipment because you're essentially shooting a lightning bolt down the line.

To further explain, some switches are actually rated for VAC and VDC. For example, a switch may be rated for 250VAC or 12VDC. This is because VAC, unlike VDC, naturally crosses 0 volts (VAC is a sine wave), thereby naturally preventing an arc from forming. This is way the same switch can be higher rated for VAC than for VDC. If your switch is only rated for VAC, find one that is specifically rated for VDC. They can be found at most auto parts stores and online ordering sites (e.g. digikey and mouser). However, if you are running low current through the switch at 12VDC, then you can get away with using a switch rated for VAC.

Lastly, I highly do NOT recommend wiring your lights through the switch itself, always use a relay!! You could be introducing an unsafe situation. You can avoid all of the issues I mentioned above by using a relay...then you can use just about any type of switch to safely operate the relay...the relay will handle the arcing (just make sure you get a relay rated for VDC and the current your lights will be pulling). More info in my basics thread, it's worth a read...

 

Ok thanks a lot! That explained a ton just in your post but i will read your thread, electricity is like a different world to me

 

Glad I could help. You are a perfect example why I put that basics thread together....just trying to help out others since I have the electrical expertise. I get a lot of mechanical info from the site, but I noticed a gap in electronics that I could help fill. Feel free to PM me if you ever have specific questions.

 

WOW!!!!!!!!!!! i thought I would have been able to fig somthing out to help on this one! But nope i just got schooled big time and my pops used to work for the power company and he has taught me some on this matter but you got me beat!!!! Glad your around!!!!! for real