Do it yourself Led lighting help!?

I agree with Gary in that the fuses are not blowing from over voltage. If they blow that quick you are introducing a direct short after the switch, if it blows before you switch them on then the issue is before the switch. Use a continuity tester and disconnect each strips leads from the power source and from the ground leaving them in place touch one probe to a clean metal ground and the other to the hot lead.. One or maybe two strips will tone {continuity setting will have a sound when the probes touch each other and in this you will find the hot lead that is touching ground and shorting out. My guess is you might have gotten a wires pinched in a screw or under the strip and it is touching ground. The point of contact will be marred with a burn mark more than likely. How many lights and at what wattage each are they? I'm sure you did a load calculation to insure the load did not exceed 20amps prior to installation and the reason I did not suggest this first. Rule of thumb do not exceed 80% of the allowable load. Therefore a 10amp circuit should be at 8amps or less, a 20amp does not exceed 16amps etc... If you find each strip clear of shorts then test your main lead from the switch to ground like the strips. Attaching the ground or negative lead to the frame or similar clean point is no different from attaching it to the battery lead. The problem is usually the point of contact is not clean and making good contact and the circuit is stressed to make a complete circuit this will decrease the voltage which inversely raises the amperage or the work being done {amperage and wattage are considered work done on a circuit}. It is preferred to attach your grounds to the Chaise and not all on one terminal as this causes undo heat build up in one location. I'll keep an eye on this if you have any questions or additional posts.

PS use ohm's law when calculating the load:

E=I (X) R where E=Voltage {12Volts} I = Amperage and R = resistance..............

From this the power factor formula {which you would use in load calcs} is derived from:

P = I (X) E {remember PIE} where P=Wattage {of each lamps or strip} I = amps and E=voltage

{Example} LED strip is 20watts {20-1watt lamps} attached to a 12volt supply using the above:

20W=12V X ?A or ?A= 20W/12v {20 divided by 12} the calculated load in amps of the strip=1.67amps and you can attach 8 strips on a 20 amp circuit before the 80% rule of 16amps.

One last thought 12volts only goes 20' before the wire size needs to increase. This too raises the resistance, lowers the voltage {known as voltage drop} and increases the amount of wrk needed to complete the circuit. A 20amp circuit regardless of its voltage requires a #12 AWG {american wire Gauge} wire size, after 20 foot it should increase to #10AWG. It is easy to exceed the length when serpeniening through holes and around areas to get from point A to point B. Check to assure this is not a factor as well.

The problem is the way you have grounded the lights. The circuit is apparently shorting to the car's frame instead of making a complete circuit to the battery. Are there three wires or two in your kit? If there are three, I suspect you have the neutral wire (usually a white or gray one) grounded to the chassis instead of returning the neutral to the battery and grounding the ground wire (typically a green wire). The black, red, or yellow wire should be the hot wire, and should run from the positive battery terminal to the switch, and from the switch to the lights.

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