Basic relay wiring

[Cr33p3r]

I know I'm not the only one who has asked how you wire lights up using relays. So after looking around I found some good basic drawings that are very simple.

[96EXXLTinCO]

Good pics Sean!! Hands down the best way to wire lights. A little more complicated till you get the grasp of it, but far safer in the long run. I find myself using this watts to amps calculator quite a bit also to help me decide on fuse amperage for the circuit: Watts to Amps calculator (http://www.rapidtables.com/calc/electric/Watt_to_Amp_Calculator.htm) and then you want to make sure your wire size is big enough to safely handle the amperage you'll be pulling through it, for the distance it will run. Pulling more amperage through a wire than it can safely handle makes it get hot, and we know where it leads from there. Here is a wire size/amperage chart I use:

http://i1378.photobucket.com/albums/ah95/isplaytime/Auto-Wiring-Gauge-Table%20Medium_zpshtajwoem.gif

I always play it safe and go one wire size bigger. Allows for room to add on also. One more thing I'd like to share which I just recieved in the mail yesterday:

Automotive 6 way fuse block (https://www.amazon.com/OLS-PSZACCEPS051H-6-Way-Illuminated-Blade/dp/B00QMTAZ1W/ref=sr_1_1?ie=UTF8&qid=1469631568&sr=8-1&keywords=automotive+fuse+block)

by far the cheapest Ive found at $11.99 Cabela's sells basically the same thing for...............I believe $35? I will run a 8 gauge wire to the post on it straight from the battery and then pull one circuit for my 2 100w lights on top, one for my 4 55w lights on top, and one for my 2 55w driving lights, 2 4" LED pods on the back for reversing at night, and 2 more 4" LED pods that will be on the front corners angled out to light up those tight switchbacks.

[xaza]

Nice diagrams. Both show relay being wired to ignition meaning key will need to be forward to work. To work around this for a circuit you want to always have power you simply move wire for switch (yellow in diagram above) to post 30 of relay. Wire size is very important, good point Chad. When calculating length you need to add both positive and negative wires for total length. For my power inverter in the back of my XJ I had 15 ft long power wire, 15 ft ground. Total length 30 ft. Here is another link for wire sizing.
http://www.engineeringtoolbox.com/amps-wire-gauge-d_730.html
For converting watts to amps simply divide by voltage (12). Example 100 watt light divided by 12 equals 8.33 amps. If the light is 8 ft from relay which is 2 ft from battery your supply line is 10 ft. Ground run back being 8 ft you have a total length of 18 ft which shows 16g being the correct wire for this application.

[96EXXLTinCO]

Another good point cliff! Good explanation!!

[clkid]

Good stuff. Thanks for posting this information information