aux reverse lights

[7echo]

I am planning to install some aux reverse lights. These have the typical 12v/55watt lamps. The wires on the pigtail coming off the light fixtures are 16ga stranded I ~think~...

I plan to use the Hella diagram here...

http://4runners.org/image/hella500/hella_500_auxfusebox.jpg

I will likely mount the aux fuse box under the rear passenger seat, like robb1887 did. Seems like a good central location and out of the elements.

I need help with the wire sizes. I tried using a few online calcs but they came out different. I am sure some of you guys will know the answers.

What size wire from the battery to the fuse box?
What size wire to the aux reverse lights?

 

[habanero]

My calculations for bat to the block I used under the seat were - gauge and I think I used 14 gauge for the aux reverse though mine are wired slightly different to run automatically with the reverse lights, on demand, and not at all.
All I can guarantee on my wiring is that I'm no electrician.

Edit: Will be rethinking my Blue Sea #5029 100amp max block possibly, though not planning to use that much stuff with it. Thank you [MENTION=116745]jeremyc74[/MENTION]

 

[jeremyc74]

For 55w lights you're looking at under 5 amps each, so 16 gauge is fine if you're running a wire all the way back for each one. If the two are sharing a common wire I'd bump up to 14 at least.

16 would handle 10 amps, but you're above 80% of its capacity at that point, and the general rule is to bump up. Also, since we're talking about a 12V environment you want to minimize voltage drop to the lights by using the larger wire.

Generally speaking:
14 is good for 15 amps
12 is good for 20
10 - 30A
8 - 40-50A (at this point you need to know a little more about the insulation to be exact)

So for your fuse box wire, you either need to know what your total load is, or you can just use one large enough that it can handle everything the fuse box can.

What's the max rating on the aux fuse box?

Also, if you're looking online, a lot of stuff dealing with automotive wiring will be coming from car audio website, and they'll tend to recommend larger wire sizes for a given load, because amplifiers are capable of pulling short term currents that are way higher than their continuous draw. Those numbers will be overkill for a simple load like a light.

 

[TheDurk]

Nothing wrong with any of the above, but I do my lighting circuits in 12 ga. Electrically it is overkill in many cases, but the physical resistance and strength of the wire and its insulation is far greater than 14 ga. Also, lighting circuits are exposed to weather and often transit the engine bay, and if corrosion gets started at a connection (yeah, I know, do it right and it won't happen), the 12 ga. will resist for far longer before it fails.

I save the 14 ga. for inside out-of-the-weather low-amp runs and I won't use 16 ga. for anything. I like copper.

 

[7echo]

"What's the max rating on the aux fuse box?"
100 amps. It is a Blue Sea 5025...
https://www.bluesea.com/products/5025/ST_Blade_Fuse_Block_-_6_Circuits_with_Negative_Bus_and_Cover

The lights have Deutsch plugs with 16 gauge wires. They are sealed well. I guess I can run 12 ga back there and tie into the 16 gauge on one light and jump off that one with 12 gauge to the light on the other side.

Thanks for the replies.

 

[bmodo16]

I've been eyeing something like these lights and throw into my rear bumper I'm about to build.

2X 16W CREE Square Flush Mount Flood Beam LED Work Light Off Road Fog 4WD Truck | eBay