Problem w/ 16 g wiring for tail/turn/stop + marker lights?

[misterW]

I recently ran wires underneath my trailer for the LED turn/stop/tails and the front and back marker lights. The amps drawn by the LEDs I'm sure are miniscule (these LEDs right here: http://abctrailerparts.com/ledtrailerlights.html), probably less than an amp each, and I'm sure the wattage of the marker lights couldn't be more than around 5-10 watts (5 or 10 watts/12 volts=not much).... so 16 gauge wire seemed to give me a pretty big safety margin.

For what its worth, initial tests with a battery show everything working fine.

However, now I am starting to wonder. The wires run the length of the trailer (12ft trailer + tongue) to the tail lights, then come all the way back to the front. So, a good 30 feet.

Do you think this is a problem?

[Steve_Cox]

Nope!

[BPFox]

OK, I gotta ask. Why did you run the wires twice?

[Larwyn]

Your wire is plenty big enough for the job.

I think the mention of "all the way back to the front" was probably in reference to the current path from the battery, through the light, and back to the battery.

[misterW]

^^ Larwyn is correct; I just meant that the entire circuit path (including my ground wire that went back to the battery) was 30 feet. I had decided that I would send a ground wire from the lights back to a ground bar at the front of the trailer, rather than send my grounds to various points on the frame.

I had gotten concerned because the wiring distance chart at the bottom of page 1 of this sticky (http://www.tnttt.com/gallery/image.php?image_id=35343). Seems like even the capacity of the 14 gauge is really tapering out after 30 feet.

[Larwyn]

^^ Larwyn is correct; I just meant that the entire circuit path (including my ground wire that went back to the battery) was 30 feet. I had decided that I would send a ground wire from the lights back to a ground bar at the front of the trailer, rather than send my grounds to various points on the frame.

I had gotten concerned because the wiring distance chart at the bottom of page 1 of this sticky (http://www.tnttt.com/gallery/image.php?image_id=35343). Seems like even the capacity of the 14 gauge is really tapering out after 30 feet.

I've never seen that chart before. It's got lots of purty colors and stuff. But I think I will stick with the ampacity charts that I have been using for years now. I'm not sure what the source of that chart is but if I am reading it right, I do not see much useful information there.

Here's a link to a more realistic ampacity chart...
http://wiki.xtronics.com/index.php/Wire-Gauge_Ampacity

[misterW]

Thanks for the input, guys --good to hear the voice of experience.

Now, as far as that chart, and in general, how much do you take the distance of the circuit into account? Or do you pretty much just go by the maximum ampacity? I ask because I run into the same issue with my lighting circuit -- 6 amps total current, so 14 gauge seems like it would be fine, but by the time I go from the battery to one light, to the next, to the next, and back to the battery, I'm looking at that chart wondering if I shouldnt be using 12 gauge.

Just curious as to your general approach.

[zipz71]

If I read your post correctly You are running all of your lights on one circuit.
If you split your electrical into more than one circuit using a fuse block and terminal strip then you should be able to run everything from there using 16 gauge to your lights. Then from the fuse block and terminal strip to the battery terminals you could run 12 gauge or larger depending on your needs
The wire gauge tables shown here might help you.

http://www.rbeelectronics.com/wtable.htm

[Larwyn]

The 14 gauge copper wire is about 2.5 ohms per thousand feet. You will not want more than about 5% loss on a lighting circuit. Less is better.

Thirty feet of fourteen gauge wire supplying 6 amps would drop about .45 volts or 4% of the 12 volts.

That is acceptable and you would probably never have a problem with it. I ran 12 gauge, mainly because I had 12 gauge, and would have had to buy wire to run anything smaller or larger.

My battery cables are 6 gauge welding cable for the same reason. I had the welding cable and it is as limp as a wet noodle, it just makes good battery cables for this application.

I generally use larger wire than what the charts would call for. I'm not building hang gliders and at the length used in a TD the there is not that much difference in cost/weight.

[GreatPumpkin]

I'm not an electrician, but 16G should be more than sufficient for the application of wiring a Teardrop. The following link shows 18G for 4 or 5 wire applications, and 16G for 6 or 7 wire applications (for the marker and turn/brake lights). http://www.etrailer.com/faq-wiring.aspx

As a point of reference, many TD builders start with a Harbor Freight trailer. I don't know the wire gauge they originally come with, but the replacement wiring kits (4 wire) they sell are only 22G
I'm planning on running either 16G or 14G (2-conductor) simply because I have a large spool of both. Each fixture will have power and a ground wire and run to a 7 way connector at the tongue.

[Shadow Catcher]

One question, do you plan on charging the trailer battery from the TV if so you will need 10 ga wires (ground and power) from the TV battery to the trailer.

[GreatPumpkin]

One question, do you plan on charging the trailer battery from the TV if so you will need 10 ga wires (ground and power) from the TV battery to the trailer.

Yes. I plan on charging the battery from the TV. However, I'll probably only run 12g for a couple reasons.
1) I'm planning on locating the battery on the tongue, so it will be a very short run to the TV's 7-way connector.
2) My TV is a Dodge Ram with a factory tow wire harness already installed. IIRC the factory wire size for those two functions is 12g so it wouldn't be any added benefit to up size the wire for the short distance the trailer side will run.
Now if someone were wiring the TV from scratch, I would completely agree with you, and would probably even recommend going with 8g for the charging wire.