Wiring/lighting question

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Wiring/lighting question

Postby norm perkiss » Tue Oct 26, 2004 8:38 am

How can I find out the amp draw on the light fixtures I've purchased? I started with LEDs off the Internet, but just not enough light. "Doing over", I have since purchased Bargman dome lights. They use a 1003 bulb I think. Can I still use the #16 wire I had planned to use with the LEDs.

It seems most of you are recommending heavier gauge in general for lights. I want enough light, but I don't want to burst into flame either.

This is great site, thank you all for sharing your wisdom, insight and humor.
Thanks,
Norm
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Postby Dan » Tue Oct 26, 2004 9:20 pm

Rule of thumb:
12 gage wire will carry 20 amps - enoygh to turn on a 250 watt lamp @ 12 volts
14 gage wire will carry 15 amps - enough to turn on a 175 watt lamp @ 12 volts
16 gage wire will carry 10 amps - enough to turn on a 125 watt lamp @ 12 volts

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Wire Gage and Distance

Postby Dee Bee » Wed Oct 27, 2004 6:28 am

You also want to be aware of the distance the wire is traveling from the battery to the load (light, etc.). Over a longer distance you need a heavier wire to carry the same amps.

It is also true that thicker wires carry 12v current more efficiently. Small gage wires may be able to carry the load of a single light, but the small gage also makes the cuircuit less efficient.

I don't think you can go wrong with 12 gage wire,

Most of the 12 Volt wiring in RVs is done using 12 or 14 ga. twinlead. It's important to be sure that you use adequately sized wire to meet the amperage requirements of whatever it is that you're installing. Here's a table of wire sizes and amperage ratings that will provide some basic guidelines. This table leans a bit towards heavier wire than is absolutely necessary, but that's actually safer in the long run. Remember, always provide fuse protection of any new wiring that you install. The fuse should be sized so as to protect the wiring from meltdown. For example, don't put a 20 amp fuse on a circuit wired with 16 ga. wire.

Total
Amperage
Draw |Up to 4'|4' to 7'|7' to 10'|10' to 13'|13' to 16'|16' to 19'|19' to 22'|22' to 28'
0 - 10 16 Gauge 14 Gauge 14 Gauge 12 Gauge 12 Gauge 12 Gauge 10 Gauge 10 Gauge
10 - 20 14 Gauge 12 Gauge 12 Gauge 10 Gauge 10 Gauge 8 Gauge 8 Gauge 8 Gauge
20 - 35 12 Gauge 10 Gauge 8 Gauge 8 Gauge 6 Gauge 6 Gauge 6 Gauge 4 Gauge
35 - 50 10 Gauge 8 Gauge 8 Gauge 6 Gauge 4 Gauge 4 Gauge 4 Gauge 4 Gauge
50 - 65 8 Gauge 8 Gauge 6 Gauge 4 Gauge 4 Gauge 4 Gauge 4 Gauge 2 Gauge
65 - 85 6 Gauge 6 Gauge 4 Gauge 4 Gauge 2 Gauge 2 Gauge 2 Gauge 0 Gauge
85 - 105 6 Gauge 6 Gauge 4 Gauge 2 Gauge 2 Gauge 2 Gauge 2 Gauge 0 Gauge
105 - 125 4 Gauge 4 Gauge 4 Gauge 2 Gauge 0 Gauge 0 Gauge 0 Gauge 0 Gauge
125 - 150 2 Gauge 2 Gauge 2 Gauge 0 Gauge 0 Gauge 0 Gauge 0 Gauge 00 Gauge


See the chart at for a better visual of this infohttp://bart.ccis.com/home/mnemeth/12volt/12volta.htm

DEE[/url]
Last edited by Dee Bee on Wed Oct 27, 2004 10:13 am, edited 2 times in total.
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Wiring/lighting question

Postby norm perkiss » Wed Oct 27, 2004 8:39 am

Dan and Dee Bee,
Thank you! This helps alot.
I'm working from the Kuffell Creek plans and he used #16. Gleaning bits of info from other posts, I was starting to doubt the #16 choice.
Well I'm off to HomeDepot for a spool of #12 wire. Anybody need a slightly used roll of #16 wire?
Thanks again,
Norm
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Postby Dan » Wed Oct 27, 2004 11:05 am

Norm

Another thing to watch out for in the Kuffell Creek plans, he calls out to use drywall screws. Don't use drywall screws on woodwork. The screws are weak and usually will break if you try to back one out. Woodscrews are not that expensive.

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Postby denverd0n » Wed Oct 27, 2004 11:46 am

You really don't have to switch to 12 guage if you don't want to. With the length of runs you'd have, even in a large tear, 16 guage will be more than enough for running several lamps with 1003 bulbs.

A 1003 bulb draws less than 2 amps at 12 volts. Look at Dan's post. That means you can run 5 of these lamps on a single circuit, fed with 16 guage wire, and still be well within safe limits.
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Postby norm perkiss » Wed Oct 27, 2004 8:11 pm

Thanks Guys,
I just started to wire the interior lights. I'm only putting one light on each circuit (1 #1003 bulb each). So I guess I'll leave the #16 for those two and use #12 for the 12v outlets.
Now that you mention it, I have broken a lot of drywall screws on other projects. I'll go back and upgrade the drywall screws that I can find. I haven't buttoned anything up yet. I'm waiting for the fenders to arrive.
I appreciate all your suggestions
Thanks again,
Norm
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Postby mikeschn » Thu Oct 28, 2004 4:09 am

I used exterior grade screws... they looked like drywall screws, but I think they are decking screws.

I also used stainless steel flat head screws. They are quite nice, but a little expensive.

I don't like the extreme taper on regular wood screws. That would give them an opportunity to work themselves out with the shrinking and expansion of the wood over time. Also, they are too short.

Just my $.02

Mike...
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Postby norm perkiss » Thu Oct 28, 2004 6:53 pm

Mike.
Did you use the galvanized or the "natural wood tone". The gavanized seemed a smidge thicker.
Thanks for the 2ยข!
Norm
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Postby mikeschn » Thu Oct 28, 2004 6:55 pm

Oh definitely galvanized... if you like I can take a photo of the box they came in... (although that might get me in trouble, if they look too much like drywall screws...)

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Postby norm perkiss » Thu Nov 04, 2004 9:09 pm

Mike,
Thanks, I'm sure I found the one's you mentioned. Side by side the difference is clear. Thank for the feedback.
Norm
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