offroad Lamp/light question...

[VTSTOMPER]

I have the HUMMER factory light bar, with the stock 4 off road lights attached to it. I am planning on adding 2 more of the stock off road lights to the bar, to give me 6 in all. There is enough room, and they connect light to light, in a series.

My question is, will the stock wiring harness handle the load increase?

[ree]

If you know the wattage of all the lamps, then here's what to do. Sum the wattage, divide by ~10 to be conservative. This is the approximate amperage draw of all lamps (I have nto clue what the real formula with units is...I=PV or something like that...just that this is a rule of thumb).

Multiple this by 1.5 (150%) to arrive at a recommended peak amperage rating.

Then look at this wire sizing chart to find the best wire to accomodate your wattage needs.

For example, let's say you have 6 65W lamps. That's 390W. Divide by 10, multiple by 1.5 (or divide by 6 2/3). You get 58.5 amps. According to chart, you should use 10ga wire. You can probably get by with 12ga wire, but 10ga is safer.

I'm not sure what stock wattage and wiring sizes are, but if you find the existing wiring is too small a guage, then you probably shoould wire a new harness on a separate relay just to be safe.

[ree]

Rodster, your're right about eh RMS watts. The 12volt.com is largely audio/security system buffs and most of the discussion seems to be with speaker systems.

But the gauge-amperage chart is good.

In my online research, I've seen umpteen references to the divide by 10 (or 12 depending on who you talk to) and add 50% for peak/spike demands at device startup as the "formula" for miscellaneous DC accessory wiring. This is pretty close to their RMS-amp table, but not exactly.

I take the approach, error on the side of the heavier gauge if you can bear the cost. It's safer.

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VTSTOMPER:
came back with this:

"no, they work perfectly, they brighten up the road, and all bulbs work, even comes with the rocker light switches and wiring."

IMO if you leave them on they will melt the wires. </div></BLOCKQUOTE>

Or hopefully, blow the fuse(s) instead. The wire rating should exceed the fuse rating.

[VTSTOMPER]

ok, these are #14. So I am kinda leary of tossing another set on. I might just run another circuit, so I will need another switch and all that jazz. what a pita...I would like to up the guage wires, and remain with one switch, but I hate hacking up factory items.

[VTSTOMPER]

Thanks Ed, I just got a set of used ones for 40 beans!

[rodster]

VT -- I emailed the chart in Word format and then tried a screen capture and surprise, surprise, it worked.

Thanks to LasVegas for sharing this.

[Ed G.]

VTSTOMPER are you looking to buy 2 or do you already have them? I have 2 for sale, make me an offer if you're interested.

Ed

[VTSTOMPER]

ok, I will check them out and let you know the size! thanks man!

[rodster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VTSTOMPER:
"you smell that?" </div></BLOCKQUOTE>

Too funny!

If nobody else has a good answer, I have a chart that shows how far you can run a given guage wire at different loads. If you know the wire size of the harness and the length of the run, it should be easy enough to figure out if it'll handle the load.

[rodster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VTSTOMPER:
My question is, will the stock wiring harness handle the load increase? </div></BLOCKQUOTE>

You should be okay unless it melts. Then you're not okay.

Helpful, huh?

[VTSTOMPER]

yep

6 inch, 12 volt, 55-watt

Going from 4 to 6! I think that the distance is about 6+/- feet

[rodster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ree:
But the gauge-amperage chart is good.
</div></BLOCKQUOTE>

Distance is a factor, too, yes?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I take the approach, error on the side of the heavier gauge if you can bear the cost. It's safer. </div></BLOCKQUOTE>

I hear that. I had a definite case of overkill going when I wired my roof lights.

Hopefully VT won't have to pull new wires to drive his extra two lights.

[VTSTOMPER]

"you smell that?"

[VTSTOMPER]

I have the HUMMER factory light bar, with the stock 4 off road lights attached to it. I am planning on adding 2 more of the stock off road lights to the bar, to give me 6 in all. There is enough room, and they connect light to light, in a series.

My question is, will the stock wiring harness handle the load increase?

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
VT -- I emailed the chart in Word format and then tried a screen capture and surprise, surprise, it worked.

Thanks to LasVegas for sharing this.

</div></BLOCKQUOTE>

FYI, in planning an upcoming I ran across a nice wire guage estimation tool. Plug in run length, current, defaults to 12V and 3% voltage drop. Select Calculate and it gives the the wire gauge you need.

Direct Link: Ancor's Wire Calculator (Java applet)
Indirect Link: go to http://www.ancorproducts.com/ then under "Technical Information" select "Wire Calculator"

It's pretty consistent with the chart rodster posted. It's a tiny bit more liberal in allowing smaller guage wires, suggesting that rodster's chart is allowing for lower % voltage drop.

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ree:
But the gauge-amperage chart is good.
</div></BLOCKQUOTE>

Distance is a factor, too, yes?
</div></BLOCKQUOTE>
Yes. Distance is a factor. I think I've got a ref to a chart. Yes. Here it is.

Amps-Wire Gauge w/Distance for 12V DC circuit.

It's fine for circuits under 70A and only starts at 15ft. I think most circuits on an H2 are going to be under 25ft.

Unfortunately, I can't find a chart that starts at 1' and runs up to 25ft.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I take the approach, error on the side of the heavier gauge if you can bear the cost. It's safer. </div></BLOCKQUOTE>

I hear that. I had a definite case of overkill going when I wired my roof lights.

Hopefully VT won't have to pull new wires to drive his extra two lights. </div></BLOCKQUOTE>
Yes. This just burns away the time for someone like me who knows just enough to decide to do it on his own, but not enough that he doesn't have to research it for hours before pulling the trigger.

[VTSTOMPER]

kewl man!

Thank you very much for sending it my way!

[rodster]

Any idea what size the wire(s) is/are?

And just 'cause I'm curious, where are you getting the 12v? Using a relay? Where's the switch?

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
VT -- I emailed the chart in Word format and then tried a screen capture and surprise, surprise, it worked.

Thanks to LasVegas for sharing this

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VTSTOMPER:
kewl man!

Thank you very much for sending it my way! </div></BLOCKQUOTE>
</div></BLOCKQUOTE>

Rodster,
Yes thanks.

Now if you could figure out the #16 and #18 gauge lengths for the lower power circuits that'd be great.

Still worth printing and tossing in the electrical toolbox.