Wednesday, September 29, 2010

Avoiding certain tragedy!

In more ways than one, I seemed to avert what could have resulted in a couple of devastating consequences. 

First, and most importantly, was my realization that all it would take is a second wire to get the amperage I need from my 12 volt wall outlets.  Now, I know that you're just about on the edge of your seat, right this very moment.  So, just settle in, grab a cup o' joe and let your mind take you to amazing places.

The 12 volt wall outlet

For the life of me, I haven't been able to find out just how many amps these things are good for.  As you know, at 12 volts, a 20 amp receptacle would enable you to plug in an item worth approximately 200 watts.  Not a lot of power, there, but then again, all I really need to plug in are chargers of various sorts, perhaps a reading light, or maybe a small appliance. 

But, I still couldn't find out, on the Internet or through any company specs, what the amperage rating of these things are.  So, I punted, and ran enough wiring for 10amps.  I figured 10amps worth of power would still be fine, but after considering what 10amps will allow me, I started to second guess myself. 

This is the wire I'd need to run for 20amps of power.

That's one fat piece of 12 gauge wire. 

Definitely hard to conceal, but I am using it for the A.C. outlets powered by the inverter.  And, there are only 4 of them.  That wire is good for 20amps. 

And, this is the 10amp 16 gauge wire that I'm running for all of the lighting.

What's great about this wire is that it's red/black and enclosed in an outer sleeve. 

 I was really skeptical about running merely a standard two wire low voltage set up with all of the metallic insulation everywhere.

This black wire is what you'd find for sprinklers and outdoor low voltage lighting.  It's a two wire system, no outer sleeve, and with the positive and negative side distinguished only by a slight ridge on one of those black rubber sleeves -- a total pain in the butt to manage without the color delineation. 

 Yet, I was about to do that anyway, until I found that awesome two wire red/black stuff.

The thing about the red/black stuff is that it's marketed as "speaker wire," so it was in a different section of the electrical department.  Luckily, I stumbled upon it.  It's the same as the standard romex you'd find in home wiring, but lower amperage and stranded.  Stranded wire is important in an environment with lots of vibration.  And, flexibility is key.  

10amps is fine for all of my lighting circuits and it's very manageable wire to work with.

But, I still didnt' know the value of my 12 volt receptacles.


I was sitting in my girl's car, looking at the 12 volt accessory plug in the dash, the same way I have a million times, before.

But I noticed some writing on the front of that cap, there.

So, I flipped it up...

And, would you look at that???!!!

So, I had to rethink my 10amp wiring. 

That's a lot of wiring.  But, still not that big of a deal.  I'll just run another length of the 10amp stuff for each 12 volt accessory socket.

The electricity will find its balance and two 10amp wires connected into the same clip will work as one 20amp.  Plus, the size is still slimmer than that fat black stuff that's good for 20amps. 

I just need to double up an end like that.  I'll be using two wires instead of that one, for my addition to the 12 volt receptacles...

Add these clips...

And, there you go.  My new additions will look the same as that connection, but with two wires sticking into the back side of those clips, rather than the one wire. 

I'm glad I made the discovery of that 20amp outlet in the car. 

And, if it hadn't been for the fact that I jumped out of the back of the van, landing on this stack of wood...

twisting my ankle...

nearly breaking it...

And, waiting in the car for my girl to run in and get a bag of ice post x-rays ( which were negative for any damage),  I would have never noticed the 20amp accessory cover!  


And, twenty-four hours later, I can almost walk without a limp.  Production should be up and running tomorrow morning! 





  1. Wow...good to hear you didn't break anything from your jump!

    So a few words on the 12-volt socket thing. There are two main factors to consider: 1) how long the circuit is (in feet for the round trip) and 2) how much voltage drop is acceptable. For sensitve electronics the suggested voltage drop should be 3% or less, for resistive loads (like heaters, lights, and such) a 10% drop is suggested as a maximum. For instance, you can use 16-gauge wire for 20A service if the round trip circuit length is 16' or under and a 10% votage drop is acceptable. On the other hand a 3% drop would require 10-gauge wire for a 16' round trip.

    You can't just double up two wires as you did and get an equivalent rating to a larger wire. Because wire is circular the area increases logarithmically and the resistance (Ohms drops logarithmically). For instance a 16 gauge wire has 4 Ohms of resistance per 1000 feet but the 10-gauge wire has .1 Ohms per 1000 feet so while the #10 wire is about 2 times the diameter of the #15 wire its resistance is 40 times less.

    Where you've used your double wire in your build you should be fine since I suspect just one wire comes close to handling the load and the added second wire will help. It's not so much that this circumstance won't work, just that in general it doesn't always work to use two smaller wires in place of one larger one. And that's just for future reference...not to pick on your installation (I just wouldn't do that!).

  2. Hey Les,

    I did a little math, based on your suggestion, and it looks like I'm within .5 resistance between 12 gauge and 16 gauge. Although I probaby won't be plugging anything in that's 240 watts. Most things will be 200 or less.

    In the entertainment world, we deal with 400amp cable and A.C. power, which I know is much more efficient. But, we've always just figured our amperage needs along with the length of the runs and have either doubled or quadrupled our cable from our generators, as necessary.

    I'm going to do a "Hail Mary" on this one, and go for it. :)

    As always, I do appreciate the input!

  3. Wow I have not checked in for a couple of weeks and you have been goin hog wild on this thing. You are doin such a great job. Can't wait to see the finished product. You never cease to amaze me.

  4. Drew,

    Thanks for checking in. I'm sad to report that this project will be on hold, starting Saturday. The games will commence in June of next year. Crazy times, indeed. That's like a lifetime away,in my world.

  5. Hate to hear that cause projects like this are what I enjoy most out of life but you gotta do what you gotta do. Hope the foot is ok.

  6. tick-tock, tick-tock, tick-tock...

    But I'm glad you're having a great time in such a beautiful place.

    On my side of the world...a foot of snow last night and my bus door frozen shut :/

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