Electrify me

[jcferguson]

Enlightened,

I am nearing the part of my renovation that requires some wiring and am trying to thing ahead... a couple questions for those of you with expertise:

1 It seems that people generally use the aluminum as the ground for 12V wiring, just running the positive wire for each application (this is how my trailer was wired) - is this the best way to do it, or would it be better to run a positive and negative for each application?

2 What gauge wire should be used for the main 12V wiring: pumps, lights, fan? It looks like the old wire was 10 or 12? Does one use all the same gauge or run different gauges for different applications?

3 What gauge wire should be installed for solar cells to battery lines?

As always, thanks for sage advice.

Carlos Ferguson 1962 22' Safari

[TomW]

1) By 1967, Airstream was running positive & negative wires to each fixture, and not depending on the shell for anything. Although I do not know for certain, there is a good chance that modern-day RV electrical code requires this. If it was my '62 Safari, I would run separate negative wires because I foresee potential issues with connecting copper wire to the aluminum shell.

2) Solid 12 gauge wire should be sufficient although 10 gauge would certainly not hurt anything other than adding a tiny amount of weight. Be sure to add several circuits instead of one big one. Run the same gauge everywhere.

3) Just about anything would work here since the current level is so low. If you are really concerned, look at the gauge wire coming out of the solar cell package, and bump it down (bigger wire) a gauge or two. You may find stranded wire easier to route for this particular application.

Tom

[87MH]

Originally Posted by jcferguson

1 It seems that people generally use the aluminum as the ground for 12V wiring, just running the positive wire for each application (this is how my trailer was wired) - is this the best way to do it, or would it be better to run a positive and negative for each application?

2 What gauge wire should be used for the main 12V wiring: pumps, lights, fan? It looks like the old wire was 10 or 12? Does one use all the same gauge or run different gauges for different applications?

3 What gauge wire should be installed for solar cells to battery lines?

carlos:

I usually agree with TomW, but not in this case....the wire size really depends on the total load in amps and length of the circuit....

See this table:
http://www.powerstream.com/Wire_Size.htm

In the table you select the voltage, the length of the circuit, the total load in amperes, and the wire gauge...the program then tells you the voltage loss and the % loss.

Most lighting circuits will do OK with a 5% loss, but the solar panel and electronics would do better with a 2% or 3% line loss.

Heavier gauge wire is more difficult to work with, so I like to match the wire to the requirement.

When you start to add up the total length of the required circuit with the bends and ins and outs required to go from the "start" to the "finish" the footage adds up amazingly quickly.

I always try to err on the side of a heavier gauge rather than a lighter one due to the connection loss, vibration, humidity, heat, and possible corrossion that wire in an RV service is subjected to.

[jcferguson]

Thanks for the advice Tom and Dennis, just what I was looking for.

I was planning on using stranded wire for all my 12V wiring - is this a waste?

Carlos Ferguson

[ga501]

Hi Carlos,
Wire size charts are great for figuring ampacities, but there is something to remember.
In DC applications you have to figure 'round trip' distance...for AC, it's figured one way
distance. DC has greater losses than AC so generally speaking...for the same load in
AC, you have to upsize the wire for DC.

As a solar user/designer, I've seen some installations work well with # 10 or # 8 wire, though check your losses as compared to distance run as I've seen some cases where
# 6 was needed. And 87 MH is right...keep the losses to 2 - 3 % and you won't have a problem.
Keep us posted!!
Steve

[j54mark]

Originally Posted by jcferguson

Thanks for the advice Tom and Dennis, just what I was looking for.

I was planning on using stranded wire for all my 12V wiring - is this a waste?

Carlos Ferguson

Definitely not! Even very minor flexing will break solid wire in a surprisingly short time.

Mark

[Over59]

Stranded wire is available at your local HD in stools. If you really want to go all the way you could spring for marine stranded wire (THWN). The stuff is flexible as wet noodles and tolerates wet conditions and everything else. Since the stranded comes in all kinds of colors, pick on for your returns (negative) like yellow and you could use other colors by the amperes the circuit pulls, 6 gauge red, 8 blue, ect. In any case mark the wires so you'll know whats what when it comes time to hook up the panel. Here the colors also help as most folks cann't tell the gauge without finding the markings. If the red is on the 5 amp fuse you'll know something is wrong.

[uwe]

Carlos,
Call me if you want to know what worked for me recently. I rewired the 63 Overlander completely, not a single inch of old wire left, both 120V and 12V systems.

Best,

[RiskIt]

I just redid my 72.. all wire marine grade. Moved breaker upfront, added intellipower 80amp, 3bat. set-up (2)6's,(1)12, master switch built in. All fuses upgraded to new "Maxi" plug's. I get alot of complements on it and nothing feels better before I climb into bed to know I'm safe and will wake-up to everything working.... well most of the time

[CanoeStream]

Fer Heaven's Sake -- Sounds like you are pretty savvy in the electrical direction. It's time to look at primo how-to posts (like How to modify and install rock guard on minuet) and fully explain your project! Start a new thread -- get all the kudos and karma. It would be just the way to generate feedback and replies that might point to the best way of bringing the electronics of older trailers into this decade. There are countless questions along just this line 'out there!'

[RiskIt]

Thank you very much for the kind words. Taking a trip this wed. FL to ME and maybe when I get back. I just thought I'd sound like a fat head. The stuff I did isn't that hard, nothing on these things is that bad. You just gotta stick with it. There are so many people here who will help ya out. Many a night I thought I'd have to call someone to haul it away... but in the end, all is good.

I really like reading the posts and trying to figure out how to help someone out.

Thanks again.

O' check out the rear frame when I gutted it, so bad I had to weld in so much. That was the second worse job...... I HATE POLISHING!!!!!