Need help with 12V wiring

[Gringo Loco]

Hello all, I was wondering if you guys and gals can help me with planning my 12V system. I want the simplest wiring that I can get away with; I will only be wiring 1 vent fan, and 2 12V plug sockets, and maybe some lights. I am having a hard time trying to figure out what to do and really appreciate all of your help and ideas.

Thanx again

[Gringo Loco]

Here is what I came up with. Does it look ok?

[doug hodder]

I'm no electrical wizard...but I'd replace the inline fuse to the battery with a complete cut off switch. You've already got the fuse block, a switch prior to that would allow you to completely cut power to the entire system when towing. I use those type switches in boats. Just don't think you need to pre-fuse the fuse block....but then I seldom post in electrical. Doug

[jeepr]

That will work fine. Basically everything you want to run on 12v needs a fused positive and a ground. You can also run things in series.


IE-run the positive to the positive side of a light, then from that positive to the positive on the next light, etc. Do the same with the ground. (your lights are like that in the diagram). You could do the plugs like that too, unless you plan on some serious amp draw.


To put a switch in-line, you can just break the positive line.

[Alphacarina]

I'm no electrical wizard...but I'd replace the inline fuse to the battery with a complete cut off switch. You've already got the fuse block, a switch prior to that would allow you to completely cut power to the entire system when towing

A master cut off switch is a good idea, but if the fuse block is any appreciable distance from the battery, then a fuse right near the battery positive terminal is also a good idea

If you have several feet of wire directly connected to the positive battery post and if that wire could ever come into contact with anything grounded (like the trailer frame for instance) you could have a fire withput a fuse

GREAT schematic there Gringo - You look like a pro to me!

Don

[nikwax]

If you buy a fuseblock, such as the Blue Sea unit, it comes with a fused main feed. These are very nice units (they make several models).

[brian_bp]

Ditto Don's comments.

Also, the red=positive and black=negative scheme works fine, except that it is not the common practice in trailers, where usually black=postive and white=negative. Either can work and be maintainable, as long as it is consistently applied, and preferably labeled at some appropriate points.

[Gringo Loco]

Thanks everyone, I got the two 12V plugs done today, tomorrow the vent fan.

[diverguy]

check out Joanne's link at the top of the page. it has a lot of great info and she set the standard on teardrop wireing. i modled mine exactly like hers and it has not failed me yet.

[Dale M.]

That will work fine. Basically everything you want to run on 12v needs a fused positive and a ground. You can also run things in series.


IE-run the positive to the positive side of a light, then from that positive to the positive on the next light, etc. Do the same with the ground. (your lights are like that in the diagram). You could do the plugs like that too, unless you plan on some serious amp draw.


To put a switch in-line, you can just break the positive line.

Be careful here.... IF you use series appliance(s) or lamps, voltage of lamp or appliances have to be sized accordingly.... If you are going to put two fixtures in series you need them to be 6 volt fixtures .... IF you use a 12 volt supply ... if you use 4 fixtures they need to be 3 volts each... The total of voltage drop across fixtures has to be equal to supply voltage to make lamps operate properly

I really think you mean that they should be wired in parallel... Meaning you can run hot lead (12 volt) to 2 or more fixtures and ground to other side of two or more fixtures....Such as your lights at bottom of schematic ...

[Caradoc]

Ditto Don's comments.

Also, the red=positive and black=negative scheme works fine, except that it is not the common practice in trailers, where usually black=postive and white=negative.

Really? I hope it's not. I thought it was pretty universal for black to be ground in under 120v, and sometimes green at 120+v. "Green is ground the world around", as my Dad the electritian used to say, that is until I got into lower voltage electronics, and green is not normally used.

If somebody turned that around, I'd imagine there's quite a few things hooked up backwards in trailers.

--Lance

[alexgray104]

I don't know about America, but certainly in Britain black is always ground.

Then depending on the manufacturer, red is consistently used as +ve throughout, or different colours depending on the circuit, meaning you can instantly identify which wire is which in a conduit with several wires in.

E.g

Lights: +ve Green, -ve Black
Sockets: +ve Purple, -ve Black
Fridge: +ve Brown, -ve Black
Pump: +ve Red, -ve Black
etc

[brian_bp]

Ditto Don's comments.

Also, the red=positive and black=negative scheme works fine, except that it is not the common practice in trailers, where usually black=postive and white=negative.

Really? I hope it's not. I thought it was pretty universal for black to be ground in under 120v, and sometimes green at 120+v. "Green is ground the world around", as my Dad the electritian used to say, that is until I got into lower voltage electronics, and green is not normally used.

If somebody turned that around, I'd imagine there's quite a few things hooked up backwards in trailers.

--Lance

Now here's the problem with building your own: you can do a great job, maybe better than any commercial product, but you might not match the standard practice.

My Boler and every other trailer I've seen discussed in the forum for lightweight moulded fiberglass travel trailers uses the black=positive / white=negative scheme. Okay, our eggs are a little oddball, but not in this respect... all I can suggest is going to an RV dealer with a lot full of generic white-box travel trailers, and looking at the connections. Of course, they're normally stored with no battery, so looking at the used units might be the best plan.

And yes, there are many stories of people messing stuff up in their trailer by attaching the black wire to the negative post of the battery and connecting the only other wire - white - to the positive post.

[brian_bp]

I don't know about America, but certainly in Britain black is always ground.

Then depending on the manufacturer, red is consistently used as +ve throughout, or different colours depending on the circuit, meaning you can instantly identify which wire is which in a conduit with several wires in.

E.g

Lights: +ve Green, -ve Black
Sockets: +ve Purple, -ve Black
Fridge: +ve Brown, -ve Black
Pump: +ve Red, -ve Black
etc

Great information - thanks!

In a typical North American travel trailer, colour codes are used for the vehicle lights (stop/turn/tail/clearance), but all of the interior power circuits are just black, with shared white return ("ground") wires.

The Euro trailer practice sounds like normal automotive practice worldwide. It's only RV coach wiring which does this black/white thing.

[brian_bp]

Also, the red=positive and black=negative scheme works fine, except that it is not the common practice in trailers, where usually black=postive and white=negative. Either can work and be maintainable, as long as it is consistently applied, and preferably labeled at some appropriate points.

Just to emphasize this: I'm not criticizing Gringo's choice at all - I just think it's good to be aware when doing something unusual, to keep it in mind, such as when reading procedures or recommendations from someone who may be assuming a different standard.