Bushmechanix

No Kim, I needed to get power to the back of the vehicle for easy access to a variety of power applications. In the past I was running all my 12 volt accessories from the dash area and this became problematical.

Cheers

I am only using two of the wires which seem to be the same size as the 6mm. Only running 12 volt accessories.

Have never had a problem with things catching fire and I have multitude of wires powering all kinds of stuff.

Cheers

It works. Can't see why it should fail. Positive and negative wires all connected properly.

Cheers

Wire is wire. It is a flexible mix of various metals. It doesn't know the difference between 240V and 12V because there isn't any as far as wire is concerned as I understand it.

If the wire can handle the load (total watts) all will be well.

I'm with Willie, if it works and doesn't catch fire it is a success.

Having said it works is all good, .... the purpose of a fuse is to protect the cable (wire) from being overloaded. If you draw more current than the cable is rated at it will get hot. unless you have a fuse to prevent this. & in the worst possible scenario the cable could become caught up & damaged, if it shorts out & there is no fuse...... FIRE !!
I was just trying to help out. I dont add any cables to my vehicle, especially direct from the batteries, without a fuse.
PMK

Just a quick note for Jimbo,
There is a big difference between 240 Volts AC & 12 Volts DC when it comes to current draw.
PMK

Yep, fusing is a good idea

Willem
Your wiring setup sounds like mine, will get some photo's tomorrow ...A sparkies nightmare

Doug

Quite obviously there is no God/Justice, 'else you pair of Desk Jockies would have burned by now.
Why dontcha get yer arses out in the fresh air, where all is simply pure?
hahaha
(Gramps is ever vigilant: ta Gramps)
enjoy funnies,
gerhmptgggpd.

Just a quick note for PMK,

I wrote

"If the wire can handle the load (total watts) all will be well."

Current draw is measured properly in watts. The calculation is amps x volts = watts. Hence 240 volt wire rated to 5 amps is the same as 12 volt wire rated to 100 amps.

Your formula indicates that @ 12 Volts the current (watts) is higher than @ 240 volts ie; the calculation is for the load & not the cable size. At 12 volts you will need a lager cable otherwise we would all be running 1.5mm cables to our starter motors & we all know thats not the case.
PMK

Jimbo...a 240v 5a rated cable will not handle 100a at 12volt

as an example go have a look at some 10amp fuse wire for your house and then tell me if it is suitable for 100amps at 12v

Jimbo,
240V is AC and the 12V is DC. Hence the need for different wiring.
I'll leave you to figure out the rest.

Good points Phil and Nudie but I'm not sure why it is so.

The old V x A = W applies to both 12 and 240, of that I am sure. So how does thinner wire carry more watts at 240 than 12 and I'm not disputing that it does, just trying to understand.

Cheers,

Jim.

240 V 12vdc....well for one thing 240v needs better insulation

higher volts means less voltage drop....reasons why they have high voltage transmission lines.....i think lol...thnner wire only adds to inceased voltage drop and that means losses with increased temperatur gains and subsequent compounding higher amps...i = e/r.....the lower cross sectional wire diameter means increased resistance

now ...as for your wire size...a 5amp fuse is 5amps for no matter what voltage......ditto for any fuse...its a rating of current capacity before it blows or trips in circuit breaker case......

voltage does not play a part except for insulation requirements......ie a 12vdc fuse is no good on high voltage as 240v can arc across the insulation material
but a 240 volt fuse at applicable rating can be used on voltages lower than 240.... but not higher

yes volts x amps = watts

so in your 12v scenario, you need a fuse of 100a plus for proper protection....meaning bigger wire is required

Phill 12v is not neccessarliy dc...and 240v does not automatically mean AC

a lot of equipment use 12 vac in their systems...computers are one

some mining equipment i believe use 240Vdc and higher.... i know high voltage dc is used in systems for frequency drives for large motors etc

higher volts means better insulation is required...and remember, high voltage dc kills just as good as good as ac

Bloody Hell....thats too complicated mate.

I am only running a max of 12 volts DC along the wire. I am only using 2 wires inside the 15amp cable. One for positive and one for negative. The third wire inside the 15amp cable casing is dormant.
Wire length is about 5 metres. I plugged my 12volt fluoro light in to the cig socket at the end of the wires and it works brightly.

Cheers

What it all means is that don't try and get 15 amps out of the cable if it is 5 metres long.
Based upon the above formula, the maximum current available at 5 metres in length is 4.13 amps. This does not take into count additional voltage drop in the appliance leads.
So yes, the fluorescent light is OK but a fridge - with less than perfect battery status will not.

Willie it's not whether you are running 12v or 240v that matters. It's how many amps you want to run with it. That's why people with little or no electrical knowledge (like you) cause major problems like fires and even electrocution with dodgy wiring. It may take hours or days or even months to show up as faulty but if it's not done properly it will eventually show up. Personally, I wouldn't use less than 6B&S cable.

Mick

I had cause for a leccy to go into the roof of my house a while ago. He came back down with a frown on his face and later presented me with a CD of pics he took up there. Now the wiring was not my doing, but the house will have to be rewired one day. Soon! Not sure when the 'lectrics went in but the house was built in 1900. Still we haven't had any major issues and the house is earthed to industry satndards.

Yes I don't have much electrical knowledge but I use common sense and have not had an issue with electrics in vehicles except for accessory failures.

There is an overemphasis on saftety issues...something that has crept into our society over the past decade. If you are going to do stupid things with electrics then you will have problems but iof you use common sense then there shouldn't be a problem.

Cheers

willem.....at the time of doing things we, those who dont know better, fall into the same sense of false beliefs....we are not doing something stupid.....

then wham...it fails....? Duhhhhh?...has happend to me also...

but the question remains "What If"....meaning could someone have been injured or even worse a death occured by the failure?

in your problem rember Ohm didnt make up the law........

thats why we have Standards....so it keeps all and every thing safe.

Ahh Member No 1...yer worry too much!

just trying to look after you Willem

Yerrrrr. Rough and ready....LOL

Cheers

Just a bit off topic Willem, but, how many times have you or your offsider hit your elbow on that tripod thingamajig you bolted to the dash?

And secondly, I reckon those holes you put in the dash could effect the resale value when it's time to sell the old girl!

HAHAHAHAHA

G'day Muzz


My invention was carefully thought through for about 3 minutes....lol

It works extremely well and I have not hit knuckles or elbows or anything for that matter. When a mate drove the wagon on my last trip he struggled with the knuckles thing but it really is a matter of getting your brain into gear. My mate was very bemused when I went to engage Low Range as I put my arm around the tripod leg to get to the lever......lol

I considered the the dash damage and as I will not be selling the 'old girl' it doesnt matter. This is my last 4x4 unless I write it off somewhere in the sticks. Got another 10 years(if I can afford the fuel...hahaha) of 4x4-ing and may then call it quits. Anyway one can always glue the dashmat to the dash and no one will be any the wiser

Cheers

Hi Vicar

Will be running a 12v fluoro light and short bursts of 12v water pimps for food preparation and a shower. Thats all!

The wiring is fused

Cheers

>water pimps

Got to watch those illicit water sellers :)

If all you're going to run is the above items the total current draw will be 3 amps or less and the twin and earth cable you have fitted will do the job quite adequately. Use an in-line 10A fuse (ideally anti surge type) at the point the cable picks up it's power from, the battery I assume.

Mike Harding

Yeah I saw that pimps thing after I hit the button...lol

Have fitted an inline 10amp fuse to a number of my accessory connections close to the battery terminal.

Vicar.....its a combination of both voltage and amps for a kill

Willem, exactly what Mike said. I aint auto lecky, only electrician, but for runs to back of vehicle, I run a 6mm SDI, which has two sheaths, just so when traveling on rough roads, rubbing on the cable won't ruin your day...or you could run it in split conduit. Let us know how you go.

Member no.1: someones been on google looking up ohms law!!! There was talk above of voltage been the main thing, maybe we should talk resistance as well because resistance has a big part...oh, and then we haven't even raised the issue of fault current!!! Always wear rubber thongs! ;-)

me look up ohms law...nah it was drummed into me when i was young lad...many many moons ago

fault current...bloody crap...never could understand that stuff...but i know its higher... or is that lower?... the nearer you are to a transformer

Sam,

Why don't electrons travel through the middle of the wire?

Does this mean I could save weight by having a hole down the middle of the wire?

Or is a flat sheet of copper better than a wire?

Sam,
Skin Effect is only valid for high frequencies. At 50HZ or less it is irrelavent. The use of braided wire is a design consideration in High Voltage transmission lines but this has more to do with balancing electromagnetic fields than Skin Effect.

Here's a good explanation....

http://en.wikipedia.org/wiki/Skin_effect

So, R Send, no, a hollow wire won't work for DC, only for very high frequencies (radar etc) where a hollow tube IS used. It's called a Waveguide.

i stand corrected

this topic is getting to ruddy complicated....skin effect?
does that mean white skin gets burnt more than brown skin if you touch 33kv transmission lines

Struth...You guy's lost me ages ago. LOL
Goodluck Willem

Hey Footloose - some people just have to live by the rules with no room to deviate from the straight and narrow. Others - PITAs or showing off? Best to keep any non standard mods to oneself and avoid all this crap :-)

Yer my thoughts too, Footy....lol

Cheers

Hey Footyl, apologies for not contacting earlier. Our trip length was one fifth of yours; hope all is wellish as may be.
Just chanced upon your note.
Christ, I'm just so pleased that most of these experts never leave the sealed roads.
jh.

Sssssshhhhhhh you lot. This is a great giggle :)))

Hiya Jeffo, yes thanks, all as well as.
I agree with your comments.

Can you prove that it didn't cause the war in Iraq?