12v to 240v Power Inverter

Hi,
I wouldnt use anything under a 16 square mm cable for your 3m length.
You can use an "ac" circuit breaker rated to around 16 - 20 amps, as amps are all the same with ac or dc, I use this in my truck & works great.
Another alternative is using a fuseable link with a short piece of thin wire only between the 16sq. mm cable. Your local auto elec could give you some pointers on what wire to use.

IMHO > As 240v can kill i would recommend using a circuit breaker in lieu of fusible link and an auto electrician is not an authority when it comes to 240v. Best to consult a qualified electrician for this.Wow! am I cute
If yer ain't fishing, Yer ain't livin
Richard

16 mm2 isnt that big, get your aout elec to show you some.
Put the link or breaker close as you can to the battery, then if the wire rubs through past the battery you will be saved! My circuit breaker is up close to the battery on the inner guard and doesnt get wet.

The quote ...... "as amps are all the same with ac or dc"

BULLSHI*T

And yes I am an electrician.

*A*lternating *C*urrent by its very nature alternates (or oscillates) back and forward 50 times a second (50 Hz), therefore it is 'easy' to break the arc between two current carrying contacts as they part (a switch or a circuit breaker). The arc will self extinguish because it is trying to go back and forth. Obviously this arc is harder to break the higher the voltage (the pushing force) and the higher the amps (the working energy).

*D*irect *C*urrent is called 'sticky' because it goes in one direction, and it will hold the arc a lot longer and is a lot harder to break.

Hence DC switches are bigger, have more metal, break faster and break further than comparable AC ones.

Don't assume that AC switch gear (despite its higher voltage rating) will work OK for DC. Sometimes it will, sometimes it won't. In 'no load' situation they will normally be fine, but under moderate or heavy DC load they can fail (ie melt and/or weld itself together).

Put a DC style fuse on the battery lead side ****AND**** put a 240V AC style circuit breaker in the inverter 'out' side if you are concerned about safety.

hi kev,16mm is the what i would use over that distance as i think you have a 60 amp fuse on your inverter or they might of put 2x30 amp fuses on it.the reason for a fuse is not only to protect your inverter but to have a fuse blow so as your wires are protected. a 40 watt light will pull 5amps,a small TV is 7amps.your battery is im guessing 90ah therefore if you somehow manage to load your inverter fully with appliances. 10mm cable is more than over loaded.so yes as you say your only going to use lights/radio etc 6-10mm is capable of handling the job, but it is not sufficent if for some reason you are pulling max current 90amps,so we need to make sure the fuse will blow first. cheers

Gday
Went around oz with an Inverter under the rear seat to power the lights in the van (and Telly).
It is not advisable to lengthern the incoming leads, because voltage drop infront of the inverter will shut it down prematurely
Similarly, a fuseable link will cause VD and thats why the factory leads dont have one.
I got around this by putting the second battery besides the cargo draws behind the wheelarch, and then mounted the leads straight to the battery.
If you cant mount the inverter close enough to the battery, then you will have to lengthern the incoming leads.
Using larger good quality wire should suffice, im not sure how big but there is a formula on Georges Landcruiser site if you search the web for 80 series.
The best advice i can give you is to brace any cabling you run securely, using cable ties etc and beware of/insulate any rub points/sharp corners.
If you wish to put a safety fuse inline, use two 80a fusable links (used for the alt of the 80) These will blow if a short occurs in the main feeder, and the inverter will have its own protection for smaller shorts.
Andrew
wheredayathinkwer mike?

ROFL!!! :)

Use the relationship P = V x I where P = power in watts, V = voltage in volts and I = current in amps. For Pin divide rating (output) by efficiency (usually around 90%). So 500w out at 240v = 2 amps (or thereabouts), Pin = 500/.9 = 556, therefore input current = 556/12 = 46 amps, use cable commensurate with this current. 16 mmsq is good for about 60 amps so seems a little heavy, 10 mmsq over this short distance should be OK.

Jaycar sell resettable high current DC cirtcuit breakers that look to be waterproof - and lower voltage drop than fuses.