Hard wiring fused inverters, Do I need another wire on the Positive Wire?

That heading should read Hard wiring fused inverter, do I need another fuse on the positive wire. Sorry
Matt

My shortest reply ever... No

I'd be putting a protective fuse at the source (battery), just to protect the line (as others have said) - and the current would be around 3A to 4A no ?

Hi All,
Thanks for your snappy replies. Just had a look on the Projecta web site. Have a look at page 10 Inverter Hard wired So I guess that I need a 100amp circuit breake of fuse. Cheers
Matt

To clear it all up.
I have done a bit more reading of the website. I didnt get instructions with the inverter so this is what I am doing. I want to mount the inverter on the side of my center console. I have 4m of 32mm2 wire(only need about 3.2m. I have now read that I need a 100amp fuse or circuit breaker and I need to double insulate the wire. Thanks for your snappy replies and help.
Matt

And just to un-clear it... :)

1 - you do need a fuse/breaker at the battery.
2 - I assume you mean 32/0.2mm cable or 1mmSQ. CSA?

For the cable... it depends what type you have; Tri Rated 1mm Switchgear cable to BS6231 is rated at 17A for single cores running in free air with a temp. rise of less than 35C. However 32/0.2 2491X 1mm equipment wire is rated to 10A and 32/02 Equipment Wire to BS4808 is only rated to 6A at 70C. Simple really, isn't it? :)

Your 600W inverter will draw about 55A at maximum power which far exceeds any of the above ratings for 32/0.2! We'll ignore it's surge rating as this won't really matter as far as the cable is concerned.

Using the calculator here:
Voltage drop calculator
your 3.2m of 32/0.2 is going to drop around 3V at 55A and apart from the fact that your inverter won't like that the cable will also be dissipating about 165W of power which, may well cause the insulation to melt.

I suggest you go for something like 6mmSQ CSA equipment wire and a fuse of about 70A at the battery - get a quality fuse holder and good lugs to connect at both ends. I also suggest covering the cables with clear PVC tube. NB. Ensure you use an earth return cable direct to the battery negative too.

Mike Harding

1. You ALWAYS need a fuse at the Battery (or other pwer source).

2. The fuse rating must be LESS than the current carrying capacity of the THINNEST wiring fed anywhere by that fuse.