# 16mm2 wire maximum current (fuse)



## hhhh (Dec 2, 2005)

Hi! 

As we all know, a 600W inverter uses 50 amps when fully loaded. The thing that puzzles me that what is the maximum current that a 16 mm2 wire can take ? Various sources state it's 50 A 

Can/should I use for example 60 A mini-ANL fuse as a main fuse to the inverter without using the wire as a fuse instead...

Thanks!


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## pippin (Nov 15, 2007)

Lot of confusion there in the phrase "maximum current that a xx mm2 wire can take".

It depends on many factors.

How long the piece of wire is. 
Whether it is in free air and ventilated.
Whether the current is passed continuously.
What surface temperature can be tolerated.

For instance the 2.5mm2 cable commonly used in UK ring main wiring is supposed to be uprated to 4mm2 if it is running under a thick blanket of insulation. Nobody does though!

I suspect that your piece of cable has been rated at 50A with the various factors taken into account and that for it to "fuse" (ie burn out) would require significantly higher current to flow.


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## hhhh (Dec 2, 2005)

Hi! 

The cable is about 1.5 metres long and it'll be connected to the battery under the seat.


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## olley (May 1, 2005)

Hi standard 16mm2 battery cable is rated at about 110amps.

Olley


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## CliveMott (Mar 10, 2008)

*CABLE FUSE RATINGS*

In general terms Olley is about right.
The fuses are ONLY to protect the wiring, not the devices on the other end.
In 12 volt applications we generally use cables with a current rating well in excess of the actual current flowing in the application because the voltage drop along the cable is more important. A cable in a mains application can afford to lose say 2 or 3 volts in 230 and we will hardly notice the difference, but losing 3 volts in 12 is far too much.

As had been said it also depends on the insulation temperature rating of the cable, the thermal resistance of the insulation, if its a single cable or in a bunch, if its in free air or in a confined space or even within thermal insulation.
BUT in 12 volt applications the size of the cable is so much bigger than that required by the actual current flowing that none of the above restraints are likely to apply.

Don,t forget that fuses also work by getting hot and this means a voltage drop across the fuse. Use quality low melting point fuses and have them rated well above the normal operating currents if at all possible.
C.


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