# 12v Heater 120w



## teemyob (Nov 22, 2005)

10 amp cable?

TM


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## raynipper (Aug 4, 2008)

Yep, at least.

Ray.


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## pippin (Nov 15, 2007)

..... and a 3A fuse in case you accidentally plug into mains!


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## listerdiesel (Aug 3, 2012)

2.5sq mm or go to 4sq mm if a long run (greater than a couple of metres)

Peter


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## pippin (Nov 15, 2007)

Sorry for being flippant.

However - do consider whether the plug/socket will handle 10A on a continuous basis.

You want the heat to come out of the heater - not out of a burning plug/skt.


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## gaspode (May 9, 2005)

Peter is right.

I'd recommend 2.5sq mm as an absolute minimum, 4.0sq mm would be better, reduce volt drop and prevent the cable getting warm. If the heater is to be used for extended periods I'd avoid the usual "cigar lighter" type sockets too.


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## pippin (Nov 15, 2007)

By the way - there is no such stuff as "10A cable", as shown by the recommendations to use cable of a certain (minimum) cross section.

It's all down to the resistance of the cable, the current passing and the acceptable/safe rise in temperature of the cable in passing that current.

Again, it's all down to our good old friend Herr Ohm.

Current, voltage, resistance and watts are all interdependent.

It is fairly easy to work out the watts that will be dissipated in a length of cable just by knowing its resistance per metre and the current being passed.


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## teemyob (Nov 22, 2005)

Thanks.

I went for 3sq mm / 27 amp.

TM


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## listerdiesel (Aug 3, 2012)

You can get 20A rated, Germany-made cigar lighter sockets, they are nicely made and sell on fleabay.

You can also get matching plugs but from a different seller.

The basic stuff is only good for 3-5A, more on short-term loading.

Our Mobicool coolbox plug got VERY warm in France, we had to change it for a better quality item.

Peter


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## teemyob (Nov 22, 2005)

I have used the OHMS table for years, and forget it every time I do.

Trev


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## pippin (Nov 15, 2007)

As long as you remember that On Her Majesty's Service is not OHMS Law!


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