Electrical Wiring

Most caravans have two distinct and separate wiring systems. A 12 volt DC installation and a 240 volt AC installation.

240 Volt installations must comply with  AS 3000 and this means that caravan manufacturers have a suitable standard for such installations. Any changes to such an installation should only be undertaken by a licensed electrician. Whilst 240 volt power points in caravans look the same as those used in homes they are not. Because caravans are not earthed like a home, power points in caravans have dual pole switching.

Unfortunately there are no such standards for 12 volt installation. Few caravan manufacturers seem to properly understand voltage drop and if you mention Peukerts Law eyes glaze. Anderson plugs with so called “industry standard” 6mm wire are all too common. In fact if a salesman uses the words “industry standards” to you, in relation to 12 volt DC installations, go somewhere else, there are no such standards. He probably means “we have always done it this way and can’t be bothered changing”.

Whilst looking at caravans I continually heard “we use 6mm wire because it is rated to 50 amps”. Such a statement  confirms ignorance of appropriate wiring. The 50 amp rating just means it starts to melt at 50 amp. To use such a rating is entirely inappropriate as it doesn’t take into effect voltage drop. If talking to a caravan manufacturer request they supply you with a wiring schematic diagram and a wiring schedule. Check the schematic to ensure that all circuits are fused. This includes the Anderson Plug to the caravan battery circuit. Sounds like common sense doesn’t it but there have been numerous melted wires, melted batteries and fires to prove that this does not always happen. The schedule should show the length of each individual wire run, the current it will carry and therefore the calculated wiring size.  If no such schedule exists then it is probable that wiring sizes have just been decided by a guess and may be under size.

If the wiring to your electric brakes is not adequate voltage drop may reduce the voltage at your brakes by such an amount they may not work correctly!

The design and installation of 12 volt DC wiring systems for caravans is a specialised job. I have seen installations with under size wiring, inappropriate regulators, incorrect battery size and type to name just a few faults. These are not isolated faults. There are so many caravans on the road with faulty and or inefficient 12 volt wiring that it is evident that this is one issue that the caravan industry has a real problem with.

Whilst there are a lot of “wanna be” experts on these matters who will do more harm than good with the advice they offer there is one very authoritive and knowledgeable person. This is Collyn Rivers a scientist turned author. His books and articles on all matters relating to caravans and motor homes are a terrific resource of well researched factual advice. Do yourself a huge favour and visit his web site.

Do not rely solely on caravan manufacturers in relation to 12 volt wiring specifications. With your knowledge gained from Collyn Rivers books or articles it would be prudent for you to work with the manufacturer to determine what is required and specify this in the contract. It may be expensive or even impossible to correct faults later on.

updated 21/3/2012

goldstream, goldstream explorer, goldstream caravan, off road caravan, outback travel
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