RV FEATURE
4. INADEQUATE WIRING
12V electrical systems use DC electricity. It means the electrical current travels from the positive terminal of the battery, through the positive wires, into the appliance and back to the negative terminal of the battery through the earth wires. Depending on the size of the van, how long the wires are between the battery and the appliance, the distance can be longer than you may imagine.
As the electricity travels along the wire, resistance in the wire causes the voltage to drop. For low-power devices, this isn’ t a huge issue, but for high-power devices like fridges, light bars and inverters, this resistance can cause all manner of problems. To cope with the high power demands, as the amps rise and the distance lengthens, the wire needs to be thicker or a heavier gauge. The more copper per meter, the less resistance.
This was the wiring on a brand new caravan I saw at a show. Not the best crimping I have seen but not the worst either. I would still expect much better from a new van manufacturer.
There are charts available online that can tell an installer what gauge wire to use for any given number of amps over any given distance. This one on the Enerdrive website is an excellent example.
On this site you can see that if you need to power a device that draws, say, 10A, that is 5m away from the battery, that’ s a total wire length of 10m, requiring 2.59mm diameter cable to keep the voltage drop below 10 per cent. If the appliance is critical, say a fridge, you may want to keep the voltage drop to just three per cent. For that, you’ ll need cabling that is 3.26mm in diameter.
10A is not a lot, and any inadequate wiring is not likely to cause any serious risks, but consider if you have an inverter in your caravan. As an example, if a 2500W inverter is run at its maximum, it will pull close to 250A from your battery. That is a lot of amps, and if the wiring is unable to cope with that current, it could heat up very quickly to the point of melting the copper, potentially leading to a fire or, at least, an expensive repair bill.
/ 37