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12 VOLT TIPS AND TRICKS
Operating the BIG BERTHA 12-volt oven is quite different from using a 240-volt oven. One of the big-
gest differences is that many people are willing to 'have a go' at wiring up a 12-volt system with lim-
ited knowledge or understanding, whereas, only a qualified electrician, should ever work on 240-volt
wiring.
Below is an overview of 12-volt wiring and is why it is strongly recommended you have your power
source and wiring for the BIG BERTH Road Chef 12 Volt Oven professionally installed.
Cable requirements
There are multiple wiring gauge or size measurements making it very confusing. To name a few there
are MWG, AWG and B&S, with some going up and others going down. Then many wires are in mm that
can or may not include the plastic sheath of varying thicknesses, whereas others are in mm2 (e.g., 3mm
= 1.13mm2). Another challenge is the marketing and sales rhetoric, so even if a 12v cable says, "Rated for
50A" (e.g., this on 6mm auto cable), it does not mean that it can run a 50A load properly. It only means
that the cable will not physically deteriorate/burn under this load. But it WILL have a massive voltage
drop which is what you want to avoid.
There are countless tables that can be accessed via the internet to cross reference each wire size. The
one that we are going to concentrate on in mm2 as it shows exactly how much copper there is to carry
the current through it.
The first and most important thing you must know is how far the current needs to travel from the
power source (e.g., 'house' battery) to the BIG BERTHA oven, including the supplied power cord. That is
known as the route length. (NOTE: If power is being supplied to the 'house battery' during the process
the distance between it and the primary battery must also be considered in the route length).
While travelling from the source to destination the goal for the voltage drop to be less than 3% (DC 12v).
If your wire diameter (mm2) is too small for the route length there will be high voltage drop, putting
pressure on all elements in the system that may result in overheating and the potential for melting and/
or even fire. Our recommendation is a minimum of 6mm2 for a maximum route length of 2m. From 2m
to 5m route length, 6mm2 is acceptable however we would recommend an 8mm2 or greater, as if it is
used while driving the voltage is higher than 12v.
If your vehicle is wired incorrectly and the oven is damaged, then it will not be covered by warranty.
Your 12 Volt expert or auto electrician should be able to help you select the right size wire to get optimal
results.
NOTE: When the power supply is above 12-volts the Amps drawn by the BIG BERTHA elements will IN-
CREASE proportionately. Typically, a fully charged battery will sit at 12.6V and may sit at up to 15 Volts if
used while the battery is being charged simultaneously, like when driving.
DO NOT use a voltage step up converter with the BIG BERTHA Road Chef 12-volt Oven. Any damage
caused will not be covered by warranty
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