Upgrading existing circuits is very often necessary when installing new shower units, cookers, ovens
and hobs. Some new domestic appliances will require to be installed using heavier cable than your
existing cable. If a manufacturer states that their oven for example needs to be installed on 10mm
cable and your existing circuit is run on 6mm cable then your existing circuit will need to be changed
from 6mm to 10mm cable in order to accommodate the new appliance.
The difference in cable size may not seem significant but the manufacturers specifications are there
to be followed and any deviation may result in appliance failure, a void warranty or a more
catastrophic event like a fire. Any upgrade in cable size will almost certainly result in the need to
replace the existing circuit breaker as well and possibly (depending on the age of your particular
electrical set up) introduce an RCD unit if one does not already exist.
Domestic appliances that have high power consumption values have to be installed by a suitably
qualified and competent person in order to ensure the integrity and safety of the installation. The
kilowatt rating of any new appliance will determine how the circuit will be set up and this should
only be carried out by a qualified and competent person.