One mystery that stumps many of us is the usage of fuses in electrical components residentially and commercially.  Most of the confusion surrounds the voltage, Watts, ratings and labels.  Below we will look at fuses in greater detail to offer guidelines on working out the correct fuse for every situation.

What is a Fuse?

Fuses are used in electrical appliance, automobiles, homes and businesses.  They are designed to prevent a flow of current that is higher than the value of the fuse.  One example of this is if you choose a 3A fuse; any current flow exceeding 3A will cause a surge and the fuse will “blow”.  The fuse keeps too much electricity from flowing into the equipment which would result in some type of failure such as a fire or explosion.

Any excess in current flowing through a circuit is prevented from going any further with the use of fuses.  The main purpose of fuses is to prevent melting or fire from occurring under fault conditions.  A fault condition is where a higher current value attempts to move through and the fuse disallows any extra current from flowing through.

The fuses value is dependent upon the power needed to allow the equipment to run properly.  An appliance, such as a heater, is higher powered, requiring more current and thus larger fuses with a cable that is capable of carrying it.

Molded Main Plugs

Sometimes, as within molded main plugs, the cable is molded to the plug.  The fuse is fitted within the molded plug. The fuse value is marked on the outside of the plug which makes checking the fuse very easy.  In order to check out the fuse you lever it out and check to ensure the value is the same as what is marked on the plug.

Rewireable Main Plugs

Rewireable main plugs are ones in which the user can wire on their own.  These plugs can handle a variety of currents and are marked to represent this.  Even if a cable says it can handle a 13A fuse does not mean it should be used on your appliance.  Make sure the fuse you choose matches the appliances maximum voltage not that of the cable.

Watts Verse Fuse Ratings

There is a simple calculation to determine the current amps taken by an appliance.  Divide the power in watts by the mains voltage to work out the needed amps.  For example, a 1900 watt divided by 230 voltages is equivalent to an 8.3 amp rating.  This allows you to decide between a 3A, 5A or 13A fuse.  You can obviously see that 3A and 5A will be too small for an 8.3A rating. You will need to choose a larger fuse such as a 13A.

To choose a cable with enough capacity to carry the current check the diameter of the cable.  A cable of 7.5mm or more is likely to be rated for 13A or greater.  Be careful to note that a 3A or 5A fuse should not be changed just because the cables rating is 13A however a 13A fuse should only be paired with a 13A cable not a lower rated cable.

J&P Electrical is a full service electrical equipment company.  At J&P, we supply contractors, end users and supply houses with new surplus, quality reconditioned and obsolete electrical equipment. Contact us today at for all of your bus plug, circuit breaker, switchboard, fuses, disconnects and more.