Final answer:
Electrical appliances must have at least two connections, live/hot and neutral, and often a third, the ground/earth connection for safety. A toaster, frying pan, and lamp together draw more current than a 15-A fuse can handle, causing it to blow. Safety regulations recommend using only up to 80% of the breaker current capacity.
Step-by-step explanation:
Most electrical appliances need at least two connections for operation - a live/hot wire and a neutral wire, but many also have a third, which is the ground/earth connection. The live/hot wire supplies the voltage and current needed to operate the appliance, while the neutral wire provides a return path for the current. The ground/earth connection is a safety feature that provides a low-resistance path directly to the earth, making the appliance safe to touch and protecting against electrical faults.
To calculate the current drawn by each device, you can use the power formula P = IV, where P is power in watts, I is current in amperes, and V is voltage. For instance, an 1800-W toaster would draw 15 amperes of current on a 120-volt circuit (I = P/V, so I = 1800 W / 120 V = 15 A). For the 1400-W electric frying pan, the current would be 11.67 A, and for a 75-W lamp, it would be 0.625 A. Adding these up, the total current drawn by all three devices would be 27.295 A, which would exceed the 15-A fuse rating. Therefore, this combination of appliances would indeed blow the 15-A fuse.
Regarding continuous use, safety regulations recommend using only up to 80% of the breaker current capacity to prevent overloading and potential hazards, aligning with why many heating appliances have power ratings that top out around 1500 W.