How do you calcolare electrical power?

Power (watt) equivale un voltage (volt) multiplied da current (amps): P = V × I. Ad esempio, un device drawing 10 amps da un 120-volt outlet uses 1,200 watt (120 × 10 = 1,200W).

How many watt puo un 15-amp circuit handle?

A 15-amp circuit at 120V puo theoretically handle 1,800 watt (15 × 120). However, electrical codes recommend not exceeding 80% per continuous loads, so practical limit e 1,440 watt.

Cos'e il difference tra watt e amps?

Watt misurare power (rate di energy usare), while amps misurare current (rate di electron flow). They're related da voltage: Watt = Volt × Amps. A 1,200-watt device draws 10 amps at 120 volt, but only 5 amps at 240 volt.

Electrical Power Explained

Watt, Volt, e Amps

Understand Electrical Power

A 60-watt light bulb, un 15-amp circuit breaker, e un 120-volt outlet—how do these relate? Comprendere il relationship tra power (watt), voltage (volt), e current (amps) e fundamental un working con electrical systems safely e effectively.

Comprendere Each Quantity

Voltage (V) - Electrical Pressure

Voltage e il "pressure" that pushes electrons through un circuit. Like water pressure in un pipe.

US household: 120V (standard), 240V (heavy appliances)
Europe: 230V
Batteries: 1.5V, 9V, 12V typical

Current (I, measured in Amps) - Flow Rate

Current e il amount di electrons flowing per secondo. Like water flow rate.

Small electronics: milliamps (mA)
Light bulbs: 0.5-1A
Appliances: 5-20A
Electric car charger: 30-50A

Power (P, measured in Watt) - Work Rate

Power e il rate di energy transfer—how much work e being done per secondo.

LED bulb: 9-15W
Laptop: 45-100W
Microwave: 700-1,200W
Electric heater: 1,000-2,000W

Power Calculations

Finding Power

P = V × I

Esempio: Hair dryer on 120V drawing 12A

P = 120 × 12 = 1,440W

Finding Current

I = P / V

Esempio: How much current does un 1,800W appliance draw on 120V?

I = 1,800 / 120 = 15A

Finding Voltage

V = P / I

Esempio: A 60W device draws 5A. What voltage?

V = 60 / 5 = 12V

Converti Power Unita

Circuit Capacity

Knowing power helps ensure you don't overload circuits:

Circuit Breaker	Voltage	Max Power (at 80%)
15A	120V	1,440W
20A	120V	1,920W
30A	240V	5,760W
50A	240V	9,600W

Il 80% rule: Don't continuously load circuits beyond 80% di their rating.

AC vs DC Power

DC (Direct Current)

Batteries, solar panels, electronics. Power e simply V × I.

AC (Alternating Current)

Household outlets. Power calculations sono more complex due un phase relationships:

Apparent power (VA): V × I
Real power (W): V × I × power factor
Power factor: 0 un 1 (1 per resistive loads like heaters)

For resistive loads (heaters, incandescent bulbs), power factor ≈ 1, so W ≈ VA.

Comuni Appliance Power

Appliance	Watt	Amps (at 120V)
LED light bulb	9-15	0.08-0.13
Laptop	45-100	0.4-0.8
TV (LED, 55")	80-120	0.7-1.0
Refrigerator	100-400	0.8-3.3
Vacuum cleaner	500-1,500	4-12.5
Microwave	700-1,200	6-10
Hair dryer	1,000-1,800	8-15
Space heater	1,000-1,500	8-12.5
Electric oven	2,000-5,000	17-42 (240V)

Conclusione

Electrical power (watt) equivale un voltage times current (W = V × I). Comprendere this relationship helps you calcolare circuit loads, choose appropriate wiring, e avoid overloading circuits. Most US household circuits sono 15A o 20A at 120V, limiting continuous loads un circa 1,440W o 1,920W respectively. Always respect these limits per safety.