What is the difference between AC and DC?

The easiest way to tell is by checking the power source. Wall outlets almost always provide AC power. For individual devices, look for a label or power adaptor. The symbol for DC is a solid line with a dashed line below it (⎯ / – – -), while the symbol for AC is a wavy line (~).

• Is it a wall outlet? It’s AC
• Is it a battery? It’s DC
• Is it a USB port? It’s DC
• Is it a car charger socket? It’s DC

Look for the “INPUT” and “OUTPUT” information. On most adaptors, this text is moulded into the plastic or printed in small white text. Check all sides of the adaptor – manufacturers often hide this information on the side that faces the wall.

• ~ means AC
• ⎯ over – – – means DC
• V stands for Volts
• A stands for Amps
• W stands for Watts

1. Grab your phone charger right now
2. Find the small text on the plug (you might need good lighting)
3. Look for the “INPUT” line – you’ll see “100-240V~” showing it takes AC power from your wall
4. Now look for the “OUTPUT” line – you’ll see something like “5V ⎯ 2A” showing it delivers DC power to your phone

Self-Check Method: If the device has a large, heavy power adaptor (a “wall wart” or “brick”), it’s almost certainly a DC device that needs to convert the AC from the wall. No brick? It’s probably running on AC directly.

Plugging a device into the wrong type of current can permanently damage it. An AC device may not work at all on DC power, while a DC device connected directly to an AC outlet without a converter will likely burn out its internal components within seconds due to the alternating current and higher voltage.

Problem: I plugged my Australian laptop (240V AC) into a US outlet (110V AC)
Solution: Most modern laptop chargers are dual-voltage (check for “INPUT: 100-240V~”). You likely only need a simple plug adaptor. If it’s not dual-voltage, the laptop may charge slowly or not at all, but won’t be damaged.

Problem: I tried to wire a 12V DC LED strip directly to a 240V AC wall outlet
Solution: Disconnect immediately if it hasn’t already failed. You need a proper LED driver (AC-to-DC converter) rated for your LED’s voltage and wattage. The LED strip is likely damaged if exposed to AC mains power.

Problem: My device says “DC IN” but I only have access to wall power
Solution: You need the correct power adaptor. Match three things: output voltage (V), minimum amperage (A), and plug polarity (+ inside or outside).

1. Always match the current type (AC/DC)
2. Always match the voltage (V) – a 10% variance is usually safe
3. Ensure the power source can supply at least the required amperage (A)
4. When travelling internationally, check if your devices are dual-voltage before buying converters

In a typical Australian home, the wall outlets provide 230-240V AC power. This powers large appliances like fridges and washing machines directly. However, most of your electronics (TV, computer, smart speakers) use an adaptor to convert that AC power to DC internally.

Best for Wall Outlets: AC
Why: It’s efficient for energy companies to deliver over the long distances from power stations to your home. AC voltage can be easily stepped up or down using transformers.

Best for Batteries: DC
Why: Batteries store and deliver energy in a constant, one-way flow. You cannot store AC power in a battery – it must be converted to DC first for charging.

Best for Solar Panels: DC
Why: Solar panels generate DC electricity naturally from photons hitting silicon cells. An “inverter” is required to convert this DC power to AC power for home use or feeding back to the grid.

Best for Electric Vehicles: DC (for the battery) and AC (for the motor)
Why: EVs store energy in DC batteries but often use AC motors for efficiency. The onboard inverter handles the conversion.

Always AC (Direct from Wall):

• Washing machines and dryers
• Conventional ovens and cooktops
• Air conditioners (central units)
• Most power tools with cords

Always DC (With Adaptor or Battery):

• Mobile phones and tablets
• Laptops and monitors
• LED light bulbs
• Gaming consoles
• Routers and modems
• Doorbell cameras
• Portable speakers

Can Be Either:

• Some desk fans (AC if plugged in, DC if USB-powered)
• Christmas lights (older ones are AC, newer LED strings are often DC)
• Electric motors (depends on application)

If you’re planning any electrical work or installations:

1. For Solar Installation: Understand inverter types and sizing – this is the critical component that converts your panels’ DC output to useable AC power
2. For International Travel: Check all your device labels now and make a list of what needs converters versus simple plug adaptors
3. For DIY Projects: Always use proper AC-to-DC converters rated for your project’s requirements – never attempt direct connections between AC and DC systems

Remember: When in doubt, consult the device manual or a qualified electrician. In Australia, any mains electrical work must be performed by a licensed electrician – it’s not just good practice, it’s the law.