What Is The Sign For AC Voltage? | Quick Visual Guide

Sign For AC Voltage On Power Supplies

On wall adapters and chargers, the AC side is shown with a tilde or with a sine wave icon. A typical line on a rating plate reads “Input: 100–240 V~ 50/60 Hz.” The tilde after V tells you the mains input expects alternating voltage. The same unit may print “Output: 12 V⎓ 2 A” for the direct-current side that feeds your device.

The graphical mark for alternating current used on equipment labels is defined in the international symbol set for electronics. You will see it referenced as the “alternating current” symbol in the IEC 60417 collection, which is the common source used by manufacturers. The DC counterpart appears in the same catalog. These two marks keep mains and low-voltage circuits unambiguous across models and regions.

Where You’ll See It On Adapters

Most bricks list line ratings near the plug icon. Look for “V~” next to a voltage range and a frequency in hertz. A current value marked with “A~” describes alternating current on the input side of test gear or distribution gear. Consumer adapters usually print current only on the DC output side, so you’ll read amps without a tilde there.

AC Voltage Symbol On Schematics And Meters

In circuit diagrams, an AC source often appears as a circle with a wavy trace inside. Some drawings drop the circle and show a stand-alone sine wave near the node. On instruments, the same idea shows up as “V~” for voltage, “mV~” for millivolts, or just a tilde over the V. When you select that position on a handheld meter, you are telling it to measure alternating voltage.

The sine-wave glyph itself exists as a standard character in Unicode, named “SINE WAVE” and documented as the symbol used for alternating current. You’ll see it in datasheets, manuals, and UI text when designers want a compact sign that reads well at small sizes.

AC Vs DC: Telling The Signs Apart

AC marks use a wave. DC marks use straight lines. On many labels the DC sign is a solid line above a dashed line; on some texts it appears as the dedicated character ⎓. If a label prints “V⎓” or shows those lines, the port expects steady direct voltage. If you see “V~”, the port is for alternating mains.

This difference prevents accidents. Feeding DC into an AC-only port can trip protection or damage hardware. Feeding AC into a DC-only jack can destroy regulators or cause shock risk. The small glyphs exist so that anyone can read a plate at a glance and pick the correct plug or meter mode.

Look-alikes To Avoid

Do not confuse the tilde with the “almost equal” sign (≈). The double-wiggle mark does not mean AC in power labeling. Also avoid mixing the hyphen with a true tilde when you type specs into documentation; “V-” means negative voltage, not alternating voltage.

Single-Phase And Three-Phase Variants

Equipment that runs on single-phase line power may carry a dedicated single-phase mark alongside the basic AC symbol. Industrial gear that needs three-phase power uses a symbol with three waves. Sometimes a small “N” is drawn to show a neutral conductor when one is required. These additions sit near the main AC mark so installers can match the correct supply.

Distribution boards and heavy tools often print the phase arrangement on a diagram sticker. Colors and letters vary by region, yet the wave shapes remain consistent, which keeps the reading of the panel clear across languages.

Typing The AC Sign In Text

If you need a text character, the simple tilde “~” works in plain notes and labels. For typeset manuals, the sine-wave character “∿” looks cleaner at small sizes and carries the intended meaning in standards texts. When you write specs, “V~” reads as volts AC, “A~” reads as amps AC, and “VAC” is a common shorthand in purchasing lists and UI strings.

In HTML you can paste the sine wave directly or use its code point. Many teams still prefer the basic tilde because it is easy to enter on any keyboard and survives font changes without surprises.

Reading Real-World Labels

Here are common lines you’ll meet on plates and in datasheets, with a quick read of each line so you can verify the port or range before you connect.

Examples

INPUT: 200–240 V~ 50/60 Hz 0.5 A — Line input accepts AC at European mains levels; the adapter draws up to half an amp from the wall.

OUTPUT: 19 V⎓ 3.42 A — DC barrel jack or cord delivers regulated direct voltage to the load.

RANGE: 600 V~ — Meter range switch or display shows the maximum alternating voltage you can measure on that setting.

RANGE: 600 V⎓ — Meter limit for direct-voltage measurement on that jack.

How Meters Treat AC Voltage

Handheld meters sense AC differently from DC. They look at a changing waveform and report an RMS value so that the number matches the heating effect of a steady source. Cheap models assume a sine wave and read accurately on mains. True RMS models read many shapes correctly. The symbol “V~” tells you the meter is in the right mode for a time-varying signal.

Some meters add a small wave over the letter V, rather than printing “V~.” Others show a small sine wave next to the autorange icon. Brands differ here, yet the wave theme stays the same, which keeps the dial easy to parse in low light.

AC Labels Across Regions

Consumer gear tends to use “V~” and a frequency pair, which travels well across markets. North America, the EU, and many parts of Asia ship adapters with the same dual-frequency line because switching supplies handle both. Meters sold worldwide keep the same wave marks on the dial, so once you learn them, you can read any brand with ease.

Legacy drawings may include older wave art or brand-specific icons. The text near the symbol remains a good guide: if you see a hertz value with a tilde, that spec refers to alternating voltage or current on the mains side.

Troubleshooting Misreads

If a plug runs hot or a device resets when you power it, recheck the marks. A plug pack rated for 120 V~ may buzz or fail at 230 V~. A meter in DC mode will under-read an AC outlet and can mislead you during fault finding. Swap to “V~” and retest. If a diagram shows the sine wave inside a circle, that node is an AC source, not a DC rail.

Keep an eye on adapter outputs. Laptop bricks list a DC output with the line-and-dash mark; the AC sign appears only on the input line. Universal travel adapters pass through the wall AC; they do not convert mains to DC without a separate supply.

Takeaways For Fast Recognition

• Wave means alternating. Tilde or sine wave both point to AC.
• “V~” and “A~” label AC voltage and current. “V⎓” marks DC.
• On drawings, a sine wave near a node signals an AC source.
• Single-phase and three-phase variants add context but keep the wave theme.
• Match the mark on the plate to your source, plug, or meter mode before you connect.

Markings are tiny, so slow down and double-check at each point before you connect a plug, a cord set, or a probe for safety.

Why Two Notations Exist: ~ And ∿

Engineers needed a mark that reads instantly at tiny sizes, on etched plates, and in line art. The tilde meets that need on low-cost plastics and embossed metal. It prints cleanly on nearly any printer and still looks like a wave when space is tight. Manuals and UI text often keep the plain tilde for the same reason.

When designers have room, the sine wave glyph ∿ gives a crisp wave shape that stands apart from letters and numbers. It also lines up with the icon used in diagrams. Both marks convey the same idea. If a label lists “230 V~” and a diagram nearby shows a sine wave, they both point to alternating voltage at that point in the system.

RMS, Frequency, And What “V~” Implies

AC voltage swings above and below zero. To put a single number on that swing, line power is given as an RMS value. A meter in AC mode displays an RMS reading, which matches the heat you would get from a DC source of the same value. That is why a 230 V~ line compares with a 230 V⎓ heater for power delivery, which itself describes a moving waveform over time.

Next to the voltage you often see a frequency in hertz. Common mains lines list 50 Hz or 60 Hz, and many adapters accept both. Some supplies also print a current draw at a given line voltage so you can size fuses and cords. If you see “0.7 A~” near the input rating, that value describes the alternating current pulled from the wall under load.

When Marks Share Space With Safety Icons

Plates often group the AC sign with other power symbols. The protective-earth sign looks like three stacked lines forming a fork into a bar; the double-square mark indicates Class II insulation; the line and neutral letters show terminations. These sit near “V~” on inlets, which helps a tech wire the panel and pick the right cord cap in the shop.

Some gear ships with a range select switch. If the plate lists “115/230 V~,” set the switch for your region before connecting the inlet. Modern switch-mode supplies rarely need this switch, yet many amplifiers and older tools still use it. The presence of the tilde does not tell you about that switch position, so read the full plate before energizing.

When You Might Not See A Mark

Wall sockets usually have no text. The outlet type implies AC by design, and national standards prescribe the shape and rating. Power strips follow the same pattern. Inside products, board silk often abbreviates AC points as “AC IN,” “HOT,” or “L.” In those cases the wave symbol is redundant, so the tilde may be omitted to save space.

Publishing And Accessibility Notes

When you compile a manual, use text and symbols together so screen readers can announce both. A plain “AC” string beside the wave helps assistive tools and preserves meaning in fonts that lack the glyph. In HTML you can include the sine wave in a code block or alt text for icons so the meaning survives style changes and theme tweaks on the site.

Here are two helpful reference pages that show these marks in formal sources. The IEC database lists the equipment symbol for alternating current and its DC counterpart. The Unicode code chart labels the “SINE WAVE” character as “alternating current,” which explains why many manuals use it as a compact sign.

Standards resources: IEC 60417 symbols online • Unicode names list for U+223F • IEC 60417 DC symbol entry