AC and DC symbols: how to read electrical labels
AC means alternating current; DC means direct current. On equipment labels, AC is shown by a wave, approximately ~, and DC by a solid line above a broken line, approximately ⎓. These marks identify the current type for the labelled input, output or connection. [1]
KEY TAKEAWAYS
Recognise the shape and IEC number
IEC 60417-5032 is the alternating-current wave; IEC 60417-5031 is the direct-current solid line over a broken line. The characters ~ and ⎓ here are readable text approximations, not artwork for manufacturing a label. The IEC/ISO preview also lists 5034 for input and 5035 for output. [1]
Read input and output separately
IEC explains that equipment symbols identify parts, functional states and connections. Keep each mark attached to its location: an adapter’s input and output can describe different current types. Record the adjacent voltage, current and frequency text exactly instead of combining every number into one device rating. [2]
Interpreting a label without extrapolating its scope
Our reading: keep a current-type symbol attached to the labelled connection and its own voltage and current figures. Recognising AC or DC does not identify polarity, connector dimensions or the full specification of a replacement supply. Keep the component’s documentation with the record instead of copying electrical data from another model.
Article Sources
- IEC / ISO — IEC/ISO Graphical Symbols for Use on Equipment: preview
Primary source
Preview page 4: scope; page 6 visually checked on 4 October 2026: 5031 is a solid line over a broken line (DC), 5032 a wave (AC), with 5034 Input and 5035 Output. Text characters are approximations. Preview only; its 2 March 2026 snapshot date is not a standard-release date.
- IEC TC 3 — Graphical symbols for use on equipment
Primary source
IEC TR 62964 list: equipment identification, functional state and connections. Explains what symbols communicate, rather than certifying equipment.
Written and reviewed with AI assistance using the linked sources. No hands-on product testing or independent specialist review was performed.
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