Lamp symbol

A circle with a cross inside it, marking a lamp or indicator.

Also known as: Bulb symbol, Indicator lamp symbol, Circle with an X, Light symbol

Engineering & technicalScientificQuiet profile

Meanings

A circle crossed by two diagonal lines marks a lamp. The cross has no physical counterpart in the component — unlike most schematic symbols it depicts nothing, and is simply a mark chosen to be unmistakable at small size.

Common modern usageVerified fact
Marks a lamp or indicator light in a circuit: a component that produces light when current passes through it.
Contexts: Electrical equipment
Common modern usageVerified fact
Does not depict the component. Unlike the capacitor's plates or the inductor's coil, the cross inside the circle stands for nothing physical and was chosen for legibility at small size.
Contexts: Electrical equipment
Common modern usageCommon usage
Appears in several forms across conventions — a circle with a diagonal cross, a circle with an upright cross, or a circle with a wavy line for a signal lamp — which are not fully interchangeable between standards.
No single canonical drawing is asserted here.
Contexts: Electrical equipment

Visual description

A plain circle with two straight lines crossing at its centre, drawn corner to corner so the cross touches the circle at four points.

A fuller structured visual breakdown is not yet documented for this symbol.

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.

Sources

Incandescent light bulb
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Electronic symbol
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Circuit diagram
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.

Last reviewed 2026-07-31

Part of

Circuit and schematic symbols

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Meanings

Common modern usageVerified fact

Marks a lamp or indicator light in a circuit: a component that produces light when current passes through it.

Contexts: Electrical equipment

Common modern usageVerified fact

Does not depict the component. Unlike the capacitor's plates or the inductor's coil, the cross inside the circle stands for nothing physical and was chosen for legibility at small size.

Contexts: Electrical equipment

Common modern usageCommon usage

Appears in several forms across conventions — a circle with a diagonal cross, a circle with an upright cross, or a circle with a wavy line for a signal lamp — which are not fully interchangeable between standards.

No single canonical drawing is asserted here.

Contexts: Electrical equipment

Confidence

IdentityHigh confidence: High confidence because the identity is documented in encyclopedic references, but multiple independent sources agree.
Historical originLow confidence: Low confidence because the historical origin is documented in encyclopedic references, but only a single source has been found so far, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.
Current useHigh confidence: High confidence because the current use is documented in encyclopedic references, but multiple independent sources agree.
Visual matchModerate confidence: Moderate confidence because the visual match is documented in encyclopedic references, but early or supporting evidence is limited, but the regional or cultural match to this specific claim is not precise.

Sources

Incandescent light bulb
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Electronic symbol
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.
Circuit diagram
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the component is, how its symbol is conventionally drawn, and where the ANSI and IEC conventions differ. Not used for any claim about the text of IEC 60617, which is paywalled and was not consulted.

Last reviewed 2026-07-31