Triumph TR7 Instrument Panel Bulb Size

Additional Notes

• The Triumph TR7 instrument panel specifications reference two ANSI standard miniature wedge bulb types across its production years: the 74 and the 194, both rated at 12 volts.
• The 74 is a T5 miniature wedge bulb operating at 1.4 watts, while the 194 is a T10 miniature wedge bulb operating at 3.78 watts, making the 194 a notably higher-wattage lamp despite sharing the same wedge base category.
• Both the 74 and 194 are classified under ANSI standards applicable to the US and Canadian markets.
• The T5 and T10 designations refer to the bulb's tubular envelope width, expressed in eighths of an inch, meaning a T5 measures 5/8 inch and a T10 measures 10/8 inch across the glass envelope.
• Although both bulbs use a wedge-style base, the physical size difference between the T5 (74) and T10 (194) envelopes means the two types are not interchangeable in instrument panel sockets.
• The Triumph TR7 used the 194 bulb for model years 1975, 1977, 1978, and 1980, while the 74 bulb was specified for 1976, 1979, and 1981, indicating the instrument panel socket specification changed multiple times across the production run.