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GE CONSTANTCOLOR 70W Metal Halide Bulb CMH70TU/830/G12

A 70W CMH source delivering 6,200 initial lumens at a warm 3000K with CRI 83 — reliable color rendering for commercial and accent applications.

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Overview

The GE CONSTANTCOLOR CMH70TU/830/G12 is a 70-watt ceramic metal halide lamp producing 6,200 initial lumens at a 3000K color temperature with a CRI of 83. The ceramic arc tube construction — the defining characteristic of CMH over standard quartz metal halide — provides tighter color consistency from lamp to lamp and better color stability across the lamp's life. At 3000K, the output sits in warm white territory, making this a practical source for retail display, hospitality, and architectural accent lighting where a flattering, inviting tone is the design intent. For camera work, the 83 CRI is workable in controlled environments but will show limitations in side-by-side comparisons with CRI 90+ sources when rendering saturated colors or fine tonal gradations.

The T6 bulb shape measures 3.56 inches in length, fitting the enclosed optical systems typical of CMH downlights and track fixtures. The G12 bipin base is the industry standard for this wattage class. As with all ceramic metal halide sources, the lamp requires a ballast matched to ANSI code M139/E — the ballast drives the high-voltage ignition pulse and regulates current through the arc tube, and a mismatch will prevent ignition or shorten lamp life significantly. The 15,000-hour rated life is achievable under proper operating conditions: correct burning position, complete burn cycles, and avoidance of frequent cold re-strikes. Color temperature should be verified at initial installation, as it will stabilize after the first 100 hours of operation.

Specifications

Brand
GE
Model
CONSTANTCOLOR CMH70TU/830/G12
Wattage
70W
ANSI Code
M139/E
Bulb Shape
T6
Base Type
G12
Color Temperature
3000K
CRI
83
Initial Lumens
6,200
Rated Life
15,000 hours
Length
3.56 inches

Frequently Asked Questions

The CMH70TU/830/G12 outputs at 3000K with a CRI of 83. That warm white sits between tungsten and neutral white, making it suitable for retail and architectural applications, though for critical camera work CRI 83 falls short of the 90+ threshold most gaffers prefer for accurate skin tone reproduction.
The ANSI code is M139/E. This determines the ballast type required — this lamp must be paired with a compatible M139/E-rated ballast. Running it on a mismatched ballast will cause premature failure or prevent ignition.
GE rates this lamp at 15,000 hours. To reach that figure, the lamp should be operated in the burning position specified for the fixture and allowed to complete full burn cycles — frequent cold re-strikes significantly reduce rated life in metal halide sources.
Metal halide is substantially more efficacious than tungsten — at 6,200 initial lumens from 70W (roughly 88 lm/W), it runs far cooler per unit of light output than a comparable incandescent, which typically yields 15–20 lm/W. That said, the arc tube and outer envelope still reach high temperatures; maintain minimum clearances specified in the fixture manual.
Standard CMH/metal halide lamps are not dimmable with conventional phase-cut dimmers. Dimming requires a purpose-built electronic dimmable ballast rated for this ANSI code. Attempting to dim on an incompatible ballast risks color shift, arc instability, and premature lamp failure.

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