# Mercury Vapor Lamp with Metal Halide ballast?

**URL:** <https://boards.straightdope.com/t/mercury-vapor-lamp-with-metal-halide-ballast/730241>\
**Category:** Factual Questions\
**Created:** [September 7, 2015, 2:39pm UTC](https://boards.straightdope.com/t/mercury-vapor-lamp-with-metal-halide-ballast/730241 "2015-09-07T14:39:08Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Mdcastle](https://avatars.discourse-cdn.com/v4/letter/m/958977/32.png) [@Mdcastle](https://boards.straightdope.com/u/Mdcastle)\
**Post date:** [September 7, 2015, 2:39pm UTC](https://boards.straightdope.com/t/mercury-vapor-lamp-with-metal-halide-ballast/730241/1 "2015-09-07T14:39:08Z")

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I’ve heard that Mercury Vapor and Metal Halide lamps are basically interchangeable as far as far as magnetic ballasts go, provided the correct wattage lamp is used. Does this also hold true for dimmable electronic ballasts as commonly used for grow lights. Will this

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>
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Drive a 400 watt Mercury Vapor lamp?

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**Author:** ![PoppaSan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/poppasan/32/189_2.png) [@PoppaSan](https://boards.straightdope.com/u/PoppaSan)\
**Post date:** [September 9, 2015, 1:05am UTC](https://boards.straightdope.com/t/mercury-vapor-lamp-with-metal-halide-ballast/730241/2 "2015-09-09T01:05:37Z")

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but they’re not interchangeable.