Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « on: March 06, 2026, 04:01:14 PM » Author: Waxsoda61774308
I recently purchased some 400watt MH gear and would like to know if it’s safe to run the lamp out of an enclosure. I do know that MH lamps have the tendency to sometimes explode apon EOL.
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #1 on: March 06, 2026, 04:28:53 PM » Author: BT25
Running them vertically reduces the likelihood.
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #2 on: March 06, 2026, 04:29:57 PM » Author: Multisubject
If it is an exposed rated lamp, then I would say yes this is probably safe. But assuming it is an enclosed rated lamp (as most are), then I would say maybe. If the lamp is used (or you don't know it's history), I would not at all run it in the open. Technically even a brand new lamp can explode with a severe enough manufacturing defect, but I haven't seen that. Explosion is always a risk, but if you shield the lamp or shield yourself you should be relatively safe even with an old lamp.
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #4 on: March 08, 2026, 10:33:52 AM » Author: dor123
There was a generic 6500K 400W elliptical clear MH lamp at Peamit Store, that exploded despite burned base-up in a highbay fixture: https://www.lighting-gallery.net/gallery/displayimage.php?pos=-251405
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #5 on: March 08, 2026, 08:20:41 PM » Author: Waxsoda61774308
This is the lamp, it’s definitely not a shielded arc tube. It’s also new-old stock found in my churches basement after they got rid of their high-bays in favor of LED’s.
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #6 on: March 08, 2026, 11:04:49 PM » Author: WorldwideHIDCollectorUSA
If your lamp has operating position restrictions, it is especially paramount to run it in its designated operating position such as VBU for base up or HOR for horizontal. If it is  rated for universal burning, it should safely operate in any position, but I recommend even operating universal burn lamps base up for maximum longevity.
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	Re: Is it safe to run a 400watt GE multi vapor lamp without an enclosure? « Reply #7 on: Today at 08:10:23 PM » Author: wide-lite 1000
https://www.scribd.com/document/132183345/GE-1984-Lamp-Catalog  Page 45 + 46 only say "ENCLOSED FIXTURE ONLY" if the 400w lamp is burned other than VBU or VBD +-15°.  Since your lamp is new , I see no problem ! The assembly plant I work in was lit by unprotected 400w M-59 lamps for 20 years. The maintenence morons NEVER replaced a lamp until it went out ! In that time I only saw ONE non-passive EOL in over 100+ lamps !  Unprotected MH lamps were used for years . Yes , it's possible but unlikely for a MH to go BOOM ! Of all of the non-passive EOL lamps I've seen in the wild , a vast majority of them never penetrated the outer bulb .  The likelyhood of non-passive EOL increases dramatically as EOL approaches .
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