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Lamps => Modern => Topic started by: Vince on January 31, 2010, 01:26:34 PM

Title: 3-way lamps question.
Post by: Vince on January 31, 2010, 01:26:34 PM: Most incandescent 3-way lamps says "Base-down only", but why exactly? Are they made differently than standard incandescent lamp? (Maybe something doesn't stand the heat in the base?)
Title: Re: 3-way lamps question.
Post by: Medved on January 31, 2010, 03:19:08 PM: I guess the insulation clearance might cause troubles, when at higher temperature: At BU the base take all the hot air from the bulb...
Title: Re: 3-way lamps question.
Post by: Lumalux on July 02, 2010, 12:02:41 PM: I always figured it had something to do with the filaments sagging and shorting out each other.

My mom has a bridge lamp with a 3-way socket and has never had any problems with that.
Title: Re: 3-way lamps question.
Post by: rjluna2 on July 02, 2010, 03:25:06 PM: The filament is close to lower part of the globe area and that is why they designed to burn the base down instead of the universal position. Not like the general bulb where the filament is usually centered at the globe area....
Title: Re: 3-way lamps question.
Post by: Jace the Gull on July 04, 2010, 02:01:00 PM: most of our today's 3 way lamps have vertical filaments. but I remember the old times, and some that I have in my collection that has horizontal filaments....but I got some EVEN older lamps that has filaments that forms in C shaped or a curved upward shapes with a lot of filament supports! I even have some Mazda lamps..that are 3 ways (most are dead actually)
Title: Re: 3-way lamps question.
Post by: Vince on July 04, 2010, 07:22:44 PM: I do have a 3-way lamp with CC-6 filaments. Some chinese 3-way lamps still have C-9 filaments! I discovered that when I blew up a burnt out 3-way lamp in a microwave LOL ;D (You should try, that's cool!)
Title: Re: 3-way lamps question.
Post by: Adderall on May 02, 2011, 09:33:05 PM: high-wattage incandescent lamps generally expected to be used base up, like reflector lamps and old school 150 and 300W lamps have a heat shield, usually a shiny thin metal disk near the base, inside the glass.

three way sockets are almost never used in any position but base down.
Title: Re: 3-way lamps question.
Post by: Silverliner14B on May 05, 2011, 03:27:08 PM: The reason for the burning position restriction on 3 way lamps is because they can get hot with two filaments in operation, and base up operation can dry out the basing cement and cause the bulb and base to seperate. Some low wattage 3 way bulbs (such as the 30-70-100w) can be burned in any position.
Title: Re: 3-way lamps question.
Post by: Jace the Gull on July 31, 2011, 02:31:12 PM: 95 to 99 percent of the 3 way fixtures are usually base down table lamps anyway! :D ;) ;D
Title: Re: 3-way lamps question.
Post by: Vince on July 31, 2011, 03:56:40 PM: Well I've been dumb enough to buy a base-up 3-way lamps several years ago XD
Title: Re: 3-way lamps question.
Post by: joe_347V on July 31, 2011, 09:11:07 PM: Quote from: Vince on July 31, 2011, 03:56:40 PM
Well I've been dumb enough to buy a base-up 3-way lamps several years ago XD

I never knew they sold base up three way lamps :o

All of mine say base down only.