dor123
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| I've noticed that the Americans have a special type of fluorescent fixture that isn't exists in 220-240V territories, which called tandem fixture, in which two or more fluorescent fixtures, are chained together into a single, very long fixture, and probably all operating from a single shared ballast.
Why tandem fixtures aren't common outside the US?
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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HomeBrewLamps
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| They don't operate from single ballast, each fixture has it's own ballast..
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~Owen
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dor123
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| So why they called tandem fixture, if each fixture operating from its own ballast?
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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sol
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| Some have one ballast for the whole tandem strip. Just look at a ballast failure in Walmart...
Otherwise, it makes less fixtures to install and we all know time is money in our world.
It also makes it easier to use 2xF40 ballasts in a row of single lamps.
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sol
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| Just to be clear, I'm refering to the ubiquitous 8-foot tandem that uses 4-foot lamps end to end.
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HomeBrewLamps
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 Are something like these what you speak of? |
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« Last Edit: May 30, 2018, 04:44:02 PM by HomeBrewLamps »
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~Owen
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RyanF40T12
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| I run a few 2 lamp fixtures in tandem using a 4 bulb ballast. But only do it on T8.
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The more you hate the LED movement, the stronger it becomes.
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sol
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Are something like these what you speak of?
Not necessarily. Those are just one of the many styles available. There are many variants on this theme. Back in the T12 days, there was the abundance of louvres, most of which were available in tandem as well as single. Those originally had two ballasts although the newer T8 could have only one. There was also some 2-lamp tandem strips, they looked like two single lamp strips end-to-end. Those typically had only one RS ballast. Then came the newer ones that take T8 lamps and have one 4-lamp ballast. |
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RyanF40T12
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| I LOVE those type of fixtures, SOL.
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The more you hate the LED movement, the stronger it becomes.
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HomeBrewLamps
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I LOVE those type of fixtures, SOL.
Louvres? |
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~Owen
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dor123
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Some have one ballast for the whole tandem strip. Just look at a ballast failure in Walmart...
Otherwise, it makes less fixtures to install and we all know time is money in our world.
It also makes it easier to use 2xF40 ballasts in a row of single lamps.
I don't live in the US, so I can't see what happens there, but only in LG. Its looks like that the reason why tandem fixtures are non-exists outside the US, is the same reasons why multi-lamp ballasts are non-exists outside North America: We uses series chokes that can only operates one lamp (Or using one 36W T8 choke to run two 18W T8 lamps in series) at a time, and series chokes have the 230-240V mains as their OCV, so it is impossible to make a tandem fixture using series choke (It would require 4 separate chokes for each lamp). And as electronic ballasts that can operates 3-4 lamps being developed in Europe, tandem fixture won't became popular there. |
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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joseph_125
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| There is also a similar concept occasionally used called Tandem Wiring usually used with recessed troffers. In tandem wiring two separate fixtures would share ballasts.
For example two 2x4 2 lamp troffers would share a 4 lamp ballast, the master fixture has a ballast and two lamps, the slave is wired off the ballast in the master.
Another example using 2x4 3 lamp troffers would be to have a 4 lamp and 2 lamp ballast in the master on separate switches. The 4 lamp ballast powers the outer lamps in both units and the 2 lamp ballast powers the centre lamp in both units. This arrangement has the advantage of having trilevel switching (centre, outers, all)
Tandem wiring is usually done to use fewer ballasts per install. The main disadvantages is the installation cost and the annoyance troubleshooting them.
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Lightingguy1994
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| Tandem fixtures are popular here because it makes installing them faster and more practical in larger applications where most of the lights have to be continuous row mounted but they still needed to utilize the popular 4 foot lamps. So the 8 foot tandem was born. These are designed to look exactly like 2 separate 4 foot lights put in a row.
My old classroom in elementary school, it had 6 rows of 4 lamp louvered fixtures. Having most of them 8 feet long allowed for easier installation. (see attached photo)
The first row only needed 8 feet of lighting so one 8ft fixture went up. The middle row needed 12 feet, so 8ft fixture + 4ft fixture. Last row needed 16 feet of lighting, so 8ft +8ft.
Normally 8 foot fixtures require only 2 stem mount poles to mount to the ceiling, but because these ones were 8 lamp tandem, they have 4 ballasts so a middle stem was required for support, so 8 foot fixtures had to have 3 stems, where as the 4 foot ones only had 2. In the case of the 12 foot rows, the 4 foot fixture shared a stem with the 8 foot one.
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« Last Edit: July 20, 2018, 12:32:46 AM by Lightingguy1994 »
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joseph_125
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| Interesting that your school used three stem hangers for the 8' tandem louvers. My school originally had 8 foot tandem louvers too and they only used two per 8 foot section of fixtures.
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Lightingguy1994
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| How many lamps did the 8 foot tandems use at your school ?
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