Author Topic: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat?  (Read 2665 times)
ace100w120v
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F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « on: March 14, 2019, 12:02:58 AM » Author: ace100w120v
Had this come to me in a dream the other night of all things but then realized it is plausible, or is it?

We all know that in many cases F15T8 lamps work just fine on preheat or manual preheat setups, and are often in fact brighter and in practice pull fewer line-amps.

Given this: With no real "F20T8" to speak of (I have one that is a BLB but it is a Chinese lamp so who knows) would F17T8 lamps be brighter and draw less on 14/15/20 watt NPF preheat ballasts?  Would the 24" 18w krypton filled "Appliance" T8 lamps work? Would they be brighter? Save energy? I ask since apparently in 230v regions where preheat (regionally known as "switchstart") fittings are still more of a thing, F36T8s are a drop-in retrofit as I understand, much as our 34w F40T12 lamps are an energy saving replacement for F40T12 lamps on our rapid-start ballasts. 

Any idea which of the two might be brighter and draw less and possibly be easier on a ballast? I realize that a ballast is a current limiter, but I know lamps influence ballasts too with their arc voltage and other electrical characteristics. 

Similarly:  Would an F32T8 work, and/or save energy/and/or be brighter, on a 30/40w NPF preheat ballast?

Reason I ask is that these ballasts are usually notorious for under powering their respective 20 or 40 watt lamps.  On the similarly dim and under powering F40T12 low power factor residential-grade rapid start ballasts, 34 watt "Energy saver" lamps are usually brighter yet pull MORE line-amps, and are a better fit provided they don't cook said ballast.  Might F18s be brighter but draw more? What about F17s?

Now...what about the "energy saver" 25w or 28w F32T8s on NPF 30/40 watt preheat?
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dor123
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Re: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « Reply #1 on: March 14, 2019, 05:53:02 AM » Author: dor123
You can operate F18T8 on preheat F20T12. Outside the US, 18W T8 designed as retrofit for 20W T12 on their series chokes.
In fact: Not so long ago, 4x18W preheat troffers were common here in Israel, which were operated with two 36/40W T8/T12 ballasts, two tubes for each choke 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.

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Re: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « Reply #2 on: March 14, 2019, 06:21:49 AM » Author: funkybulb
here interesting part The 18 watt 2 footer appliance lamp is actually one of oldest lamp before EU thought
of being a use retrofit lamp.  and it will work fine on choke ballast.  and same for 36 watt tubes on preheat
ballast.  now I have ran 17 watt on a 20 watt choke
that not full power.  it one of lamp that have higher
arc voltage that is very close for starter trigger voltage
a weak lower trigger voltage starters should
not be use as the starter would glow and blink
the lamp now and then. but the F17 watt lamp
is only 260 mA with higher arc voltage.  so lamp becomes over driven but higher arc voltage on the
choke runs cooler.  but you have more color choices
on lamps than your standard CW, WW and Daylight
F18s and 20 watt lamp with bit better choices.  I have ran F40T8 on European 5 foot fixture that can take 65 watt tubes. I got same results overdriven tube but cooler
ballast. but I not sure about running F32 on Our American Preheat ballast as those tend have auto transformer-choke ballast.  i worried it might stress out
the leading capacitor on lead lag type of ballast.

now you want a brightest lamp on a 20 watt preheat ballast?  I have lit F40 tube on F20 watt choke. it normally dont work it cause it lacked OCV
with a help of a capacitor and manual preheating
it lit at full power also the lowest ballast lost.  i manage
to run the the whole set up at 52 watts total
with power factor of .7   for a leading choke type setup
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dor123
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Re: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « Reply #3 on: March 14, 2019, 08:47:11 AM » Author: dor123
I think that the Americans began to use the F18T8 as an appliance lamp, after the European used it as a retrofit for F20T12.
I think that the Krypton T8 lamps (F18T8, F36T8, F58T8 and F70T8), were invented by Thorn lighting as a retrofit for T12 lamps. and the American later adopted the smallest F18T8 as an appliance lamp.
The light output of a fluorescent lamp, have nothing to do with the ballast power factor.
« Last Edit: March 14, 2019, 02:49:54 PM by dor123 » Logged

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.

ace100w120v
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Re: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « Reply #4 on: March 15, 2019, 02:58:18 PM » Author: ace100w120v
Interesting, I guess in theory my intuitions were correct?
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xmaslightguy
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Re: F17T8 or F18T8/K24" lamps on F20T12 preheat chokes? F32T8 on NPF preheat? « Reply #5 on: April 03, 2019, 10:49:36 PM » Author: xmaslightguy
I've come across plenty of F18T8's that aren't appliance lamps. They work fine on preheat, but not very well on RS. F17T8's work fine on preheat.
Oh and F20T8's do exist, I had a couple grow/aquarium type of them at one point.

You can get F32T8's to fire up on LPF preheat, but they're a bit finicky starting, and a UK S-10 starter works better than a FS-4

Both F36T8 & F18T8 were sold here in the US as T12 retrofit lamps, but I think it was only in the aquarium-lighting hobby.
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