Fluorescent lamp ballast question - Page 1
Forum section: electronics / projects

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 05:05:46 am
content: This 120V, 60Hz lamp uses three F20T12-KB 20W 24-inch tubes (2 straight pins at each end) and a starter and a 2-wire ballast (non-electronic) for each lamp. Wired like this:I can't find any 2-wire ballasts to replace these. I find several 6-wire. These have 2 primary and 4 secondary wires. The secondaries connect one wire to each of the 4 pins.Can I upgrade these lamps to use these ballasts by eliminating the starter? Or just use them as indicated in the second diagram?The ballast I'm looking at:https://www.amazon.com/Keystone-Electronic-KTEB-120-1-TP-Fluorescent-Ballast/dp/B00C9GVRQ4/ref=sr_1_1?keywords=B00C9GVRQ4&qid=1565498937&s=gateway&sr=8-1Thanks.

author: trevatxtal
author_rank: Contributor
timestamp: August 11, 2019, 05:33:28 am
content: on the same page you refer to is a two wire ballast.https://www.amazon.com/Keystone-KTEB-120-1-TP-EMI-Fluorescent-Ballast-1-Lamp/dp/B075V3V47K/ref=pd_sbs_328_2/132-0694794-5487633?_encoding=UTF8&pd_rd_i=B075V3V47K&pd_rd_r=7564f7c7-058d-4353-9f4b-e0cfea937be3&pd_rd_w=4xUuO&pd_rd_wg=ZpewI&pf_rd_p=1c11b7ff-9ffb-4ba6-8036-be1b0afa79bb&pf_rd_r=1AZXZCJ1229FFZH9TTF8&psc=1&refRID=1AZXZCJ1229FFZH9TTF8.

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 05:49:21 am
content: I see 4 wires coming out of the left end of that one.I need 2 wires. Not 2 secondary wires, 2 wires total. It’s basically an inductor.

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 05:53:40 am
content: That's not the same. The ballasts he's referring to as "2 wire" are simple choke ballasts, they are nothing more than a coil of wire on an iron core. I think they banned conventional magnetic ballasts at some point so it may be hard to find an exact replacement however it's not difficult to rewire the fixture to use a modern electronic ballast like that one linked.Personally I like the old preheat choke ballasts with a separate starter, they have a certain charm and they tend to be very reliable. Not quite as efficient as most of the electronic ones though.

author: Zero999
author_rank: Super Contributor
timestamp: August 11, 2019, 08:31:00 am
content: I thought 120V was too lower voltage for three fluorescent tubes in series? Hence the need for a transformer.Inductive ballasts needn't be inefficient. It's just they were built to a price, using minimal copper and iron.Rewiring the fixture to use a modern electronic ballast is a sensible option, or replace the tubes with LEDs.

author: themadhippy
author_rank: Super Contributor
timestamp: August 11, 2019, 11:33:04 am
content: Quotenot in the uk,how many do you want?https://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Lighting_Fluorescent_Index/Flo_Control_1/index.html#Control_Gear

author: David Hess
author_rank: Super Contributor
timestamp: August 11, 2019, 06:34:03 pm
content: Quote from: iXod on August 11, 2019, 05:05:46 amYes.QuoteYes. The electronic ballast does not require an external starter. That function is built in.Quote from: james_s on August 11, 2019, 05:53:40 amPreheating also results in much longer lamp life. The instant start ballast blow the emissive coating off of the filaments.

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 07:01:42 pm
content: Quote from: Zero999 on August 11, 2019, 08:31:00 amYou'll never find fluorescent tubes in series from choke ballasts on 120V, three tubes means three ballast chokes. 3-lamp fixtures are rare though, most use multiples of 2 lamps which for 30W and larger will most commonly be two lamps in series on an autotransformer ballast, 4-lamp fixtures will have two ballasts.Now that everything is electronic you'll typically find anything up to 4 lamps will be on a single electronic ballast with 4 outputs.

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 07:21:41 pm
content: OP here. Thanks for the replies.3 lamps in *parallel* (each with 1 dedicated ballast/choke and starter—see original post with wiring diagram) .I’ll probably use these electronic ballasts.Thanks.

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 07:33:53 pm
content: Quote from: themadhippy on August 11, 2019, 11:33:04 amThey probably don't have any 120v 30W chokes (using a separate starter, not switch-start) do they? In the land of 240v and household 3-phase...

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 07:36:54 pm
content: This is actually in a small photographer’s light table, used to view transparency film.

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 07:39:36 pm
content: Quote from: iXod on August 11, 2019, 07:33:53 pmI think 22W is as high as it ever got for choke ballasts on 120V, lamps up to about 24" in length.For HID lamps you could get HPS (SON) chokes up to 100W, there are two types of 100W HPS lamp, one that operates at around 50V for 120V choke ballast applications and one that operates around 100V. Larger lamps were occasionally used on choke ballasts where 240, 277 or 480V was available in commercial/industrial settings but 120V mandates the use of autotransformer ballasts.

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 07:55:19 pm
content: Quote from: james_s on August 11, 2019, 07:39:36 pmCrikey. I can’t even remember my lamp size.They are 20W lamps of course.But UK won’t have any 120V product.Not interested in HIDs.

author: themadhippy
author_rank: Super Contributor
timestamp: August 11, 2019, 09:28:27 pm
content: Quoteswitch start means it uses a starter,the type without starters are commonly known as quick start.QuoteBut we've got plenty of 110v stuff,normally found on building sites.

author: james_s
author_rank: Super Contributor
timestamp: August 11, 2019, 09:40:05 pm
content: That depends on where you are. When I hear "switch start" I think of the inexpensive fluorescent desk lamps that were once common, where instead of a starter the power switch is a momentary contact wired as a starter would be. To turn on the lamp you hold down the power button until the ends glow and then release it and the tube starts. To turn it off the switch interrupts the power.The most common magnetic ballasts for larger lamps in the US are "rapid start" which are autotransformers with separate windings to heat the cathodes. There are also "instant start" types that use a high enough voltage to strike the lamps without heating the cathodes, although this generally leads to shorter lamp life.

author: iXod
author_rank: Frequent Contributor
timestamp: August 11, 2019, 10:11:51 pm
content: Quote from: james_s on August 11, 2019, 09:40:05 pmThat's correct.themadhippy, see #1 under this topic:http://www.repairfaq.org/sam/flamp.htm#fb2Fluorescent lamp circuits are of 3 types:- "starter" start (uses a separate starter component) automatically starts- switch start (no separate starter) - must hold switch in a temporary "start" position- autostart (electronic ballasts are of this type) "quick start"

author: themadhippy
author_rank: Super Contributor
timestamp: August 12, 2019, 01:32:49 am
content: As mentioned aboveQuoteIn the land of 240v and 50Hz, florry tubes were you need toQuoteare about as common as rocking horse shit. However whether they use a manual switch,or starter the ballast is the same.

author: iXod
author_rank: Frequent Contributor
timestamp: August 12, 2019, 02:28:01 am
content: Haven’t you seen those old large workbench magnifiers on an articulated arm with a round fluorescent tube in it? Those typically have a switch-start circuit.

author: james_s
author_rank: Super Contributor
timestamp: August 12, 2019, 03:24:31 am
content: Quote from: themadhippy link=topic=203694.msg2609667#msg2609667Like I said, it depends on where you are. The old manual switch start configuration was *very* common in the USA, I still have at least 3 lights of that type, one desk lamp and two handheld UV lamps, all from the 1970s. The stove in the kitchen at our cabin (also 1970s) has the same arrangement on the fluorescent light over the control panel.For portable fluorescent lamps it was almost ubiquitous, they made many millions and millions of them, they used to be common as muck.

author: james_s
author_rank: Super Contributor
timestamp: August 12, 2019, 03:34:00 am
content: Quote from: iXod on August 11, 2019, 07:36:54 pmMost of this discussion is academic at this point. Unless you want to retain the old style preheat start magnetic ballast arrangement to keep a vintage item original, just replace the ballasts with a modern multi-lamp electronic ballast. The type is not even all that critical, T12 tubes all run at about the same current (ignoring HO and VHO types which you'll rarely run into at home) and most electronic ballasts will work with a fairly wide range of lamp types. All you need is a ballast that lists F20T12 as a supported lamp type and you are good to go.For reference, F20T12-KB decodes to Fluorescent, 20 Watts, Tubular, 12/8" (1.5") diameter, "Kitchen & Bath" which is one of the old halophosphate phosphor blends, IIRC it was a bit warmer than "Cool White", but not as warm as "Warm White". Electrically speaking, all F20T12 lamps are identical.

author: iXod
author_rank: Frequent Contributor
timestamp: August 13, 2019, 04:23:00 pm
content: Quote from: themadhippy on August 11, 2019, 09:28:27 pmCan you point me to some 110v 20W 2-wire chokes for F20T12 lamp circuits? I've looked and don't see anything.

author: james_s
author_rank: Super Contributor
timestamp: August 13, 2019, 06:02:26 pm
content: I don't think they exist, and if they did, shipping iron chokes from the UK would be quite expensive. The UK building site stuff I've seen is mostly power tools and incandescent lamps. The single lamp 120V choke ballast arrangement was a North American thing.Is there a reason you don't want to just use a modern electronic ballast? It's trivial to install one.FWIW these little choke ballasts are used in the marquee lights of most vintage arcade games so there are still some NOS ones out there.https://www.ebay.com/itm/New-Video-Arcade-Game-Fluorescent-Light-Ballast-For-Header-Marquee-Light/333028048556?Here's another, 6 available as I write this:https://www.ebay.com/itm/Advance-LC1420CTP-PRE-HEAT-BALLAST-POWERS-1-F20T12-120V/183766641654?

author: iXod
author_rank: Frequent Contributor
timestamp: August 13, 2019, 10:51:29 pm
content: Quote from: james_s on August 13, 2019, 06:02:26 pmThose ballasts are hard on bulbs and EMI-noisy. But it looks like i'll be doing that anyway.

author: james_s
author_rank: Super Contributor
timestamp: August 13, 2019, 11:14:43 pm
content: That depends on the ballast. There are lots of good quality electronic ballasts that are gentle on the lamps, much more so than the old choke ballast preheat start. The good ones typically called it "programmed start", they apply power to the cathodes for a determined period of time and then strike the arc.