Introduction: Mod Light Fixture to Low Watt PL

In this instructable (my first one yay) we will mod a 2x36 w fluorescent light to 9 w

The lamp we will use is 9 w PL. It is incomplete CFL and it is smaller in size and better in reliability and lifetime than normal CFL

Almost any light can be converted to PL lamps. All we need is to accept low levels of lighting

Step 1: 36 Watt

The story takes place in a dorm room. My room (3 x 3 meter) was lit with 72 watts fluorescent

Its not only my room - lighting all over the building is HUGE overkill. So before we start lets get out and remove some starters in the common area between the rooms too. After we mod our light lets call in some mates from the dorm and help them change lights too

Now Im leaving the room and am required by the admins to leave full 72 watts fluorescent after me. The instructable was actually made when converting the thing back to 72 watt

Step 2: 9 Watt

Lets choose the lamp size we need

The PL lamps have efficiency (light output / watt) same as fluorescents and CFLs

PLs come in flat (5 - 11 w) and square (10 - 26 w) shapes. Efficiency rises with the length of the lamp and is better in the flat lamps. The 11 w PL (the longest flat lamp) is about 1.2 - 1.5x the efficiency of others and equals to more than 60 w incandescent

Some manufacturers call PLs with the names DULUX S (flat) and DULUX D (square)

Now we choose the ballast - an extra device that is explained in the end of the instructable and is required to run fluorescents

There are ballasts of 2 types (electronic and magetic) and various sizes to match the watts of the lamp

Electronic ballasts are superior - they are more energy efficient and have no flickering or hum etc. Lamp life with them is up to 2 times the life stated on the lamp. Use this type if possible

Magnetic ballasts are less efficient and may have flickering issues etc. They are way cheaper than electronic. I happened to have one at hand so I used it

Lamps should be used with ballasts of the correct watts. Too large or too small ballast will overheat the lamp or itself and shorten the lamp life. The lamp size is written on the ballast

On some ballasts there is a range of lamp watts. Most PL ballasts are actually designed for the highest lamp in the range. They will give max efficiency and lamp life with this lamp. The lamps in the lower end of the range often get overpowered with about the same power as larger lamps so just use the larger lamps instead. For example on 5 - 11 w ballast 9 and 11 (and probably 10) lamps are ok and 5 and 7 overheat. On 10 - 13 w ballast only the 13 w lamp is ok

Step 3: Open the Fixture

Swich power off

Open it and remove the lamps

For safety and for the experience (you will need it somewhere in the future) treat the thing as if it is powered on

- Work with isolated tools
- Do not touch the ends of the wires
- Have your shoes on and stand on isolating material

Step 4: Release the Tray

Most fixtures of this type have a metallic tray to which everything is mounted. In open fixtures you just open it and the components are left inside. Sometimes the fixture itself acts as the tray and is mounted straight to the ceiling.

Release the tray

Not all fixtures have something for the tray to hang on like this one

Check the strips before you hang the tray on them

Step 5: Take Off the Tray

Disconnect the wires and isolate them

If the fixture is grounded disconnect the ground wire first. This way if you touch a wire with voltage and the metal of the fixture at the same time you are less likely to get electrocuted

Take off the tray

Step 6: Disconnect the Existing Components

Disconnect the existing components from the source and relocate them on the tray if needed

If you disconnected the capacitor discharge it by touching its wires to each other. A spark may appear - this is normal

Step 7: Mount the New Ballast and Install Wires

Install the new ballast

Install wires

I used wire of the type used to connect smoke detectors. It is not really rated to 240 volt but it works fine. Any wire with plastic that looks thick enough will work (electricity will break through thin plastic and make short circuit). Conductor thickness is not an issue as the currents are very small

Install the wire in a way so it does not touch sharp edges of metal and screw threads and the ballast (it heats to high temperatures when working)

Step 8: Wire the New Ballast

There is a drawing on the ballast how to connect it. Key for the letters :

L / P / wave - is called Live. It is the wire with 240 or 110 volt on it. It is brown in most new installations around the world / black in the US / blue in most installations in Israel / red in many old installations in Israel

N / 0 - is called Neutral. It is the wire with 0 volt on it. It is blue in most new installations around the world / white in the US / black in most installations in Israel

E / reversed tree - is called Earth. It is another wire with 0 volt on it but with different task. If present it should be connected to the metallic tray of the fixture (and only to it). It is green or green / yellow striped in most installations around the world and white in some very old installations in Israel

Standard magnetic ballasts are all connected the same way. Connect Neutral to one pin of the lamp. Connect wire from other pin of the lamp to one entry of the ballast. Connect the other entry of the ballast to Live.

In some ballasts 2 entries are marked as L and P. In this case the rule is : connect the lamp as shown and then connect Live to the other entry - NOT the one with the lamp

In some ballasts there is capacitor shown on the Live connection and a wire that bypasses it. This means the capacitor is optional. We will connect Live straight to the ballast without capacitor in the way (and connect another capacitor another way)

I used one of the 36 w ballasts as a connection point for the wires (instead of a terminal block)

Be sure to connect the wires to 2 entries (and not both to one) on the 9 w ballast. Connecting the lamp without a ballast in the path of the current will blow it

Connect the power wire to the source

Step 9: The Capacitor

The capacitor is connected in addition to the light. It does not affect the work or performance of the light. It does affect the amount of energy the light uses

In 240 v / 50 hz fluorescent lights the capacitor is 4 uF for each 36 watt lamp. In other volts and frequencies this may be different. It can be found out by dividing the capacitor found in one fixture by the sum watts of the fixture. For example here we have 8 uF capacitor in 72 watt fixture which is equal to 4 uF / 36 w

Now we use the same rule to match the new capacitor. Here the light is 9 watt so 1 uF is what we need

Any capacitor of the correct size and designed for continuous operation on the given voltage is ok

I did not have one so I just disconnected it (0 uF is close to 1 uF. 8 uF is not). If you dont have the correct capacitor connect the closest larger or smaller thing you can find

Lamps with electronic ballasts dont need capacitros at all unless stated otherwise on the ballast. Just disconnect all of them

Have a look at the extra explanations on capacitors in the end of the instructable

Step 10: Connect the Lamp

Install mounts for the lamp

Do not use plastics as UV and heat emitted from the lamp will destruct them

Do not use metallic objects with large contact area with the lamp as they may cause light output loss over time (they affect the discharge in the lamp with their capacitance)

You want the lamp to move freely in the mounts

Connect the wires to the lamp pins

Try to avoid terminals of colors other than black if you want the fixture to live long. All plastics except black destruct from the UV light emitted from the lamp. Heat is not an issue as the base of the lamp is not too hot.

Step 11: Install It

Connect the tray to the 'arrows' if present

Connect the wires (see color scheme in Wire the new ballast step)

Bend the wires so they dont get caught by the sharp edges of the metal and dont touch the active ballast

Close the tray and the fixture

Step 12: Done !

Thats how rooms should be lit !

Step 13: Problems

No light - Any missing connection ?

Lamp flickering or cannot start - Are both 9 w and 36 w ballasts connected in series ? connect only the 9 w ballast

Light flicker - sometimes almost unnoticable - Change to lower watt lamp in the range printed on the ballast or change to alittle larger ballast

Lamp bright and overheats - Is the 36 w ballast connected ? connect the correct one

Lamp blows with a flash or explodes - Is the lamp connected straight to the source without ballast at all ? The wires go to 2 entries and not both wires to one on the 9 w ballast. Check isolation of wires and that the ballast is ok. In fixtures with earth connection the ballast must be on the Live and not the Neutral. After fixed everything connect a 100 w incandescent instead of the PL. it should light way dimmer than normal. If it lights normal something is wrong

Breaker or RCD trips - Check for incorrect connections (like capacitor connected to Earth instead of Neutral) and for damaged isolation. Check the ballast for leakage with multimeter. Try to disconnect the capacitor

Step 14: Ballasts

Fluorescent lamps (including PL and CFL) and most high power discharge lamps (like used in outdoor lighting) need a spike of high voltage to start and current limitation while they work. Fluorescents need to warm up for about a second before they start

This is done by the ballast. Sometimes a second component called starter is used in combination with the ballast to make the voltage spike. Most starters are a small neon discharge lamp with mechanical switch inside

Ballasts can be electronic (electronic circuit) or magnetic (a device similar to transformer which works on the same principle)

Normal electronic ballasts are superior to magnetic ones - They are more efficient. They dont let the lamp flicker. Lamps often live with them nearly twice their nomal lifetime

The magnetic ballasts are older technology that is still in use and are way cheaper

Some systems use magnetic ballast with electronic (like PulseStarter) or thermal relay (like Perfektstart) starter. They have better reliability and lamp life time but everything else is same as standard magnetic systems with neon discharge starter

Step 15: CFL Vs PL

In a CFL the ballast is fully elecronic. the circuit is located in the plastic part of the lamp. This is more convenient and easier to use but this makes most CFL problems . .

Energy and pollution take place in CFL production. When a blown CFL is trashed the electronic circuit is trashed too and energy and pollution are required to make a new one

Electronics dont stand heat well. Thats why CFLs dont work well in closed or recessed fixtures

The lamp is designed to last few thousand hours and the electronics are not built to last way more. Extremely low quality electronics are used in CFLs. They often fail before the lamp part reaches normal end of life. Sometimes they shorten its life actively by starting the lamp without warming it up first

The lamp is larger and heavier

The lamp is more expensive

Step 16: The Capacitor (continued)

Magnetic ballasts use inactive power (in addition to the 'real' active power the lamp itself uses). They pull energy from the electicity source and then push it back in alittle later. The energy returned is useless for the system and conflicts with the energy given by the actual source. The source needs to both supply that extra power and dissipate it when it returns. This energy is just wasted without doing any useful task

The capacitor uses inactive power too. The magic is in that the capacitor takes energy exactly when the ballast releases it and the other way around. This way they complement each others needs for inactive power and free the source from supplying this energy or fighting it when it comes back

Thats why capacitor and lamp need to match in size - to use exactly the same amount of inactive power and cancel each other. Too small capacitor will not give all the power the ballast needs. Too large capacitor will create the same problem but in the opposite direction

With approximated but inexact capacitor the inactive power used from the system is the remains of what is left after the capacitor (or the extra created by the capacitor if it is too large). An approximation from either direction is better than nothing

Capacitors dont have to be individual. When converting large amounts of fixtures that work on the same circuit (or when just removing lamps and starters without altering the fixtures) disconnect capacitors in some of the fixtures so that sum of all capacitors and sum of all lamps together will match each other

- If we do this mod in 32 (or any number close to 32) fixtures of the type shown we leave capacitors connected in 4 of them and disconnect in all the others
- If we just remove one 36 w lamp from each fixture we disconnect the capacitors in 16 fixtures
- If we convert one fixture to 13 w (and not 9 w) we need approximately 1.5 uF capacitor for this fixture. If we dont have one we can use 1 or 2 uF capacitor (its good approximation) or make exactly 1.5 uF with 3 x 1 uF capacitors
- If we convert 32 fixtures to 13 w we leave 6 capacitors connected

The choice of exact fixtures where to leave the capacitors connected is not important (unless the system uses 3 Live sources (3 phases). This is quite rare)

Connecting two capacitors in series halfs the size and connecting them in parallel doubles it (connecting any number in parallel is sum of all of them)

People throw away lots of electrical fans in the end of the summer. Among all other things you can do with them there is a 1 - 2 uF capacitor in each and it is excellent for use here. It is usually black rectangular box found inside the motor part


Karel Jansens made it! (author)2008-09-27

Actually, you're quite right in step three to advize to work as if the power is still on. Unless you're 1,000% certain the light switch is of the bipolar type (and no, I don't mean it gets depressive occasionally!), simply turning the power off (as you suggest) might very well leave part of the circuit under -- lethal -- power. "Take out circuit breaker" seems like a much more sound first step.

whiskthecat made it! (author)whiskthecat2012-07-03

Chill out it's only 120V, not gonna kill you if you aren't soaking wet.

DeanB25 made it! (author)DeanB252016-01-17

''only 120 VOLTS ac'' will kill you DEAD.

the typical service to your dorm room lighting circuit is 20 amps at 120 volts.

AT MINIMUM it would be 15 amps, it only takes 1 tenth of ONE amp to stop a human heart at 120 volts. If it goes through your body in a certain way to hit your nerves that control the heart is the stickler, were usually lucky when it doesnt get ya.

I'm an industrial electrician, have brushed up against 277 volts with the back of one hand, and let me tell ya, the WORST i've ever felt was working on a light switch in a house at 120 volts.

whiskthecat made it! (author)whiskthecat2016-01-17

Like I said, soaking wet. For 1/10 of an Amp to be flowing through your body at 120v you would have to be so conductive that touching a AA battery would provide you with a tangible shock.

joinaqd made it! (author)2009-01-08

you are a nolifer seriously get a life...

whiskthecat made it! (author)whiskthecat2012-12-06

You do realize that you are spending your time commenting on the insignificance of someone else's comment?

richms made it! (author)2008-09-27

The problem with the PL fluorescents which doesn't happen in the CFLs is the bad flicker they have from operating on line frequency directly. This is proven to cause fatigue in many people. The 2 pin PL's are only able to be driven reliably from a magnetic ballast since they have a starter built into the lamp.

11010010110 made it! (author)110100101102008-10-01

Electronic solutions Use 4 pin PL or open the base and connect 2 wires instead of the starter Some electronic ballasts play nice with 2 pin PLs without any hacking Use a CFL Use a CFL ballast with the PL .You need to open the PL and change the starter to the capacitor from the CFL. Ballast from bad CFL (if the ballast is ok) can be used. I have not tried it Magnetic solutions Some PLs flicker more and some less - depends on quality / age / type of phosphor (daylight / cw / etc) To me the cool white lamps seem to have better phosphor than other colors and flicker less Fluorescent lamps flicker less when they are little overpowered. Try to change the ballast up or the lamp down to make 1 - 2 watt mismatch (not enough to make trouble). Sometimes just changing to another ballast of the same watt helps (ballasts are not exactly the same) When operating more than one PL on the same circuit : - Running them in series off one ballast seems to make way more flicker - When running on separate ballast you may add capacitor in series with one of them to change the phase of flickering. This reduces the sum flickering in the room. The value of capacitor is sometimes written on the ballast. Use only capacitor of the exact value - approximations are not tolerated as in PFC capacitors DC solution You can run the PL on DC. I dont recommend this - fluorescents dont like DC

12V made it! (author)12V2009-05-13

if the cfl dies suddenly it is usually a bad ballast. if the cfl is dim the cap on the ballast is bad(but can be repaired) if the cfl strobes and flashes it is a bad tube and the ballast is ok. if the cfl dosen't turn on one day the gas has got out of the tube. if the tube lights dimly the tube is usually dead and the ballast will work (the ballast may burnout if left on for more than 3mintes)

vikyngo made it! (author)2009-03-12

Don't want to sound rude, but I think your mods are bit silly. The original lamps have very high efficiency. In you want to improve them, just change the ballast (not add another one), change the tubes for better ones or also choose them with lower power output. The little 9w lamp is just the same technology as the old ones.

11010010110 made it! (author)110100101102009-03-13

i dont want to sound like you but if you would read this instructable BEFORE you comment on it you'd see that its exactly about changing the ballast and the tubes

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