2x 40w Fluoro's in Series. How to..

Why not just Tee off one of the working feeds to the fluoro unit that had the bad feed?

GA

That would appear to be a) the best idea b) the easiest idea c) sadly being totally ignored here!!

Assuming that the frame is well earthed (otherwise add an earth connection) a simple piece of two wire mains cable from the input of a working light to the problem one, after removing the supply wire(s) that are shorted.

If the neutral is still good, just removing the earthed phase wire and connecting the fitting to a "good" phase should actually be enough!! A single piece of insulated cable will do it!....

You may have "mislead" them all because you did not specify a "mains" feed to the complete circuitry of the Fluro that has a shorted mains input. Now they want to redesign a fitting with starter....totally unneeded, assuming the OP posted correctly of course!!

Though personally I find it obvious what you meant.....but thats just me I guess!!

Where are we going wrong that we are being ignored?

Just to explain how these work for you Andy and to advise you that not everyone is as stupid as you so often appear to presume.

The ballasts are located remotely from the display cabinet. One live wire comes from each ballast to the display cabinet (which, I repeat, is not adjacent to the ballasts). They then go to each individual tube and starter and then on to a single shared neutral.

There is no live feed in the display cabinet, and the OP has pointed out that he cannot get one there. That is why he is attempting to alter the circuitry to utilise what is already there. As with most of these display cabinets, there will be nowhere to fit a ballast near the tubes, that's why they are located elsewhere.

The OP has stated that one of the wires going from a ballast to a tube has a short circuit to earth. He cannot get another wire from the ballast area to the tube.

With that information it is reasonably obvious that getting another feed to the tubes is either not possible or not easy. There is nothing wrong with the live feed to the ballast.

I hope that explanation is simple enough for you to understand.

I have only used lighting where the ballast was part of the fitting. I did not know there were other methods with remote ballasts.

It was also not mentioned clearly either.

He has a real problem then!!!

Some special electrics are needed to do what he wants.

He should try it away from the customer in his workshop.....if there are half voltage tubes available, it might be possible....it may even be possible with one starter and two tubes in series.....never really thought about it though....

Here in Europe we could order 2 x 115V tubes and maybe cobble something together....but if he is already at 115V..........

In his place I might consider even using say 2 x 40W tubes on a "camping 12 volt fluorescent circuit" and install a "meaty" 12 power supply instead of the ballast.....no starter needed and the tubes lights instantly....don't even need to warm the filaments up either!!!

24 volt version (truck?) would be even better.....less current!

Look here for both:-

12 and 24 Fluorescent Ballast for 40 W Tubes

Swapping the polarity of the tube once a week will get a longer life out of it.....though they will probably run a year or so without doing that....some circuits change polarity automatically.

I'll have a further think about it regarding mains......but the 12 or 24 volt DC version would work just fine and get him out of trouble.....I have similar ones in my caravan for many years now. I am not alone!!

Do Not forget "GIGO". I expect you already know what it means!!

Remember, if important details are glossed over, they may not be understood by all here.....no mention was made of remote ballasts.....

PS when did I say anyone was stupid? I cannot find it anywhere in the blog. Please be so kind as to draw my attention to it.

PPS You are both OVER sensitive and downright rude. NOW THAT IS A FACT!!!

That is patently obvious to all here........try quietening down.....

The information was all there for you if you had bothered to read it first.

The OPs first post was pretty self explanatory. While he didn't say that the ballasts were remote, it should have been obvious to anyone with electrical knowledge.

The guy is an electrician, if he could have simply replaced the feed he would have done so, give him some credit for a bit of nous.

The only one who glossed over the important details was you.

His post # 4 told you he is located in Australia on 240v. Did you miss that?

His post #7 told you emphatically that the ballasts are remote from the tubes. Did you miss that too?

How many times is he required to provide the facts before you manage to interpret them?

Low voltage DC ballasts still require at least 2 wires from the ballast, he doesn't have 2 wires. Had you read your own link to low voltage ballasts, you would have seen that those ones actually require 4 wires from the ballast.

As for me being rude.. Going by some of your recent posts on other threads, I'm happy to let others judge who the rudest person on this forum is.

I answered the original question, with he original information.....which was incomplete.

Now did you understand that?

What do you think of the DC idea?

Pretty good eh?

You can't put 2 fluorescent tubes in parallel across one ballast because only one will light. This is due to the fact that once one tube has begun conduction, there is insufficient voltage drop across the other tube to force it into conduction also.

International Rectifier make a product(IR2167) that will allow you to do this but its associated circuitry requirements are horrendous. Parallel quick start ballasts can do it but you will need more wires than you have available.

You don't say where you are or what your mains voltage is but I have been told that even 20w series tubes don't work so well on 110v because the voltage is too low to maintain the arc discharge. US based respondents can confirm or deny this for you.

The circuit for 2 x series fluorescent tubes is quite simple, but I'm not sure that you can do it with 40 watt tubes. The reason is that you require a pair of series starters (designated FS2, they have a lower breakover voltage) which, as far as I am aware, are only made for maximum 20 watt tubes, again because of the discharge voltage requirements of 2 tubes in series. You could try it with those starters and you may be lucky, or maybe solid state starters will work. If only one tube lights with the series setup, try rotating one starter 180° as that sometimes works.

Where are the starters located? If they are with the ballasts then a little bit of circuit manipulation and the placement of one starter adjacent to a tube will get you 2 spare wires in the loom to replace the faulty one and keep the single tube per ballast setup.

If the starters are already located adjacent to the tubes, then you're basically screwed.

I'm in Australia on 240v. I can get dual 18w T8 series lights that work but 36w won't

I've tried that but 1x 40 w ballast won't ignite 2x 40w tubes, so I tried putting 2 ballast in parallel with 1 starter then 2 starters then 2 series starters then switch to wiring tubes in series then change ballast with 80w choke. Can only ever get 1 tube going.

Did you use the correct wiring sequence for series tubes?

You haven't said where your starters are located.

The 5 ballasts are under the displays. The 5 feeds + neutral go up thru the side wall of another display cabinet then run thru a sealed top before dropping out into the display I'm working on. That's why I can't pull a new cable or fix the existing. Each feed goes to one light tombstone which has the built in starter. Has anyone every seen 40w or 36w tubes in series?

Are these 40W lamps single or two pin ended? How many wires and of what color get to each of the good ones ?

I'm asking because if each lamp receives for example one yellow and two blues or reds, the O.P. might keep the yellow as common for two lamps and separate the red ones or blue ones, one for each of the two lamps.

Are you sure the fault is in the wiring (and not a faulty ballast)?

Are the tubes T12 or T8?

It appears that in some countries the T12 are "going out of fashion!"

See here:-

T12 versus T8

It is not all that difficult to get 2 fluoro tube to run off one ballast, although I must admit that I have only ever done it with 2 x 20W tubes. Note also that I am here in 240VAC land, and I don't know that this works at lower voltages.

The trick is to wire the tubes in series, using a ballast which has a power rating equal to the sum of the two tubes ie a 40W ballast is needed to run the 2 x 20W tubes. The other important bit is that you have to use 120V starters (and yes, you need tubes with 2 pins at each end). I know this sound a bit odd, but it does work. It was shown to me by an old guy who had made a living in the sign industry where apparently saving every red cent is important to staying in business.

It is quite entertaining watching this setup start up because often the tube flick on alternately before they both light up.

I am led to understand that fluoro tubes have an odd resistance characteristic that means that wiring them in series does not mean double the series resistance of individual two tubes - something about the resistance of the tube being dependant on the voltage across it but I never did get to the bottom of that. I can confirm though, that the 2 x 20W setup draws pretty much the same line current as 1 x 40W tube.

I was thinking that something on those lines would work, it is really nice to have the definitive answer that it can be done....

I am sure that I am not alone either!!

GA

I live in Europe where the voltage is 220V (close to 240V). Some years ago I measured the voltage on 20W and 40W tubes and the values were 60V and 120V. The remaining voltage (160V or 100V) is present on the ballast which has the proper inductance to limit the current to the needed value.

When you put two tubes in series the voltage drop on each of them is the same - that's why two 20W tubes will work OK (using a 40W ballast) but if you try to put in series two 40W tubes the available voltage is not enough. The needed voltage would be some 340V (2x120+100) to keep the same voltages on the tubes and on the ballast, so to keep the same current. The only solution in this case is to use (if possible) a small transformer at the ballast place (240V input, 340V output, rated for 80W) and an 80W ballast (or two 40W ballasts in parallel).

If you try to put two tubes in parallel only one will have the chance to ignite - the moment this happens the starter of the other one will stop working and the tube will never ignite.

I'm not sure if you can change the bulbs to a different type, but if so, you can wire the two in parallel (so one isn't dependent on the other) and use LED tubes. The price has come down on the tubes and they're pretty reliable. Also, you can choose the color you want.

Thanks everyone for your thoughts but I've tried every way possible to ignite 2x 40w tubes without any success. I thought there may have been a special ballast available that my wholesale didn't know about but someone may have. To answer a few questions, I've been any electrician for 18years and I seen 18w tubes in series plus repaired a few " to many " but I was trying to find an easy way out because of what's involved in getting a new line up. Drilling stainless steel and running stainless tubing will be a costly process for my client. If I could change the tubes to LED that would have been easy but the colour of the tubes have a purple tint to it so that the meat looks good. I've tried getting LED but they can't match the colour spectrum. They're not available in Australia so I've been told from 4 wholesalers. I've thought of a solution. Use 1 of the good feeds as a hard active to power a twin T8 electronic ballast which I'll get a stainless cover made for. Again thanks to all.

Sounds like the way to go mate. Hat off for your perseverance too!

You find some strange service-hostile wiring practices in appliances. Makes you wonder why it was built the way it was.

LED tubes come in all color temps. A blue light is probably around 6500K or so. Here's a link to a place on ebay, where you can buy different color temp LED tubes. http://www.ebay.com/itm/G13-4FT-20W-3000K-4000K-6500K-CLR-STR-MLK-T8-Fluorescent-Replacement-LED-Tube-/291229346937?pt=LH_DefaultDomain_0&var=590380848451&hash=item43ce9f2c79

I think this may be the best way to go, without doing some major work on the meat cases.

I don't want to be negative, but finding the right colour temperature may be a problem. Though I have never looked for one for displaying meat, so probably one with a red "cast" may work.....

While doing some lighting tor a hairdressing salon some years ago, we did not find a single LED one that gave the wished colour for the owner.....as the halogen lights did. He stayed with Halogen.

I still feel that using the same original tubes is the best method, especially colour wise and driving them via a 24 volt camping ballast, using the cables that are still ok. A meaty 24 volt power supply (Switched mode for cool and efficient usage), would be best, but 12 volt versions are widely available too.....

Also far safer for the user than mains voltages in the display cabinet, not forgetting the normal "striking" voltage that will be much higher than that.....

Halogen lights are difficult to try to mimic, since they have a wide spectrum of light. Fluorescent tubes have spikes in the spectrum. LED's are kind of spikey, so it may be much easier to get a good match. I agree that it's very difficult to try to reproduce either a Halogen or tungsten bulb with and LED.

....and I thought it was just me and that Lady salon owner......I wasted a LOT of time trying to save on her electricity costs!!!

Maybe the LED people need to concentrate on improving the colour matching to older technology more!

Thanks for your post.

Take a look at the light spectrum on these charts. https://www.google.com/search?q=halogen+vs+led+light+spectrum&biw=1920&bih=945&tbm=isch&tbo=u&source=univ&sa=X&ei=xyRAVbWcOcSqNtb5gJgF&ved=0CCMQsAQ#imgrc=rdAVHpH7szCbBM%253A%3B4T_3Ty4kKR8QSM%3Bhttp%253A%252F%252Fhousecraft.ca%252Fwp-content%252Fuploads%252F2012%252F09%252Fspectral_responses2.png%3Bhttp%253A%252F%252Fwww.polyphasicsociety.com%252Fpolyphasic-sleep%252Fadaptation%252Fnight-lighting%252F%3B685%3B392

I have a feeling the salon owner liked the warm light (stronger reds), which makes skin look pink and warm.

From an economic standpoint, LED's make more sense than halogens, but for aesthetics, halogen is hard to beat.

Years ago, I owned a jewelry store. We had some pretty fine quality gemstones and diamonds. The halogen light typically did the best job of making the jewelry look good, but we also needed some cool white light for the darker blue and purple gemstones. High quality sapphires and tanzanite looked great under cool white light - it made the colors pop!

I feel that possibly this light spectrum stuff is a whole science on its own.....

I know that I was blown away at how difficult it was to (not!) make that salon owner happy!!

My last reply was directed at autobroker. LED not available for meat displays in Australia.