Fluorescent Lighting - Myth or Truth

[manuellynch]

We see quite a few people in car parks/parking garages remove one fluorescent tube from a two (2) bulb fixture thinking that it saves energy. Can you answer the poll on what you think happens? Just curious on what people know or can add.

[Erik Sine]

It's going to depend on the ballast

[Camelot Sign]

An electronic ballast with parallel wiring provides each lamp with whatever current they need to run. If one lamp were to burn out or be removed it shouldn't effect the rest of the lamps life or operation. Will it cut the power used in half if one lamp of a 2 lamp fixture were removed? No it won't. There is still power required by the ballast to run the remaining lamp. Power usage may be reduced but not by much really. The only thing that really happens is that the light output of the fixture has been cut in half. If this is done with all of the fixtures in a parking garage you will have a dimmly lit garage. This also makes it a bit more dramatic light wise if that one lamp in the fixture goes out and that area is even darker. If the ballast is a magnetic or series wired ballast both lamps would be out or the ballast would still attempt to start both lamps and that would reduce the life of the remaining lamp and could shorten the life of the ballast.

[Brian]

Alright Manuel my friend just were are you going with this...fess up

[manuellynch]

Alright Manuel my friend just were are you going with this...fess up

Honestly Brian - no particular direction this time.

Jim Richards from UL one time mentioned to me that a fluoro ballast will overheat when one tube is gone and it will cause the ballast to eventually shut off due to overheating.

Gregory at Absolute Signs in California is heavily into maintenance and he tells me that the common mistake people make is not to replace all the bulbs that the ballast is driving.

Saraendi, the electrician on the wharf here in Auckland NZ, tells me that you wont be consuming less power by removing a bulb and it shortens the lifetime of the ballast.

And then I remember from my days in the CCFL world that the wrong load or a varying load on a ballast can cause problems on the lamps and on the ballast.

So this is a proverbial grey area and I thought it would be good for people to share knowledge.

We have heard of some great knew energy saving smart ballasts but from my understanding they will shorten the lifetime of the fluoro tubes. Seems to be less of a science than that of neon - or at least that is my view.

I am heavily involved in other forums that discuss the effects of mercury on underwater plant life - collective boards sharing information is a great way to rapidly learn about the environment we live in.

I just wanted to collectively learn from each others knowledge.

[Erik Sine]

I tested my two lamp T8's I use for shop lighting. Each fixture puts out 60 watts, with one lamp it cuts down to 40 watts.

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Edited April 30, 2010 by Westcoast Sign Guy
Typo

[manuellynch]

I tested my two lamp T8's I use for shop lighting. Each fixture puts out 60 watts, with one lamp it cuts down to 48 watts.

Sent from my iPhone using Tapatalk

So 50% less light output and you save 20% power! Thank you Erik - sometimes doing it makes the world understand.

[Erik Sine]

Sorry had a typo, it was 40 watts, had a 8 in there by accident. So it's 33%

I swapped out my typical Home Depot T12 Fixtures with GE H series Ballasts and their T8 lamps. The efficiency PF on these are 1.0, so their pretty efficient.

I did a huge change out with Petco stores a while back, and at some of the stores they had 3 and 4 lamp ballasts where we did complete retrofits from T12 to T8 and someone had taken out 1 to 2 lamps per fixture and maybe it was to save energy as you said. These fixtures were on for years with very little sign of lamp or ballast wear.

What a shame I thought at the time, ripping out these fully functioning components in good condition (ballasts and lamps), I always thought it would have been a good thought to give them to someone who could use them, maybe somewhere off to a third world.

[Camelot Sign]

Fluorescent lighting does seem to be a grey area Manuel.

Speaking only of parallel wired electronic ballasts, if the one lamp that goes out does not reduce the remaining lamp load to below the minimum footage recommended for that ballast the ballast will run just fine without overheating. Now if that lamp going out takes the remaining load below the minimum footage the life of the ballast will be shortened. If the sign is dim and only a couple of lamps are lit it is better to turn it off and at least save the ballast and at least the expense of replacing the ballast.

I get loading questions for fluorescent ballasts both magnetic and electronic, T12 and T8, and they appear to be the same questions from different people.

Another point to remember is that when using an electronic ballast with only one wire going from the ballast to the socket, connect that wire to BOTH wires of the socket and if a jumper is needed to get to the next socket use another wire. Too many times the ballast wire is connected to one wire on the socket and the other is used to jump to the next. This sends all of the current for both lamps through the first lamp and burns it our very quickly.

I'll stop typing now...

Dave

[YYZ]

It's important to note that sign ballasts and light fixture ballasts are not the same.

Sign ballast are made to operate with different numbers or lamps and have switching circuitry to adjust to the load. A light fixture ballast made for 2 x 48" lamps has to be used with 2 x 48" lamps, period.

[Erik Sine]

Just got off the phone with GE for their ballasts I used during the retrofits I did for PETCO's on T12 to T8's, whcih included the state rebate program. I did 2 lamp and 4 lamp retrofits.

I also used these for my shop light switchouts.

According to them and their ballast label, no extra load will be put on the ballast or lamps if other lamps in the fixture go out or are taken out.

Below is the wiring diagram for a two lamp fixture ballast,

[HansonSigns]

This was really interesting - I acutally learned something! Thanks for the great info, all!

[TecnoluxMan]

Can this poll be edited?

[TecnoluxMan]

This was really interesting - I acutally learned something! Thanks for the great info, all!

Me too>>>>I thought small lamp fixtures would be affected by missin glamps, Its probaby safe to say because I have the thought of inductive ballasts in my head

[imanut]

Just got off the phone with GE for their ballasts I used during the retrofits I did for PETCO's on T12 to T8's, whcih included the state rebate program. I did 2 lamp and 4 lamp retrofits.

I also used these for my shop light switchouts.

According to them and their ballast label, no extra load will be put on the ballast or lamps if other lamps in the fixture go out or are taken out.

Below is the wiring diagram for a two lamp fixture ballast,

I think that differentiation must be made between electronic and core/coil ballasts. Also the difference between HO and bipin, or single pin ballasts. The GE ballast that Erik shows is clearly not for HO use. In a multilamp ballast - if a lamp goes andthe rest are less than full on --- it has to do damage to the lamps and ballast...........imho.

gn

[Erik Sine]

I thought we were all on the same page talking light fixtures.

[imanut]

?? I was having a private conversation with myself. Sorry, didn't mean to interrupt.

[manuellynch]

So one of the electricians I spoke with says that when a new operations or facilities management person takes over they always try something like removing one tube.

He did say that the glass on the bulb does act like a reflector when the two lamps are on so he believes based on what he has seen is that only one bulb on is actually less than 50% of the light output.

He is going to be doing a test in a Parking Garage, Elevator, and Cabinet Sign. He is also doing a 2nd test comparing it to our AoTuroaLED Retrofit kits. He is interested to see what happens to our LED light output when he cuts off 1/2 the LEDs - he wants to show that power does go down vs fluorescent where there is not a direct proportion.

He also said that he was sure that driving our LED drivers at even lower power or fewer LEDs will not hurt the driver but actually increase its lifetime dramatically.

[manuellynch]

Wow - just learned that there is no easy way to tell the difference between magnetic and electronic ballast - best way is by weight - is that true?

[fishing nut]

Wow - just learned that there is no easy way to tell the difference between magnetic and electronic ballast - best way is by weight - is that true?

Size, label, wires coming out. manufacturer.

[Brian]

Wow - just learned that there is no easy way to tell the difference between magnetic and electronic ballast - best way is by weight - is that true?

when all else fails read the label

[bigclive]

With a traditional choke based two tube fluorescent fitting with a choke per lamp, removing one lamp will effectively half the power drawn, but if there is a power factor correction capacitor designed to compensate for the full two lamp load then you may end up with a leading power factor. That would only be an issue if there were a very large number of fittings with one tube removed, and the overall power factor of other loads in the premises was near unity.

With an electronic two tube ballast I would expect the power drawn to roughly halve and if anything the ballast would run cooler.

A situation that will cause issues is when a lamp fails in a traditional choke and starter fitting, and the starter welds shut leaving the ends of the tube glowing. In that instance the dead tube may be drawing more power than if it was lit, the ballast will be hotter than normal and the lamp-holder may suffer thermal damage too.

[Fred]

b

Edited May 24, 2010 by Fred

[LiteGirl]

c

[bigclive]

Neither. The efficiency rating of fluorescents is "A".