Relamping the shop

On 9/19/2018 3:07 PM, Terry Coombs wrote: > A few months ago we had a power surge or something , blew out all the electronic ballasts in my shop fluorescent lights . I've been limping along ... Today I received via the USPS a box containing 10 four foot LED tubes ... six of which are now installed in my fixtures and lighting my shop . Simple changes to the fixtures , hot lead to one end and neutral to the other (both pins) and bang we got light ! A lot brighter and a different color/temperature but that I can get used to . I got the clear tubes , upon reflection I might have gone diffused ... a piece of scotch tape will test that . Bottom line is for under 5 bucks a tube , they don't cost that much more than a fluorescent tube and they'll save me some bucks down the road in lower energy bills . And I used the fixtures I already had . >

I've got 8 foot dual tube cans in my shop, and the florescent tubes work just fine. However, my last trip over to a local store found me buying what may well be the last case they will ever stock.

I expect I'll be forced to replace or rewire all my cans eventually myself, but none of the places I checked had LED tubes at anywhere near the price yours cost. Care to share your source. Also, let us know how they do after a few years. I replaced all the bulbs in my office and machine room with Leeson LED bulbs and the first one died within a few months. I think I've more than half, and I only got them a couple years ago. I originally got a lot more than I would need, and I am down to just one or two spares.

Needless to say I'll be looking for another brand of LED bulbs next time.

I did a quick search on 8 foot LED tubes, and they are available from a number of sources. Did not check prices as I expect they will cost less when you need them.

Dan

I replaced the fluorescents in my shop with a case of 20 frosted 6500K

40W 8 footers from this guy last Feb.

One half of one lamp failed within a few weeks, but that's a minor complaint compared to the increased light, decrease in the electric bill, and elimination of the magnetic ballast buzz.

The LED 8-footers available locally were drop-in replacements for the fluorescent tubes, i.e., require the ballast to operate. Stupid. The lamps I purchased connect directly across the line. It took no more than a couple hours to remove the magnetic ballasts and rewire the 10 fixtures.

Took a little longer to get used to the color change. Now the places that still have the CW fluorescents look dingy to me.

We replaced the 4 foot T8's in my wife's studio about a year ago with

10 lamps from this ebay seller. No failures to date.

It seem prices have stabilized or gone up a bit since my two purchases.

Fluorescent Tube Light Bulb G13 T8 lamp fixture

Maybe not so stupid. The 'require ballast' lamps get about 24V of excitation, which means seven or eight LED diodes in a series string, with other strings in parallel. The 'full voltage' get 240V, so that's seventy or eighty in series.

The failure rate for a series string of seven is 0.1 of the rate for a string of 70. And, one string failing doesn't stop the other parallel strings from making light.

Best practice for designing LED fixtures is not compatible with reusing the fluorescent fixtures unballasted OR with the original fluorescent ballasts. GE makes LED fluorescent-tube-shaped lamps labeled "Use only with General Electric LED21T8 DR/.... LED driver"

Where do you get 24V? A standard ballast for 8 foot F96T12 lamps outputs 750V for starting the lamp and 425mA operating. That implies about 175V across the 75W lamp once it's running. Now, in addition to the internal LED driver(s) in the lamp, you have a point of failure, the ballast, that's not doing anything useful. I'll bet I've spent as much time over the years replacing ballasts as lamps. I'd rather spend the time up-front pulling them out.

pretty bright and tend to glare a bit . I tested it , and a strip of (frosted) scotch tape over the center of the clear side of the bulb is just about right . These are 6000K light temp LEDs , taking a bit to get used to after having less-than-enough light that was a lot more "yellow" .

I ADORE the whiter LEDs and hated the piss-yellow incan color, so it was an easy swap for me. I sure like the newer pricing on LED fluor replacement strips but haven't partaken yet.

The LEDs are more efficient, but the ballast still chokes current at circa 425 mA. So, the voltage is lower for LEDs than for tubes. My '24V' number is only order-of-magnitude.

But, it IS buffering the LEDs from voltage spikes, without the power-wasting resistors used in some lamp-replace series strings. The starter-boost is a complex part of the ballast, but isn't required for the LEDs; if it fails, you'll never notice. The 'internal LED drivers' in the one lamp I dissected, were... only rectifiers to prevent reverse voltage.

I have read in more than one place that dimmable LED lamps can better handle power fluctuations. Where I live we have 250 volts most of the time with occasional excursions above and rarely below 250. So I have been installinf only dimmable types. Haven't had any failures yet except for a cheap night light. That wasn't dimmable. Eric

Which means the LED driver in the tube has to deal with a constant current source that can deliver up to 750 volts instead of a well-behaved 120V constant voltage source. Doesn't seem advantageous to me.

The ballast is intentionally designed to develop a 750V spike.

without the power-wasting resistors

I've not seen dropping resistors in the replacement tubes. All I've seen have switching LED drivers. Look at the specs for the LED replacement tubes I pointed to. They run on 100-265VAC or 85-265VAC.

Perhaps for an electronic ballast, not so for a magnetic ballast.

I don't understand. Why would you need to protect an LED from reverse voltage?

A constant current source is ideal for powering LEDs; with the right size LED (or the right multiplicity of paralleled LEDs) that's useful power.

Yes, in order to light the cold tube; but, it does that when the tube is NOT conducting, when that potential 425 mA of current isn't drawn. LEDs without a 'driver' attached will always draw that current.

Do you mean drivers built into the long tubes? I've never seen that.

Look at the specs for the LED

There's different designs, including some with heaters/neon lamps etc.

Reverse voltage can create large (surface) electric fields, and move impurities around. That causes the LED to age, dim prematurely. Forward voltage on the diode never exceeds 3V, because the diode conducts, and that means the surface fields are smaller.

very little but what their masters tell them to say .

So far so good. The contraptions he's posted in the past demonstrate a need to learn how to weld at the very least. He's a dopey slow learner, so if he ever does learn to weld he'll be old like me by then and maybe he'll figure out what a great advantage it is to have a small headlamp on a welding helmet, a headlamp for every other task, bright shop lighting, bright task lighting, and white walls and ceiling.

Same thing you said about me. You're demonstrating your own cognitive limitations.

LOL Who are these "masters?" It's clear that JD has very few fabricating skills, limited imagination, and is a top-posting bozo. His fascination with cordless drills makes me think of how cavemen might have responded to seeing a bag of marbles. His projects might impress the least-mechanically inclined high schoolers, but that's about it. Those are facts. So if you want to insult him, why go beyond the obvious by posting your own delusions?

BTW, if he lived near me I'd offer to teach him some stuff. First thing I'd do is walk him over to my 16" gear-head, and set him up with a big chunk of rubber to turn at high speed while wearing a baggy protective kimona. Then I'd get him onto welding while using "tactile" gloves with all the finger tips cut off. After that maybe set him loose on out of position wrench turning of seized fasteners such that his teeth are in the line of fire. Only after he gets up to speed on all that would I show him how to fast charge his drill batteries using a patch cord into an AC socket.

Your stuff was cute when I first saw it. And I'm generally supportive of kids even if all they're doing is trying. But you have progressed little, and spent too much time being annoying and witless.

Among the many things I've built is an entire aircraft. I could never have gotten any of it done if I'd been too busy uploading pics of Gillian Anderson and insisting that a headlamp was a substitute for good shop lighting. WTF?

And yet you never learned not to top-post on Usenet.

I've lived off-grid. And my welding during that period was powered by inverters and batteries. You are an idiot to pretend you have more skill than old farts like me. I was doing more impressive fabrication when I was 14 than you are now. I was sneaking into my dad's garage when he was at work, and whittling down his puny supply of electrodes, which he was only superficially pissed about. I was cobbling together go carts and mini bikes at the time powered by an old pedal-start washing machine engine. I knew right away that I needed to learn to weld, which is something that seems to have escaped you, along with the fact you could have learned in less time than you've spent yapping online.

Then why are you still doing it, feeb? Less annoying witlessness and more doing and you'd be much farther along. Although I sense you're not very ambitious, and the main goal is to get some attaboys. Good luck with that.

I'm confident you'll keep doing what you "feel like," no matter how dumb it is.

You're a dopey top-poster. You're pigheaded to keep doing it.

Not much design there. In fact, marrying two existing things is generally the opposite of design. Chocolate and peanut butter combinations excepted, of course.

Dopey challenge. I stopped being interested in bicycles about 50 years ago. I found that pretty much any other vehicle expanded my range quite a bit. Especially aircraft, which tend to have more design and fabrication requirements in a single sub-system than you've done in your entire life.

My mistake, it's the somewhat similar looking Lauren Holly, and a crotch shot of Maria Sharapova. Are there drill batteries hiding between her legs? The cat doesn't look impressed at all, time for you to drill-motorize a cardboard box I guess. The point remains, you can use your time to yap or to progress. You've made your choice and I'm happy you're here for me to poop on.

Nobody's surprised that you're proving my point by posting more lameness. Why do you keep adding "free spam" to the group list? Was that something you learned to do in 'puter school?

Sure, but you can't just connect parallel strings of LED's to a constant current source and expect the current in the individual strings will be equal. And if you implement a single string connected directly to the ballast, LEDs that'll operate at 425mA are expensive, require relatively heavy heat sinks, and will present difficult-to-diffuse bright point sources. Approx 30 LED's vs. 196 in the replacement tubes I purchased.

Yet, it's done all the time. A 'nine-LED' flashlight with three AAA cells has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common, also. Sometimes resistors are added to each string, but not always.