mag ballasts with 20 connections?? I've never seen anything like that here, most have 2, some have 3. Sounds like you have some very exotic ballasts over there.
UK mag ballasts have mean lives of over a century. AFAIK it has never dropped below this.
What I said was that their reliability does not compare to mag ballasts. This is true. Thus reliability is not a reason to replace the fitting.
lets keep it sensible now
I'm not sure why you're having difficulty accepting that one is more reliable than the other. They just dont compare when it comes to reliabilty. None of the above has anything to do with it.
We have precisely that situation with a whole range of consumer goods here. Many cheap end goods have appalling lifetimes, eg power tools that die after 10 hrs use. Sellers count on replacing a percentage, users buy them mostly in ignorance, and less often when they know but are in no position to take the tool with them. There are large quantities of angry customers, but far more that are willing to buy on price alone, so business continues.
Its probably best policy to establish the facts before being condescending.
To toss some numbers, suppose 100 units transported 25 miles each way in a truck that gets 8 MPG. (Really long trips would more likely involve a whole truckload of units.) One unit's share of the truck mileage is .6 mile, and at 8 MPG that's .075 gallon of gasoline. If I calculated right, that's roughly 2.6 kilowatt hours. A 25 watt power consumption only requires about 104 operating hours to make that up.
Somehow I suspect the factory's price for decent ones in quantities of
100,000's has to be less than the retail price of a cheap garbage grade dual-4-foot shoplight with a garbage grade magnetic ballast - and I have heard of about $10 for those. So, I don't think I'm badly out of the ballpark to pull out of a hat $8 for a 2-lamp 4-foot unit, FOB the factory's loading dock in truckload quantities. Just for the sake of argument, suppose 100% of that cost was for energy to obtain materials and to manufacture the unit - starting from dirt/rocks/air/water that is. Suppose 8 cents per kilowatt hour. That's
1,000 KWH, which a 25 watt savings will make up in 40,000 operating hours, which most 4-foot fixtures will accumulate in a decade or two.
Somehow I think that figure is high by at least an order of magnitude.
Weighing .005-.01 ton? How much diesel fuel to truck round-trip 20 tons of trash to a landfill 100 miles away - 40 gallons or less? .01-.02 gallon per unit - requiring maybe 15-30 operating hours for a 25 watt power consumption decrease to make up?
Usually not the case - sizes of fluoresceint lighting units are well-standardized. This is especially true for the ones to fit into the drop ceilings that most offices have nowadays, where a fixture replacement will not require repainting - especially not of acoustic tile!
Meanwhile, the share ceiling space associated with one luminaire requires how much paint? Something like half a dollar to a dollar's worth? Even if 100% of the cost of the paint is from energy consumption, that would be in the ballpark of half a dollar to a dollar's worth of electricity. At 8 cents per KWH, a power reduction of 25 watts accounts for half a dollar to a dollar in 250-500 operating hours. As for applying the paint in the unlikely event that is required - burn
No product can cost less than the cost of the energy used to produce that product and all it component parts, including all the energy needed to extract and transport the raw materials. This is basic economics.
The value of the energy saved is far greater than the cost of the new lamps, ballasts and luminaires. (If it were not, people would never make the switch.) Even if the user of the luminaire pays a higher rate for energy than the industrial users who built and transported the device, the cost savings would tend to rule out your assertion.
Internal connections, not external. That is one measure of mean time to failure.
How do you know this since fluorescent lamps have not been around for 100 years? Even if this is correct, and I guess it might be for a simple choke ballast, how many remain in ceilings for 100 years?
When Philips first showed the QL at Hannover in 1992 or perhaps 1993 they gave an estimated life of 60,000 hours (at that time) and said it was the "life of the building" since the space would be renovated before the lamp had operated for 60K hours. I'm not sure I agree with 60K hours life for a building space, but it is certainly not 100 years.
I agreed with this in my opening remarks.
So, are you comparing the reliability of electronic ballasts to cheap electric tools that fail in 10 hours? What is your point in this comparison?
mag ballasts normally have 2 internal connections, one at each end of the winding.
this is basic stuff. If for example 50% had died after 50 years, we'd know mean life was apx 50 years. If 10% died after 50 years we'd know mean life was nearer 500, etc. Lots of items are life rated at beyond the time theyve existed on this basis, standard industry practice.
irrelevant. Relevant is the failure rate in real life service times, which depends on mean life, or MTTF.
are you being serious here? The point is that lots of uk consumer goods are not reliable today. The point is that thus replacing an old fitting with a new one does not improve expected reliability. And that reliability is thus not a reason to replace the fitting.
This is only true for simple reactor ballasts. 2-lamp EM fluorescent lamp ballasts used in the US have multiple internal windings and two capacitors.
You must know this is only true for a linear mortality curve. Please take a look at a typical mortality curve and you will see that it is far from linear. The failure rate for times much earlier than mean life cannot predict the mean life point.
In UK, which is the area we're talking about, mag ballasts are always 2 wires, theyre just a series choke. 2 lamp shop fiting ballasts are also just a choke. Even 8' tubes use a series choke ballast.
yes of course, to all 3 points. I was simply pointing out one does not need to run fl lighting for 100yrs to see mttf for mag ballasts is over
2-lamp EM fluorescent lamp ballasts commonly used in offices here are just one ballast and two tubes in series, so that drops to just a single internal connection per tube ;-) (It also makes the ballast more than twice as efficient as a pair of separate ballasts driving separate tubes.)
This is partly what I was getting at in an earlier post where I said the economics just seem quite different between US/120V and EU/230V control gear systems.
I've never come across any simple series ballasts failing in UK fluorescent fittings (except in one case where water came through the ceiling). At this point, I think we can say their life is longer than they've been around.
We have also had some more complex EM control gear designs, but I've not come across enough to comment on their reliability as they're relatively rare.
Yes, and I think on reflection a century mttf is probably too pessimistic.
When they do fail, which is very uncommon, I wonder how many of those failures are secondary issues, eg ballast failure due to wiring shorting to case, which can place them directly across 240v ac. Or a glowstarter welded shorting, which puts most of 240 across the ballast.
I recently noticed that there are a few of these still in use where I work; two of them right outside my office. Most of them have had the ofiginal lampholders replaced, but it least one, in the sparks' workshop, still has the original ones, with bipin adaptors. In a little-used storeroom there are two that still have the original covers over the lampholders and clips. I'd like to acquire one of these when they are taken down. The whole building is being gutted and refurbished over the next few years, so they won't be there much longer. There was one leaning against the wall by the boiler house door recently, together with the box that its replacement came in. I looked at it, but the ballast was burned out. I had a word with the sparks, and he let me have the two large four-pin starters out of it.
Unless it's a very old thermal four-pin starter, you'll find that inside is just a regular glow starter across the locking pins, and the small pins are simply shorted together. It's most unlikely an original thermal starter would still be working unless it was in some situation where it wasn't used for 50 years.
I did notice "The Shop on the Bridge" in Reading had some bayonet cap fluorescent tubes on sale when I was last in there about 2 years ago. Knowing them, they might well be 1950's stock;-) Bayonet cap to bi-pin adaptors were very common 40 years ago when the bayonet cap tubes were phased out, but it's probably easier to buy a flying bi-pin socket nowadays and swap out the bayonet cap lampholder, if you want to run those lamps.
Of course, you could fit a modern ballast if you just want the fitting for 1950's styling.
I was using a thermal starter or 2 in the 80s, still working fine. The way they light tells you which they are, thermal or glow.
The ballasts are the same, so getting a dead ballast fitting doesnt stop it being fixed & used.
There is one gotcha with very old fl fittings, some have capacitors that contain pcbs, polysomething biphenols or someting vaguely like that. Supposed to be quite nasty stuff and prone to leaking, so treat old pfc caps with a bit of caution, especially if oily/greasy.
Where is this shop; I'd like to get hold of a bayonet tube, or two?
I'd like to get gold of one of the ones which still have the bayonet holders if possible, or failing that, one of the converted ones, and convert it back. I really want one with the original control gear. I did find one bipin adapter on the floor in one of the lift machine rooms, but I couldn't find another one. It has a small 'tab' on one side, which I assume is intended to make contact with the metlic stripe, on tubes that had it, MCFA I think was the designation. The lifts were replaced about 18 months ago; the original ones lasted about
50 years; I would be surprised if the new ones manage 20, Two of the old ones had beed modernised some years ago, but the third still had its dc drive and motor-generator set until it was replaced. The machine room has modern fluorescent fittings, probably installed at the time the lifts were replaced.
suggest you phone before travelling, to make sure they have one in the right size (supposing they still have any).
I can see the tab in a picture. The Thorn part number is GB1515.
Not sure, as you won't need MCFA tubes in these metal fittings with switchstart control gear. They were for Quickstart and Rapid start control gear where the tube was not near earthed metalwork. I don't think these starterless control gear types appeared until after BC fittings had gone, but I might be wrong.
By the way, the history of the bayonet cap fluorescent tubes is interesting. The first fluorescent tube installation in the UK was in one of the London Underground stations around 1937 IIRC. During WWII, there was a move to switch over to more fluorescent lighting, but the lampholders which came from the US were no longer available (I don't know if they were bi-pin at that point). Ever resourceful, they decided that if they were swapping out filament lamps, they could reuse the lampholders if the fluorescents used the same type, so fluorescents switched over to BC lampholders. The 4' tube (which was the original size used in the US at that point) was abandoned in the UK during WWII, and 5', 6' and 8' tubes produced because installations of these used fewer raw materials. The 4' tube didn't reappear in the UK for some time after the war (I guess mid
1950's, but I don't know for sure) and had bi-pin lampholders. The other tube sizes then changed to bi-pin too.
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