HF fluorescent lights

House power went down yesterday - looked at the CU and the RCD on the half which supplies house power and workshop lighting had tripped as well as the workshop lighting MCB. Reset, and all well except one fluorescent (2x58W tubes) unit in the workshop was out. Is it reasonable to assume that this can only have been caused by the HF ballast in the fluorescent unit failing? And if so is it OK just to buy a generic 2x58W replacement and wire it in, or is there more to it than that?

Sorry if this if a naive question - I suspect that the answers are yes, yes and no, but I've no previous experience of this type of lighting, so I'm not 100% on it.

Thanks for any advice, Rob.

I am awaiting with interest the experts' views on this as I have had rather similar problems: the ELCB trips when the workshop fluorescent lights are switched on, a problem which was apparently cured by changing the starter in one of the units.

As to the replacement of the dead unit. Yes, get another one of the same spec (or a spec that matches the tubes, if there is any doubt) and wire it in in the same way. It'll work. The switch mode power supplies in the HF ballasts can fail quite enthusiastically and draw enough current in a very short time to give circuit breakers a good short-circuit test. If an RCB/ELCB is tripping when a given device is turned on, it can be a sign that interference filters in the device are failing. It can also be because the breaker is failing and is tripping at a lower fault current than it should do.

Had this problem a couple of times at work and used up our entire stock of obsolete Square-D ELCB's looking for good ones, after testing with a current/tripping-time device that we'd bought for testing office/lab mains supplies at foreign power station construction sites!

Just buy a couple of LED tubes to replace the fluorescents - easy conversion and no more ballasts to worry about. I did this in my workshop and it's well worth doing.

Many years ago I was told not to use fluorescent lamps to illuminate rotating machinery as the stroboscopic effect can give the impression the machine is switched off

Unless my memory fails me!

That only applies to ordinary fluorescents working at 50Hz. The modern high frequency ballasts work in the KHz range and don't cause any stroboscopic effect.

John

Thanks John - how quickly knowledge becomes out of date!

Hi Andy,

No,your memory is not failing you,I was told the same.

As a Radio Amateur, I hate those HF FL Lamps with a vengeance! They generate so much EMI that the MW and SW frequencies are utterly decimated within many 10's of meters of the lamps. So the neighbors lamps have destroyed my Radio Amateur hobby! Did I mention I hate those lamps?

Joe

Even James Bond, and pretty well all other spies of fiction, knew to hold their confidential conversations under fluorescent lamps!

Yes indeed you can get very good stroboscopic effects, if your chuck is turning in multiple fifties of RPM. So what? If anyone thinks that the chuck isn't turning when the racket of the lathe is pretty loud, then they make a big mistake.

I NEVER assume that the chuck isn't turning if I can hear all that racket. Yes even though I have a clutch fitted to my lathe. Never assume the chuck is stationary. In all the time I have had a lathe illuminated with fluorescent lighting, I have never seen a stationary strobe effect. Sure the chuck often looks as though it is going slow, either backwards or forwards, but I have never managed to get the picture in complete stationary sync .I think it is one of those urban myths.

Right. I am waiting for the explosions to fall around me!

Andrew.

I did once get this "static chuck" phenomenon in a very noisy training room when I was doing evening classes. Got - quite rightly - admonished by the instructor for not first ensuring the clutch of the Harrison toolroom lathe was disengaged, and for not switching on the spotlamp before pressing the start button.The lathe was new, and quiet.

I recently did an EMC review of my workshop and was surprised to find my tubes (2 x conventional plus 1 HF) were "clean", unlike the lathe VFD. Of course my test was quick and the antenna crude, so I might have missed something. Even so, like everything else, presumably not all lamps are made to the same standard.

Man made electronic smog around my house makes amateur radio difficult at all times. It's amazing how much crud disappears when I get the chance to listen on battery power during a power cut. I don't know whether to be pleased or annoyed that power cuts are so rare here!

Dave

Dave, I couldn't agree more! All the really cheap AC-DC converters in every house hold appliances these days, printers, fax-machines, modems, mains driven LED lighting, FL lighting, etc - most of these are open frame switchers, in plastic housings and so it goes on! Like you, when there is a power failure I rush to the HF radio..My desk in the shack has a 2 tube HF FL light above the desk, which I turn off when trying to listen to HF and use a plain incandescent desk lamp instead! I suppose we are suppose to to Hamming via internet these days - whats with this HF nonsense!

Joe

Thanks Mark - sounds like my guess that HF ballast must be the culprit seems reasonable.

Thanks also to others who replied.

I have never had any problem with strobing - the guy who wired up my dungeon knew it was to be a workshop, and recommended HF for this very reason. They run at tens of kHz I think.

I've considered replacing the fluorescent lighting with LED tubes (I think there is a discussion of these elswhere on this site), but as I have 16 x 5200 lumen fluorescents in total, it would be expensive up-front. I'm not sure about the benefits in terms of running costs either. There seems to be law of diminishing returns in terms of lumens per watt with LEDS - just had a look at simplyled.co.uk and the replacements they offer for 58W 5ft T8 tubes are rated 24W / 2550 lumens. Only £11.51 / tube mind, cheaper than when I last looked around. Maybe all lumens are not created equal though - I've replaced most of the GLS bulbs in the house with LED versions, and subjectively they seem brighter than their lumen rating compared with incandescents would suggest. I imagine perception of brightness varies between individuals though.

Robin.

This thread has prompted me to replace my workshop flourescents with LED. There seems to be a humungous choice, do I go for tubes, or that continuous strip? What colour temp. Anyone out there who knows?

I've already replaced a lot of tungsten and CFL bulbs in the house with LED. In one fitting which has three BNC candle bulbs (ToolStation code18765) I get a lot of flickering. Is this because there are three bulbs close together, or just rubbish bulbs. I don't have a dimmer, and I tried replacing the switch to no avail.

Edited By duncan webster on 12/07/2017 21:05:56

Robin - I thought the same as you regarding lumen ratings until it was explained to me by a US pal. A standard fluorescent tube radiates light around its entire circumference and much of the light which goes above the horizontal is lost unless you are using some kind of reflector above the tubes. An LED tube only radiates light below the horizontal, so the perceived brightness is a bit higher. I had standard Tri-phosphor daylight (6000k) tubes rated at 5200lm in my shop and am replacing them with 24W Cool White tubes that are rated at 3230lm - the LED ones definitely make the shop brighter, though that could just be my perception.

Duncan - I used 4000k Cool White LED tubes at the suggestion of a friend and find them just about right. Don't buy self-adhesive strips, as they have no built in reflector and they've always seemed dimmer to me anyway. As for your flickering three - suggest you try some different bulbs first. Dimmers specifically rated for LED use are readily available and those which I've tried work well.