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Redders  
#1 Posted : 09 May 2017 08:52:29(UTC)
Rank: Forum user
Redders

A new fluorescent light has been fitted adjacent to a lathe in our workshop and one of the engineers asked about stroboscopic effects. There was an old thread on this and HSE guidance refers to this being rare with modern lighting. Is this still an issue nowadays?

A Kurdziel  
#2 Posted : 09 May 2017 10:00:55(UTC)
Rank: Super forum user
A Kurdziel

When you order new lighting etc these are the questions you should be asking!

As you have had the lighting fitted, then why not try it and see!

Modern fittings are better at this than older fitting but it depends on the speed at which you lathe etc.  is turning. See https://en.wikipedia.org/wiki/Fluorescent_lamp#Flicker_problems for a more detailed explanation.

Redders  
#3 Posted : 09 May 2017 20:52:37(UTC)
Rank: Forum user
Redders

Thanks - good response! I've asked the engineers to run the lathe and let me know if they experience any stroboscopic effects. We'll worry about it if they do.

Cheers

paul.skyrme  
#4 Posted : 10 May 2017 06:57:52(UTC)
Rank: Super forum user
paul.skyrme

The issue is with swtich start fluorescent lights, the ones with the little round "starter" in the side.  Often they don't start instantly and may flicker on start.

They can flicker @ 50Hz, thus 3000 cycles per minute.

Now 3000 rpm is the synchronous speed for a 2 pole motor, however, with slip, which is needed the true speed will be nearer 2700-2960 rpm, depending on design & load, it will never reach synchronous speed, even off load.

It is very doubtful that your lathe will allow access to the running motor.

Thus the hazard is from the chuck/workpiece.

Check the speeds if they are fixed, and see how close you are to 50Hz/3000 rpm, and, even multiples & sub-multiples thereof.

If you have an HF light, which gives almost instantansous light, then the flicker frequency depends on the control gear, and is likely to be well away from any turning speed on a conventional metal cutting centre lathe.

Mind, if this is a new circuit, the electrical designer has a duty to have mitigated this, and if it is a new circuit, then you will have an EIC in accordance with BS7671 which will state that the design has been done in accordance with the requirements, so you have nothing to worry about, it's all been dealt with.

If it's not a new circuit, the people working on it should have been aware, and still mitigated any chance of this without you having to ask, else they are not competent.

HTH.

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