High Frequency lighting problem.

Hello chaps,

I fitted two twin 1200mm high frequency fluorescent fittings in my workshop and I was seeing problems where one or both fittings would intermittently cut out then come on again either a few seconds or minutes later, or not come on at all when first switched on.

They are connected in a standard lighting circuit via a single pole switch and 6amp MCB. One fitting is looped off the other so they both come on together.

I found that disconnecting one fitting allows the other to work without cutting out, but I would like both to give adequate lighting and for obvious safety reasons.

Is this a known issue with HF fluorescent lights when looping from one to another? Can anything be done to rectify it?

Btw I was an electrician for 10 years working to 15th edition before HF lights were commonplace so I've not fitted any before these.

Thanks and Happy New Year to all.
Ed.

Edited By Ed Duffner on 29/12/2012 13:01:31

Funny you should bring this up as i fitted 2 4f twin lights too that are hf , I had to take one of the tubes out to get the second light to work other wise it just flickered then both tubes would go off. Not sure how to sort it out tbh.

Hi Ed, even the old type of fluorescent fittings don't always behave. I have a 6ft 125W one in my garage which is run off an isolating transformer, because its knocks out my RCD otherwise, no ovious reason why.

You could join this forum, and ask on there **LINK**

Regards Nick.

Thanks for the link Nick I haven't come across that forum before.

Re: your 6ft fitting. Some of the old ballast units used to rust in garages and outside buildings causing slight leakage to earth. Old irons, kettles and fridges can cause RCD's to trip as well.

Nick,

Not unusual, capacitor across the line can have rather high leakage to earth and hence RCD does not like it.

Hi All,

I would try wiring the units separately to different parts of the supply system, put a plug on one and connect via an extension lead to a 13a socket, there may be a beat frequency between the units. If this works then two runs of cable and may be a double switch will cure it ! Used to work in this field, but before digital hf units were thought of.

Good Luck Noel

Hi Ed,
You could try inserting a mains filter in the cable run between the lights. This should reduce the effect of any noise from one fitting reaching the other. Most devices using switched mode power supplies have some filtering built into them to prevent them inducing too much electrical noise back into the mains.

Les.

Thankyou Noel and Les for the suggestions, will definitely give them a try. I have a plug in filter which I can also check out via 13A plug.

Happy new year.

Ed.

Hi Ed,

Hope you see the light in 2013!

Happy New Year!

Neil

Hi Ed, this fitting was removed from the workshop where I used to work a few years ago. It was working OK when it was removed, the workshop lighting was upgraded to stronger bulb type discharge lamps for better lighting as it was a rather big shop, but it was a dry well heated shop. I checked it out completly for any faults and earth leakage with a megger on the ballast and a capacitance and an ohm meter on the capacitor and no significant leakage to earth was found. Other smaller fittings work fine.

Regards Nick.

Happy New Year to all.

Edited By Nicholas Farr on 31/12/2012 23:16:35

Hi Ed, i had similar problem, i changed the starters & fitted good quality ones,about year later got same thing, now wired them to seperate switches only have 3 lights but this has cured the problem, dont know why??? friend mine had problems so he fitted LED tubes, no more problems&his workshop is so much brighter.

Garry