On 28/04/2019 11:08, Mike Clarke wrote:
On 27/04/2019 20:45, Alan wrote:

I wouldnt bother, just buy a LED tube and modify the internal wiring as
necessary. They are really cheap now.

That's what I'd originally considered but a 6ft LED only gives 2600
lumens compared to 6200 for a fluo.

That's a large difference and staying with fluorescent seems sensible.
Although a quick search returns 6ft LEDs with over 3000 lumens and a
more in-depth search may find better still.

Also remember that LEDs don't have to produce as many lumens as
fluorescents for the same effect - because LEDs usually produce over
180°, while fluorescents produce over 360° and only a proportion of the
upwards lighting gets reflected back from the fitting and the ceiling,
with some being absorbed.

I must admit that I am interested in replacing some 4ft flurescents with
LEDs, but because of these differences, I don't know what ratio of
lumens output will give the same level of lighting.

But I'm having second thoughts on changing the ballast anyway. A new
Thorn 6ft PopPack batten with HF ballast and tube costs a couple of quid
less than an electronic ballast and tube - and I need a new tube anyway.

Probably the best option.

SteveW