On Wednesday, 24 April 2019 10:32:29 UTC+1, tim... wrote:
Currently the bulls we use are 2 times 7W CFLs

Assuming they're G23 base (PL type) then adapters can be had at about £1 each, so that 'ordinary' BC or ES E27 or E14 bulbs can be used, eg

https://www.amazon.co.uk/Starnearby-...dp/B07FM5F5KJ/

This may open up opportunities of much cheaper/lower wattage LED bulbs. ** the ballasts in the fittings would also have to be removed **

Perhaps if you put up a photo of the exterior/interior of the bulkheads, further suggestions may be made.

Owain