Are fledgeling swallows, well-feathered and feeding, likely to be disturbed to the point of harm by work undertaken near them viz. lights, drilling, dust while fitting an electrical panel in three days time?
That is a tricky one to answer. Have they fully fledged i.e. flying from the nest, attempting to hawk flies for themselves and possibly just using the nest to rest between flight training and strengthening? I have found swallows to be very tolerant of all sorts depending on where they have nested - I used to stable my horse in a barn system and it was a joy to have the youngsters zipping in and out of the barn, using the the tops of the stalls as launch pads and on the odd occasion even on the horse. 3 days will be a huge difference in the birds development as well.
this is a link to the law www.rspb.org.uk/.../
Cin J