I have brought some old Coughtrie type lights from ebay. I was going to recondition them and fit them in my house. I am struggling to find out the thread sized used on them.
The inlet/outlet is close to a Modern 20mm conduit thread, but the 20mm is a bit small. Do any old timers know what the standard conduit sizes would have been?
Internally I have got to replace the lamp holders and earthing straps. Likewise a modern M4 conduit screw is loose in the hole. Id guess it would be about M5, but obviously its going to be some kind of imperial thread.
I have a rusty conduit screw and a (plastic!) plug that I can measure, but I always find sizing imperial fittings confusing. For example 3/4 BSP as used in plumbing is 1" diameter!!!
The inlet/outlet is close to a Modern 20mm conduit thread, but the 20mm is a bit small. Do any old timers know what the standard conduit sizes would have been?
Internally I have got to replace the lamp holders and earthing straps. Likewise a modern M4 conduit screw is loose in the hole. Id guess it would be about M5, but obviously its going to be some kind of imperial thread.
I have a rusty conduit screw and a (plastic!) plug that I can measure, but I always find sizing imperial fittings confusing. For example 3/4 BSP as used in plumbing is 1" diameter!!!