Inside a 10kVA pole pig
This is an old 10kW pole transformer I scored from uni. It had shorted windings and when I opened it, I found out why. The transformer had nearly an inch of water in the bottom and was full of rust. Anyway, I pulled the core out to use it as a ballast, and thought I would show you all what is inside for those who are interested!
The HV windings look like about #24, and the outer two layers are cotton insulated - probably to help protect the transformer from HV spikes caused by lightning, etc. These are wound over the LV windings - a bifilar winding of about #12 wire which allows the use of 250 or 500v input (or actually output when used for its intended purpose). The core is of the "c" variety, and can be seen on my homemade ballasts page.