image 1
an old 700 watt microwave oven transformer
with its primary 240 volt windings. the secondary winding gaps are for another Do it yourself project.
the original high voltage 1kv secondary winding was cut with a hacksaw and pushed out, without disassembling the core.
leaving the low voltage side of the secondary intact. red wires.
image 2
here is an un-cut 700 watt primary 240 volt winding in its varnish collar from another old microwave oven transformer were the core was disassembled.
leaving the wire collar intact.
this is a lot of wire to unwind then poke through a new core to make a mains voltage isolation transformer.
I referenced this in reply #17. A re-wound MOT is absolutely the worst way for somebody to make a safety isolation transformer...
- The windings are probably CCA.
-
Never re-use old wire in a transformers - especially a mains winding, and you're uncoiling a varnished coil
- The chances damaging the wire insulation while threading the core are high.
- The secondary-core insulation is nowhere near good enough for a safety isolating transformer
- The average person doesn't have the necessary Hipot test equipment to ensure that the primary-secondary and secondary-core insulation and voltage withstand meet spec.
Don't do it, it's not safe for this application -
just don't.