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# Breakdown voltage of enamelled copper wire?

#### cupoftea

Hi,
Do you believe this table can be right?
It says that even grade 1 enamelled copper wire of diameter 0.2mm is good up to 1800v.....can you seriously imagine a criss-cross of 0.2mm wires....each 1800v apart, and its not going to spark?

from https://e-magnetica.pl/enamelled_wire

"Typical electric strength of the enamel is around 170-220 V/μm, which is why a relatively thin layer of enamel can withstand significant voltage. For example, the 0.375 mm wire with the cracked enamel shown above has a voltage breakdown of 4.35 kV despite the enamel thickness being only 0.0275 mm."

remember there is enamel of both wires, so the insulation thickness at your crossover is about twice as thick.
its not the diameter of the wire that matters, its the insulation thickness.

i would also suggest that magnet wire does not generally have 1800 V from turn to turn.
if the coil has 10 turns and 1000 V across it, then there's only 100 V from turn to turn, etc

i spent a lot of time doing reliability analysis. i suggest you check what the derating
of the various enamels used for magnet wire

i think the table is correct, mostly on the assumption that its been out there for a while and errors have been corrected, and there's so much data, it was calculated.

if I'm reading the table correctly:
0.2 mm wire has a (grade 1) breakdown, as you said, of 1800 V according to IEC 60317
0.2 mm wire has a (class 0) breakdown of 3800 V according to JIS C3202
0.2 mm (about 32 AWG) wire has a (grade 1) breakdown, according to NEMA MW1000C (inch) of 1020 V

different standards for different views on safety.

cupoftea

### cupoftea

Points: 2
until the wire is knicked or scratched in the winding ( or other ) process

real care must be taken in deciding what volts per turn can be tolerated, between turns and between layers

esp if the wdg process allows a wire to be pulled down the side of a bobbin or other place it shouldn't go

cupoftea

Points: 2