Im am quite stunned as to what might be wrong. electronics beginner

I bought today some copper wire, 20SWG /0.9MM from maplin (UK), for a project I am working on.

There is no power going through the wire. I got positive and negative of 9V battery going to breadboard, then two pieces of copper wire one in + one in -. No voltage on the multimeter. Exact same setup with jumper wires work.. Copper wires are inserted fully into the breadboard... What am I missing ?

p.s Label says: 250g EN COPPER 20 SWG 0.9MM


3 Answers 3


My guess is the "EN" of the code means "Enamelled" - I.e., it's coated with enamel.

That kind of wire is meant for winding transformers, inductors, and electromagnets etc. The enamel coating insulates the wire and stops a coil turning into a single lump of copper.

You need to remove the enamel from the ends of the wire, either with a small craft knife, or burn it away using a hot soldering iron and solder.

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    \$\begingroup\$ +1 The enamel is often (not always) clear or copper-coloured so it's not easy to tell that the wire is actually insulated. \$\endgroup\$ Commented Feb 10, 2015 at 20:59
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    \$\begingroup\$ A match or a lighter works pretty well too \$\endgroup\$ Commented Feb 10, 2015 at 21:00
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    \$\begingroup\$ If you put the wire into the lower, blue part of the flame of a lighter, you should not have any trouble with carbon. Even if you get some carbon, it can easily be removed. To burn the enamel with a solder iron, the temperature must be quite high. My favor is a desolder pump as it usually is hotter than the solder iron and putting the wire into the nozzle is even more effective. However, I guess @Giannis does not have a desolder pump... \$\endgroup\$
    – sweber
    Commented Feb 10, 2015 at 21:40
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    \$\begingroup\$ EN for Enamelled is it. 400-grit emery paper works well. \$\endgroup\$
    – user16324
    Commented Feb 10, 2015 at 22:20
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    \$\begingroup\$ Thanks for the comments. This is quite annoying as I also bought another wire which I needed to be enamelled, and that one said enamelled on it (same place) so I didnt bother asking what EN meant..Lighter seems to work.. \$\endgroup\$
    – Giannis
    Commented Feb 11, 2015 at 10:34

I used to remove enamel off copper wire (small: #34 guage) in a production environment by dipping in a Kester solder pot. The molten solder burned off enamel and tinned the wire for transformer leads very nicely.

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    \$\begingroup\$ Doesn't this ruin the solder? \$\endgroup\$
    – sharptooth
    Commented Feb 11, 2015 at 14:20
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    \$\begingroup\$ You'd have to tin a huge amount of wire for the minuscule amount of enamel to even make the slightest difference to the considerably larger amount of solder in the pot. \$\endgroup\$
    – Majenko
    Commented Feb 11, 2015 at 15:43

As a fun fact, my grandfather used to remove the insulation of these wires using a very special technique. He'd get a a pill of aspirin or penicillin (don't remember which) and glue it to a piece of wood. He would then take his soldering iron and while heating the pill, the wire would be drawn through the molten medicament.

This horrendous hot chemical compound was apparently aggressive enough to disintegrate the coating entirely. The only downside was that it produced an enormous reek. The intensity of this smell isn't comparable to anything I've ever sensed.

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    \$\begingroup\$ Definitely aspirin, aka acetylsalicylic acid. I've seen it used instead of flux for tinning wires by a russian DIYer. It wasn't as good as my chunk of violin rosin. \$\endgroup\$ Commented Feb 19, 2015 at 0:52

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