How to get Polish Electrician's license?

What is required to be able to use a trade license from another country? I assume an equivalence test of some sort?

I haven't heard about any equivalent test - I doubt it exists in Poland. I'm not even sure if an electrician has to have any special permit to do the job (in official constructions it probably has, but in private or small business maybe not).

sep.com.pl/index_en.html

I guess if you got in touch with them, they would be able to point you in the right direction :-)