Theres the electricity commission website which can give a list of wiremen. PW1 is single phase, PW3 is 3 phase.
https://ecos.st.gov.my/senarai-orang-kompet...aftar-elektrik-

And you use google maps and cross reference with the commission website.

The water commission website search is better because it had the address of the certified plumbers so its easier to narrow down the search. You could also ask a nearby electrical or hardware store for recommendations since they deal with contractors.