To directly answer your question, both "electric" and "electrical" are correct, they are both adjectives with the same meaning.
Anyway, proper name= a proper noun that is not a title (Doctor is a proper noun that is not a name, it is a title) If say 'I am going to the grocery store', "grocery store" is a general name/noun. There are many proper names of grocery stores like Tesco's in Britain and Aldi's here in America. "Tesco's" is a proper name, that is why it is capitalised. If you know what grocery store you are going to, you say 'I'm going to Tesco's'. It is also a person's name I think, so to give another example here we have an electronics store called "Best Buy". Because you see if we called every grocery store "Grocery Store" we wouldn't know which one we mean.There was a restaurant called the Rainbow Room, that is a proper name, the Ritz Hotel is a proper name. I am going to the hotel. (general) I am going to the Ritz Hotel (proper), Abbasi Hotel or Azadi Tower in Tehran. I can't tell Iran ' You can't call it Freedom Tower because a tower can't be free', Iran can name it's buildings whatever it wants, right?
The shop in your picture has a big bright sign in front that says "Electric Shop" so that is the proper name of the shop, and not just a general name.
As someone said there aren't many shops that sell only electric supplies, and usually their general name catagory includes the word "supplies", but those that do exist sell the kind of things for building houses or work that an electrician would do,or in large quantities. Shops that sell electric appliences like refrigerators, cookers, washing machines and dryers etc. are sometimes called appliance shops and those are also disapearing. Often they would have another name with "electric" like "Smith's Electrics" or the like.
Things like irons, toasters and coffee makers are found in a section of department stores, there is not usually a separate shop that sells just those items.