I don't think circuit is a very useful tag, as I can't think of any time you'd use it as the only tag on a post. I also don't think many folks would use it to find questions they might be interested in.
The tag should probably be removed.
I think when it started, the tag was for questions that had to do with the electrical system beyond the service drop. Transformers, types of systems, etc. However, it's likely not used properly, and can probably be killed.
The tag can be removed from any questions that are not asking about the distribution of electricity.
I merged them because “home-wiring” seemed redundant (this site is all about homes) and there was no clear difference between questions tagged “home-wiring” and questions tagged “electrical”.
They are the only tags I merged. Perhaps I should have discussed it on meta first. I didn't because I didn't think it would be controversial, just a janitorial task.
I'm worried that this would create a lot of management overhead, and still not solve the specific problem. I see two solutions to the "no country provided" issue:
Everyone can answer in reference to countries they know and identify that country in their answer. This way, anyone searching for the question in the future can see their local solution among the ...
I created a new tag, refinishing (because we have the other tags basement-refinishing and hardwood-refinishing this seemed like the logical choice for a name), and merged the typo tag refinsh into it, without creating a synonym.
End result: all the questions that had the bad tag on them now have the new tag instead.
I would not like to see the tag blacklisted, since as Chrisf says, there are situations where generic applies.
I wouldn't oppose having regional based tags, however. Possibly some core region tags like US, UK, etc. and then synonyms for them like "electrical-uk", "electrical-us", "plumbing-us", "plumbing-uk", which would show up when they typed "elec..." ...
wire is only a good tag on questions that ask specifically about wire. For example: "Is there a difference between stranded and solid wire?", "What material is the insulation of THHN wire?", etc.
If questions are tagged with the wire tag, but are not discussing wire. Then that tag should be removed from the post.
I think you could try to retag some if its absolutely clear what they mean, but I would wager that most of them are not specific enough.
Adding a more specific tag in to help future searchers is good, but I agree that the generic [gas] tag is required.
I would point out that in some countries "gas" is the only term people would use to describe what others would call natural gas and or propane because gas is not a shorthand for gasoline. Some people would never tag propane or natural gas as its not a term they would ever be familiar with.
I think one of the problems with this is that it's not actually getting to the root reason for why it might make sense to regonalize the tags.
@NiallC referred me from a related answer I gave, where the question was originally about clarifying 120V/60hz vs 230V/50hz etc without being overly technical for users that may not understand voltage/frequency (...
We can certainly get a tag blacklisted.
We would have to go through all of the electrical questions - all 689 of them retagging as appropriate before the tag could be blacklisted.
Though I'm not sure of the benefit of this. There are questions - this recent one for example:
How do I install electrical through "new work" stucco?
that are ...