Why is it required in some countries to sleeve uninsulated earth wire in junction boxes, but not required and not practiced in other countries?

Question

I don't know if the better question should be "why does, for example UK, require earth wires to be covered in a yellow sleeve in junction boxes", or should it be, "why does, for example USA, NOT require it and why don't electricians do it as a best practice?" ... but it seems like a fairly fundamental idea that is either an excellent and safe one, or an unnecessary one, and I would expect at some point in history there would be consistency. What's behind this?

Answer 1

On one hand it improves safety very marginally... on the other hand it escalates time and cost. Simple as that. In marginal-benefit cases like this, every country makes that call in their own way.

The builders have a very strong lobby within NFPA, which is why improvements are highly valued which let the builder work faster, like backstabs, wire nuts or plug-on-neutral breakers. A proposal to amend NEC to require the sleeves would need to be supported by a body of evidence documenting fires which the bare grounds have started. Since NFPA is, after all, the National Fire Protection Association* and gets fire reports from most fire chiefs, they have that data.

Note also that the UK line-ground voltage is twice North American voltage, since we actually do the center-grounding that the UK only does on construction sites. As such, open-air arcing between a live terminal and a nearby bare ground may be more of a risk in the 5-continent system.

* Weirdly you'd expect them to be the National Fire Prevention Association. The National Fire Protection Association should be teaching artillery crews how to deal with counter-battery fires, and the fine art of "shoot and scoot".

Answer 2

Seems common sense to me to sleeve any bare wires jumbled about in a box along with live conductors and cables. Especially since you can't be 100% sure what's going on when you push the covers back.

I regularly see electrical boxes stuffed to the brim with 'added' cables after 'improvements' and you can barely force the cover back on. This blind pushing could in theory push a bare cable somewhere it's not supposed to be.

I often see bare earth wires here in Norway, but as I'm British, they always get a bit of sleeving from me before the cover goes back on. I also often see those wire nuts which I always find amazing, like something temporary a kid would do... WAGO is the only way for me I'm afraid.