I have heard of people stating that it is not a good practice to tape a wirenut, that they are not rated for such. Is this true and what would be the reason, poss withhold heat? i dontt know but maybe someone out there does.
I had a journeyman hated both tape and wire nut drivers. His rational was that half the time you will loosen the off the nut while putting on the tape. Then there’s the goo that seeps out over time or the next guy goes to pull off the tape and the wire nut pops off allowing the wires to possibly short out. Where we did use it it had to be done to a certain specification. I think he said it was UL OR CSA I cant remember. But you start from below the nut working your way one full width past the top of the nut fold it over and work your way back down leaving the end where you started from. As for wire nut drivers I’ve seen it happen where one of the solid wires would actually go through the top of the wire nut leaving a hazard for next guy. I think taping wire nuts is a throw back to to the older style of wire nut that had the set screw to hold the wires and a twist on cap.
Wouldn't call it a good or bad practice, just un-nessesary. And once it's in the box, you're done, or so you think. Eventually someone will demo your work for some re-model, and think, "Oh, it's those 3M Red/Yellow's again, what were they thinking with that little skirt anyway?" Someone will get to look at your work as an archelogical site. Much the way some of us look at soldered and taped splices...
I'm not old enough to have done it, but have worked for older guys who have. Back in the Knob and Tube, and Black Steel RMC splices were cleaned, bound, twisted or lashed. Then soldered, cleaned again, then taped with rubber, then friction tape. I was told the idea was to seal the joint so it wouldn't oxidize. (I was taught to do kearny bolts the same way, minus the solder. And simularly for electronics soldering, minus the tape.) Anyway, a lot of those splices have lasted over a hundred years, so I don't think there's a heat trap issue.
Anyway, I think the taping of wire nuts is an un-nessesary throw back to those days of soldered joints. I have also seen some of the early wire nuts taped as if they were soldered, like they didn't trust them. (I know someone is going to disagree with me on this.) But maybe some of the more senior of us can have a hand on this. (I'm sure Joe T. could shed some light on it, as I have seen some posts with him and others reminising about the "Solder Pot Days")
Personally, I think we should move on to set-screw pressure terminal strips like they use in Europe. Seen too many wire nuts fail...
Mark Heller "Well - I oughta....." -Jackie Gleason
I tape wirenuts, which I attribute to my begginings as a machine electrician. It was a requirement where I worked. The accepted feeling was that without tape, vibration would loosen the nut.
I recommend tape where there's vibration (dishwasher, furnace, vent fans, ceiling fans, etc.) and also for emergrency circuits, where a loosened connection would be more than an inconvenience. In the end I tape them all rather than thinking about it.
However, I use a method that makes it easier to untape the wirenut, which I think is the real issue about taping.
I run across, on a regular basis, wirenuts that are used out of their application range.
Very often they are taped, as if this does something to increase the capacity. (how about 7-#12 in a red, or 2#6 & 3#8 in a big blue one). The installer might as well have just twisted them together and taped them. It's usually an easy call when troubleshooting, and quite often the source of a failure.
As for taping them within their range...Why??
Outdoors, I should think that the taping would increase the likelihood of moisture retention rather than keep moisture out. (Guys have done that, too, mostly too lazy to go to the job box and get the Scotchkote).
Howdy, Working in an industrial area, (first chemicals, now coal-fired generation) I have taped wirenuts for cleanliness issues. Both areas had a great deal of dust that seemed to get everywhere. I have removed my own tape years later and the connection was still clean. You couldn't tell what color the wires were until the tape was removed.
Sadly in industrial situations there aren't too many applications that don't get "revisited" for equipment removal and such. (We have always reserved wire nuts for lower voltage and for frequently accessed devices.) Everything else gets a more permanent connection (terminal bolts).
I've taped the wirenuts on pigtails in switch boxes that were likely to get played around in (later HO switch replacement and such. The same reason I tape switches and receptacles. As far as doing 100% of them, I don't.