Proper technique to adding a wire to existing pigtail

Question

This seems like a pretty straight forward question and hoping not a poor question but here we go.
If you have a pigtail for three wires (say # 14 AWG if that makes a difference) together in a wire nut but you want to add another wire to the mix. Is the proper method to undo the wire nut and untwist them and try to straighten out all three as best as possible? (In IT there was a tool to straighten ethernet wire but haven’t seen such a thing for Romex). Then line up all four wires (new one included) so they're parallel and retwist again from scratch and wire nut it with a fresh new wire nut? Seems like a commonsense answer but with all things in life you can never be too sure and curious if professional electricians had a technique of their own to share.

Harper - Reinstate Monica · Accepted Answer

It doesn't really matter how the wires were before.  The wire nut is gonna reshape the wires when you crank down on it!
The #1 blunder with wire nuts is being too much of a softie and being afraid to use the nut to reshape the wires.  You have to!  If you don't, the wires won't mesh firmly, you won't have good contact, and the connection will overheat, arc and start a fire.
A properly done nut should pass a "pull test" -- hold the nut and yank on each wire, one at a time.
If a nut fails a "pull test" then it's either a problem with technique, not tightening enough, not lining up the wires evenly, or using the wrong nut - i.e. using a wire nut right near the extremes on its bell curve.  Go up or down a size, please!
If somebody's going for "tape" to keep wirenuts from falling apart, they usually think they are doing a great job securing it, actually they have a bad connection to begin with that is likely to melt and burn up from arcing.  The job isn't to physically hold the wires together, it's to electrically do that.

DMoore · Answer

Harper has probably seen everything and has more experience but I come from a flipper who does things right point of view - try to speak in common terms.
The #1 issue I see is homeowners (or poor electricians) trying to wrap their connections then throw a nut on it.    They are all flimsy and it drives me nuts because it is a bit of work to straighten out the connections and start over.
Given that you have a good wire nut that is properly sized (not overly big or little).

you match up your 2-4 wires and try to give them 3 inches or so of being "straight and even"
you squeeze them into nut, straight and even.
you twist the hell out of the nut while applying a little bit of force into the nut so each wire sticks to the end.
stop when the wires outside the nut start to become overtwisted - or you run out of physical length
you can check a good pigtail by unscrewing the nut 3-4 times and your nut comes of but your wires are locked stranded together.

If unscrewing nut unscrews your strand then you are probably getting to the limit on what that nut can handle.   If you unscrew nut and wires are still loose there is a good chance the nut was too big or you did not have your wires straight and even.   If a nut is for 2-6 #14 and you are pigtailing 2 #14, chances are the nut will not do a good job binding the wires.
OR the OMG maybe they will modularize electrical to make electricians obsolete pathway :)
Buy the appropriate wire connectors and skip the nut all together.  (these are not my recommendations, just pictures for reference.   Please read specs for any that you buy, and some do not work with stranded.

The next picture is an aluminum pigtail example.   I have used this model.  I have actually used this enough to where I should buy stock (these are EXPENSIVE).   But they are very homeowner, DIY friendly.   Also pigtailing existing aluminum is hard when you don't have a lot of slack in the line.   Often times the ends are burnt a bit so risking twisting is possible breaking off 1.5" of a line that is already short.

Proper technique to adding a wire to existing pigtail

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