I need a wire nut large enough so that I can bundle seven 14 gauge neutral wires together. I am trying to splice it so I can connect it to my new smart wifi leviton light switch. I don't know which wire nut size to buy. The boxes say for example: minimum 2#14 gauge - maximum 2#10 gauge. My question is, can you tell me which wing nut or brand or size to buy so I can group 7 neutral wires together? None of the sizing chart on the box says the exact words of "ok to bundle seven #14 gauge wires together. Which one should I use?
You would not bundle seven under one wire nut. I expect someone will amplify my answer with direct code call out. Basically, no more than 4... almost EVER, under any wire nut, and you must use the nut sized for the largest collective wire awg you are using. (not just buy a larger wire nut to stuff more inside of it).
Further, do not exceed the current rating of the breaker and in general having a situation like this begs the question whether it is smart to run another circuit to break up the load and the distribution path. Either way, exceeding 4 is typically not advisable and a fire hazard.
What you would do, is use up to 3 neutrals and a ~6" white jumper, and then 2 more neutrals, and another ~6" jumper, followed by one more wire-nut with 2 neutral and the end of the last jumper. Here you are distributing the wires as even and safely as possible provided it fits safely in the box and the circuit is not overloaded.
The box for the nuts you intend to buy certainly should list a limit on them. If you tell us the gauge (all are 14awg)? And the brands you are looking at it would be easy to lookup their recommended limits. E.g.: https://www.idealind.com/content/pdfs/catalogs/wire-connector-catalog.pdf
In the description These list 7#14's however the box only says 4-#14's on the outside.
Instead of trying to put them all under one wire nut, make a short jumper and put 3 under one wire nut and 4 under the other.
Make sure you strip back enough wire to make the joint work. Test each wire by pulling on it after you make up the joint.
Edit: You asked about push-in type connectors in a separate question and I didn't think of those when you asked this question. A push-in connector may be your best option in this case. As long as they are Listed by a testing laboratory such as UL. Ideal and Wago make 8 port connectors that are UL listed.
Every wire-nut manufacturer lists their wire nuts for certain combinations of wires. And UL tests the wirenut for all those combinations.
They put a brief summation of the ranges on the box and literature. But if you dig deeper you can find the master sheet listing literally every tested combo.
You might, but I doubt, find one listed for seven #14s. Far more likely to find them listed for 4 or up to 6. So do as noybman discusses with the pigtails, every extra pigtail of course adds 2 wires the nuts must share. So you can do it as 4/5 or 4/4/3.
You will also find other binding devices that handle up to 8, including the vile "stab" type splices, or the much better clampdown splices.