Greg,
Splicing in the enclosure is permitted under various circumstances and various reasons. However splicing two neutrals together and pigtailing them to the neutral connection point is not specifically permitted and is quite frankly dangerous and sloppy work. So far we have not been provided with any specific NEC references allowing the condition in your picture but there are plenty of references disallowing it.
https://www.nachi.org/forum/attachment.php?attachmentid=204005&stc=1&d=1539539566
First we will look at a properly wired circuit with each neutral landing on its own lug on the terminal bar (see diagram above). These are all simplistic diagrams only for illustrative purposes. I’ve left out the over current protection devices (OCPD, breakers but just expect they are there). In this case if you lose the connection to the neutral tie point in the enclosure, and as long as it is not shorting somewhere else, all you have is an open and dead circuit.
https://www.nachi.org/forum/attachment.php?attachmentid=204006&stc=1&d=1539539644
Now we will look at the condition when two neutral, ungrounded conductors are wirenutted together and pigtailed to the neutral terminal bar. First we have absolutely no idea what those branch circuits are truly for and how they have been installed/wired in the home. You should always err on the side of caution and expect they are just two common branch circuits for lighting, outlets, etc.
- In your picture the first issue was brought up by Roy about the potential for overload on the pigtail. We have no idea what the branch circuits contain as far as load/current draw. The pigtail does appear to be the same gauge wire as both of those branch circuits.
- The second issue can occur if the pigtail connection was to fail for whatever reason but the supply side connections remain. If you close only one of the two switches nothing is going to happen. Close both switches and you created a path back to the supply side and the same buss it originated from instead of the proper return path.
https://www.nachi.org/forum/attachment.php?attachmentid=204007&stc=1&d=1539539706
Now we look at the conditions with each branch on a different buss/phase. Loose the pigtail connection and you now have a 240 VAC branch circuit instead of a proper 120 VAC branch circuit. You will most likely be, at the least, dropping/damaging anything connected to those branch circuits until either the OCPD in the panel trips or something burns out (lights, outlet, TV, or whatever is connected to it) to open the path. Hopefully no fire results from it.
There is nothing in the NEC specifically that allows this condition but there are plenty of requirements that disallow it. Not every requirement in any of the codes is located where you might think or expect it. You would need to look at the situation and determine what all might be applicable and then check those sections.
The very first is NEC 408.41 (see above) that is a basic safety requirement. This is intended mostly to protect the person working on the panel from leaving the second circuit energized while isolating the one being removed for testing. This is the reference that specifically prohibits this condition in your picture.
The second is the obvious reason that apparently to use this technique there are not sufficient tie points on the terminal bars to handle all branch circuits or sloppy/lazy work was done in the panel. This is handled in the following NEC requirements.
It’s always possible that the EGC’s could have been grouped under terminal points to free enough terminal points for one neutral per point. Many terminals are rated for multiple conductors under each point.
These are the manufacturer’s installation and use requirements. Let’s use a Schneider QO load center as an example as it is a common one. You can find the page for a common one HERE. Look at Page 1 of the “Instruction Sheet”, under the “Danger” warning and “Preparation” and you will see the following.
Also if you read through Schneider’s materials you will find the following.
Schneider does not approve of more than one neutral per termination point as required in NEC 408.41
Schneider does not approve of using the ground bar terminal for neutral connections.
As you can see Schneider requires that the Electrician follow the appropriate codes for proper and safe installation. Schneider provides add in bars for many of its panels, if there are insufficient lugs for some odd reason, to properly wire branch circuits to their panels. Well to follow the NEC we can start with NEC 408.41 and 110.12.
Is it possible this is an attempt at creating a Multi Wire Branch Circuit (MWBC) as inferred in previous posts? If so it is completely wrong! The advantage of MWBC’s are to reduce wiring needs in raceways and runs by providing a single neutral run back to the panel. Obviously two neutrals are being run to the panel and they do not meet the NEC requirements for a MWBC. Also you have a number of these double neutrals shown and I seriously doubt they are all MWBC’s in a home. NEC 210.4 and 200.4(B) are requirements for MWBC’s.
Obviously cables are not being grouped and unless you improperly stick your hand into that panel you are not going to be able to identify which are MWBC’s (incorrectly done) to determine if they have trip ties on the OCPD handles. If you would like to read more about the dangers of MWBC’s here are three links with one being Mike Holt’s piece on ECM WEB and reproduced on his Forum. There are good graphics there to help understand MWBC’s.
Multiwire Branch Circuits Can Be Dangerous
Understanding the Dangers of Multiwire Branch Circuits
National Electrical Code – Multiwire Branch Circuit
Pay close attention to the second link (Mike Holt’s forum), the second last line of the article that states NEC 408.21 was added in 2002 and specifies that every neutral entering the panel must terminate in an individual terminal and this is again for safety reasons. You can certainly pigtail a short neutral to the terminal but not combine two neutrals and then pigtail it to a terminal as you have now terminated two neutrals into a wirenut and onto a terminal which is no different than terminating two neutrals under one terminal point from the safety standpoint.
You can believe anyone and anything you want as to whether this is correct or not. HOWEVER believe this, if a problem occurs as a result of this sloppy and dangerous work YOU will be the one contacted when you fail to call it out for further evaluation by a competent Electrician and as a safety hazard. If it makes it to TREC then TREC won’t care one bit what you were told and only what a knowledgeable Electrician or other tells them.
Now if our visiting Electrician would like to provide us the specific NEC references that state the condition you have discovered is acceptable then please do so we can all learn!