Ground bus, Neutral bus seperation vs sharing.

What is the best way to explain why double tapping the either the ground or neutral bus is a problem as well as why mixing the conductors are a problem? I know of a way to explain why you should not use the neutral conductor as a ground conductor even though it may appear logical since they both meet at the panel. but this one is making my head hurt. It is true that both the ground bus and the neutral bus are strapped at the main panel so what’s the problem with neutrals on the ground bus and visa/versa?

https://www.nachi.org/forum/attachment.php?attachmentid=130030&stc=1&d=1459910168

https://www.nachi.org/forum/attachment.php?attachmentid=130031&stc=1&d=1459910184

Ground bus, Neutral bus** separation **vs sharing. (it’s late give me a break)

BTW the green/yellow stripe wire goes to an Eaton CHSPT2ULTRA, Type 2 SPD for AC power protection. Which may or may not be installed correct. Eaton’s installation guide leaves much to be desired. IMHO.

https://www.nachi.org/forum/attachment.php?attachmentid=130040&stc=1&d=1459912773

Should be installed “before the main disconnect” I do not know which side of the main disconnect that means. But there is a picture with a white wire tied to the bus and the green bonded to the panel itself.

A neutral on a dedicated ground bar puts neutral current on the enclosure and creates a shock hazard.

Neutrals and grounds on the same bus in a service panel is not an issue. The neutrals need to be one per hole. Grounding conductors can typically share the hole with other grounding conductors in the correct size ranges and combinations. This was formerly covered in the listing and labeling of the panel. It has since been added directly in the NEC.

OK so in the case of “dedicated ground bar” that would be for instance in a sub panel, or a ground bar like they do on the outside of the house for other equipment to ground to i.e. telecom?

Circuit conductors are not run to the intersystem bond bar.

Thanks Jim