Romex to your amp?

And, It IS federal law. 

NO. The NEC is NOT Federal Law.   If it was a Federal law it would be a CFR (Code of Federal Regulations) and it's not.   Local building codes are also not laws.  Local building codes generally reference national codes like the NEC and NFPA 101 as the basis of the local code.  Local codes may add additional requirements to the NEC, but rarely delete a requirement.

The NEC is also NFPA 70 (National Fire Protection Association) code.   There is no police agency that is going to enforce the NEC/NFPA 70.  Police agencies enforce laws, not building codes.  There is no direct punishment if you decide to not adhere to the NEC.  There are certainly liabilities and that may result in consequences of not following the NEC, but those are not direct punishments for not adhering to the NEC.

The NEC forms the basis for local electrical codes as part of local building codes enforced by the Authority Having Jurisdiction (AHJ).  In most areas in the United States that is generally a local government agency with a title like "Planning & Development Services Department," or "The City of XXX Planning and Zoning Department," etc.  This is not a police agency with the authority to arrest and detain people.

Codes are enforced by the AHJ through construction inspections. If the inspection shows that the installation does not meet the local building code - nobody is arrested, and no one is going to jail.  If your installation does not meet code, you cannot proceed with additional work until the work is corrected and inspected for conformance to the building code - that's it.

Most electricians will not do work that violates the code because they can lose their license, and be held liable for any damages associated with the non-conforming work.  If the damages can be proven to be the result of performing work that does not conform to local building codes and the NEC, then their liability insurance will not cover the settlement - meaning they have a lot to lose professionally and personally if they do non-conforming work.  

Not quite right...the zoning departments do have the ability to enforce zoning compliance.

I never said they didn’t have the ability to enforce zoning compliance which is totally different than complying with a building code. I was addressing the NEC - and not compliance with ZONING ORDINANCES which are different than building codes.

If you put up a building in conflict with a zoning ordinance, such as a commercial building in an area zoned residential - then, in all probability, the building department will make you remove the structure as it does not meet the zoning requirement for that area.

You seem to be conflating a zoning issue with a code violation - not the same thing.

However, you are correct, in that the AHJ can make the contractor either fix or completely remove and replace work that is not building code compliant.

How the work is corrected is at the discretion of the AHJ. If it’s simply redoing connections in five junction boxes - that’s one level of correction. If the AHJ directs the contractor to remove and replace all of the wire for all of the circuits because it’s the wrong type or size - that’s a different level of correction.

The statement was made that the NEC is a Federal Law - it is not. That’s all I was addressing in my post.

You somehow conflated that with zoning - a completely different building issue and it’s hard to see how a builder or client would get plans approved and permits issued by a building department if they did not meet the correct zoning requirements.