200.3?

[bennie]

Will someone please explain to me what this section is referring too?

 

[dereckbc]

Re: 200.3?

From the NEC 2002 Handbook. "Grounded conductors of premises wiring (other than separtely derived systems) must be connected to the supply system grounded conductor to ensure a common, continuous, grounded system."

 

[bennie]

Re: 200.3?

The reason I asked is because I have a book describing the original reason.

The reason as stated in the 1930's, when this first appeared has apparently been changed.

The reason was to prohibit the installation of an auto-transformer as a balance coil to derive a three wire system.

All reference to this was removed from the code book in 1975.

 

[bennie]

Re: 200.3?

I have discovered the reason for removing the section about auto-transformers. It was done due to the use was discontinued anyway. Standard two winding transformers replaced them.

200.3 Is to assure the utility MGN is connected to the X-O of the premises system, for the purpose of winding to winding faults.

 

[bennie]

Re: 200.3?

I have been partly corrected in my previous explanation of my interpretation of 200.3.

A grounded premises wiring system can not be electrically connected to an ungrounded supply, except by magnetic coupling.
Electrically connected shall mean capable of carrying current.