250.21(a)(4)

[Pinnie]

Subtext under the picture says ungrounded systems in hospitals are typically single phase two wire. Is that true? Grok disagrees.

 

[roger]

Don't trust Grok, it's true see 517.160

 

[Pinnie]

Don't trust Grok, it's true see 517.160

That’s why I came here thank you

 

[don_resqcapt19]

While single phase two wire is the most common hospital isolated systems, there are 3-phase systems and 517.160(A)(5) provides the required colors to be used for the identification of the conductors of a 3 phase isolated ground system.