Tapping grounded conductor in box

[Gategator37]

Last friday I opened a junction box to finish up some work and noticed that the low volt. guy on the job had tapped on to my grounded conductor without telling me. His control box is located nearby (where his 120v circuit is located), but rather than carrying a neutral over, he only brought his 24v ugrounded conductors. Since my grounded conductor is of a different phase is this illegal? I did try to locate this in the NEC, but am having trouble.

Thanks for the help.

 

[Dennis Alwon]

It depends on what insulation is used, wiring method, etc. Look at 300.3 esp. (B)(3) & (C)(1)