Focus on the Code

250.148 Metal Box Bonding

Let’s address questions that have been raised about the allowed methods to comply with section 250.148 when installing branch circuit wiring with devices in metal device boxes

Questions from the field

Questions From the Field

I am having trouble interpreting Section 705.12(D)(3) [NEC 2011] and the exception to 705.32. Specifically, I am having issues with the exception.

Photo 1. Installation of large electrical service equipment

Electrical Questions from the Field

My accomplices and I have made up a mock service diagram to be used in an educational program.  The electrical service is rated 4000 amps at 120/208 volts. We are supplying the service equipment with 12 sets of 600 kcmil aluminum type THWN per phase.

Code Questions: 690.64(B)(2)

My main concern for this particular installation is in reference to 690.64(B)(2). The new 400-amp subpanel is being supplied by 400-amp disconnect which is fed by a line side tap ahead of the service-main disconnect.

Sole Connections

Are there any provisions in the NEC that address the de-energizing of rooftop photovoltaic (PV) wiring in an emergency situation for first responder emergency personnel?

What’s Happening to Table 310.15(B)(7)?

Would addition of the control circuit conductors in one conduit of this power circuit run in parallel be a violation of having the same number of conductors and the same electrical characteristics

Dry-Type Transformer, Grounding & Bonding Terminations

Are there any practical guidelines available to installers and the enforement community with regards to continuous loads?