208V thru a 480V panel

[james blake]

Hey guys. A co-worker and I are changing out an existing 480V fed oven for a 208V fed oven. The 480V and 208V panels are side by side in a block wall with a unused nipple between the two. We were going to feed from the 208V panel thru the 480V panel to the existing raceway, referencing 300.3 C1 and 312.8. My supervisor thinks its a violation. Is there something my co-worker and I are missing?

 

[augie47]

Other than the Articles you lised, I know of no Code reference prohibiting what you plan.

 

[tkb]

The two articles that you reference allow this installation.

300.3(C)(1) as long as the wire for the 208 system is rated for at least 480 volts, I assume you will be using THHN that is rated for 600 volts.

(C) Conductors of Different Systems.

(1) 600 Volts, Nominal, or Less. Conductors of ac and dc circuits, rated 600 volts, nominal, or less, shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway.

312.8 as long as there is sufficent space in the gutter of the panelboard for the wires and it doesn't create more than 75% fill. (very hard to do)

312.8 Switch and Overcurrent Device Enclosures with Splices, Taps, and Feed-Through Conductors

The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met:

(1) The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the cross-sectional area of that space.
(2) The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.
(3) A warning label is applied to the enclosure that identifies the closest disconnecting means for any feedthrough conductors.

 

[james blake]

Thank you for the responses guys!