Article 300.20: Grouping neutrals in a different conduit than hots

[noahff]

We have an installation where the hot wires (3 phase, three of each phase) were installed in a separate conduit to the respective nine neutrals, and we are concerned this might be in violation of Article 300.20. Conduit is ferrous, and we don't have any shared neutrals. Is this a problem? I think all the fields would cancel out in each conduit. Any help would be much appreciated.

 

[infinity]

These are two wire circuits and the hot and neutral of each circuit must be installed within the same ferrous raceway.

 

[jaggedben]

That installation is exactly what 300.20 prohibits. The fields will not cancel out and you could have inductive heating of the conduits.

 

[noahff]

Ok, thank you. Glad that it's pretty cut and dry