300.37

[m sleem]

In transformer vaults, in higher levels can we run the MV cables in the foundation which is above ground by referring to 300.37 ?

 

[m sleem]

In transformer vaults, in higher levels can we run the MV cables in the foundation which is above ground by referring to 300.37 ?

May be the question is not clear enough, we have located the elec substation at the 11th floor & all of the cables particulary the MV cables were designed to be top entry, now the contractor proposes a sufficient foundation above the floor level for the unit substation (RMU-TR-LV) to accomodate the MV cables, the contractor says no issue in this installation without citing any code section, may be he is right as per 300.37 but i'm not sure, i appreciate any feedback.

 

[Smart $]

The first question in my mind is whether these are service conductors?

Next, where do these MV cables originate and what wiring method is used to get them to the 11th floor?

I don't see how a foundation enters the picture. In my mind, a building foundation cannot exist above ground... much less on the 11th floor. :blink:

If by foundation you mean vault, the entire "substation" can be located in a transformer vault. See Article 450, Part III for the requirements. While I'm aware of and have worked in what I'll call "transition vaults" under exposed transformers, the concept of a transition vault over the top of an exposed transformer just boggles my mind. :happyyes:

 

[m sleem]

The first question in my mind is whether these are service conductors?

These are 13.8kv feeder conductors.

Next, where do these MV cables originate and what wiring method is used to get them to the 11th floor?

I don't see how a foundation enters the picture. In my mind, a building foundation cannot exist above ground... much less on the 11th floor. :blink:

All the 13.8kv feeders are supplied by the MV switch-gear where is located in the sub-basement level and terminated at several substations in different levels, i highlighted only the 11th level which it typical for all.All the 13.8kv feeders are runing in dedicated shafts with barriers to isolate the emergency from normal feeders. BTW, it was not my question


The contractor proposes a foundation/platform above the floor level to carry the equipment as well as to run the cables inside.

 

[Smart $]

... BTW, it was not my question

That's right... 'twas mine. FWIW, I felt it may have had bearing on answer to your question.

The contractor proposes a foundation/platform above the floor level to carry the equipment as well as to run the cables inside.

As noted in 300.37, MV cables are permitted to be run exposed where accessible to qualified persons only.