Minimum Cover Requirements, Table 300.50

[manuel bonilla]

When using Table 300.50, in a 19.9/34.5kV three phase circuit, what is understood as the circuit voltage? Is it the voltage of ungrounded conductor to ground (19.9kV)? Or is it the the voltage between phase conductors (34.5kV)?

Also, if I want to install RNC under a building slab, does column 4 (4 inches) prevail over column 2 (18 or 24 inches)?

 

[chris kennedy]

300.5 is 600v or less. Sounds like you need to talk to POCO.

 

[manuel bonilla]

My Table 300.50 NEC 2005 is for over 600V.

Maybe you are confused with Table 300.5

 

[chris kennedy]

Thank you moderator, Manuel 300.5 is my area. When I read 300.50 IMO column 4 would be your application.

 

[iwire]

Chris it does not strike me that manuel will be doing the installation.

 

[LarryFine]

Is it the voltage of ungrounded conductor to ground (19.9kV)? Or is it the the voltage between phase conductors (34.5kV)?

My best friend who is an EE in HV and MV distribution, says that system voltage is always given as the line-to-line voltage.

 

[don_resqcapt19]

Article 100
Voltage (of a circuit). The greatest root-mean-square (rms) (effective) difference of potential between any two conductors of the circuit concerned.

 

[manuel bonilla]

Also, if I want to install RNC under a building slab, does column 4 (4 inches) prevail over column 2 (18 or 24 inches)?

What would be the answer to this. In my opinion column 4 would prevail.

 

[Dennis Alwon]

What would be the answer to this. In my opinion column 4 would prevail.

It's not a matter of prevailing or not. It is your option. Either one would work. So if you have 4 inches of concrete then you don't need to go down 18".