Ground cable in concrete encased duct banks

[FaradayFF]

Hi,

Is a ground cable an absolute necessity to include in concrete duct banks? I understand the function of the ground wire, I'm just wondering, if there are any instances where you'd not include it in the duct bank(lenght of run, cost, ect)?

Thanks,
EE

 

[GerryB]

Are you referring to a "ufer" ground? I haven't seen a ground wire run in duct banks I've been exposed to.

 

[petersonra]

Hi,

Is a ground cable an absolute necessity to include in concrete duct banks? I understand the function of the ground wire, I'm just wondering, if there are any instances where you'd not include it in the duct bank(lenght of run, cost, ect)?

Thanks,
EE

the code generally requires an equipment grounding conductor be run with all circuit conductors. It can be a wire or metallic conduit, but it needs to be there.

 

[steve66]

I'm not really sure if you mean a ground or a neutral? Is it a low voltage duct bank, or a medium voltage duct bank? A feeder or a service?

 

[Julius Right]

In any case a grounding conductor has to run along the cable duct bank for low voltage return fault current .For medium voltage one has to check how the shield can convey the fault current-but just in case a grounding wire will be welcome. For instruments and telecommunication also. However potential transfer has to be avoid [ a grounding mean-rod, ufer etc.in each manhole could be connected with this grounding wire]