600v rated cable support in concrete pit

[zeilzabob]

I have a 4000 amp 480v service and below is a concrete pit approx 10' wide 5' deep and 25' long. Engineered steel structure for the service to sit upon on top. The idea is to bring feeder conduits into the pit and then free air from where it enters to the associated branch breaker. In some cases this will span 20'. I cannot find in the NEC the support requirements for the cabling within the pit. I see in 328 its 6' but I do not find anything for 600v rated cables. Any help is appreciated.

 

[tom baker]

That's because what you are proposing is not allowed. Conductors are required to be used with a chapter 3 wiring method.

 

[infinity]

Sounds like you might need a cable tray.

 

[zeilzabob]

According to a local electrical engineer it falls under 328.30 new for 2017. Since the MV grounding conductor is run with MV cable and approved to be routed with the 6' support rule these would fall under the same rule.

 

[nhee2]

Are you using MV cable for the 480 V install?

 

[zeilzabob]

480v install. But the grounding conductor that would be pulled with the MV cable is 600v rated and required to accompany. That is where he is getting the interpretation.

 

[tom baker]

Are you getting this inspected?

 

[zeilzabob]

The facility was already inspected and signed off on. It was just recently brought up as a question.

 

[tom baker]

Did the inspector see the wiring in the pit?

 

[zeilzabob]

The inspector reviewed the pit, and the switchgear sitting above. I am unsure if he had seen how the cabling was supported. There was conversation on the pit and gear and there was no issue with it at that time.