ECN Forum Forums Code Related Discussion NEC & other Code issues Manholes

Fiber does not count in those ampacity calculations but they do count for fill.

Common practice here is that the MV duct bank is only for the MV. Data/Comm conduits are seperated from the duct bank.
Last projects, the Data/Comm was 48" away from the duct bank.

Again, this falls back to the design professional.

I agree it is a good design choice to keep "copper" data 3 or 4 feet away from power but I am not sure it is code and I am not sure you actually need to do it from a data integrity standpoint.
You do want to keep the data GUYS away from MV. I would not terminate those data raceways in a MV manhole.(not even a condolet)

Thanks for all the helpful comments. @ Greg...the reason the conduits are sloped towards the manhole is because there is a problem with freezing water trapped in PVC that can separate the conduits...these manholes have a
2% slope in the bottom and have a drain...

Thanks for all of the other references for separation on ductbanks...a lot of these contain only fiber..so no copper in the other conduits.

Thanks for any further input greatly appreciated..my books will be arriving soon!

Are we talking about the duct bank or the surface grade?
I guess I misunderstood and thought you meant the manhole cover was at the bottom of a 3% grade.

Greg, This is a duct bank feeding into an 8 foot by 8 foot by 8 foot manhole. it has thre components...a base, the manhole and a top with a steel manhole cover in the center of the top. it has a ladder inside...

the specs call for a 0.3% slope towards the manhols. The feeder is a 4160 kV in a 4" conduit and two two inch conduits with FIBER OPTICS.

I have other duct banks that are placed on plastic spacers...
Article 310.60 seems to say you need 7.5" of separation between conduits containing power..

I am having trouble finding what the spacing is on 4 conduits containing 4160 VAC circuits...is it 7.5 inches?

thanks

Greg