Underground 13.8KV Duct Bank 1

[andysherrill]

I work in an industrial facility where all of our 13.8KV incoming feeders are routed in duct banks with large concrete manholes for pulling and splicing feeder taps. These manholes are spaced at approx. 600' intervals. I am working to add two new incoming feeders. We have not added any duct bank since I started working here, so I don't have any experience. Are there more economical solutions than the concrete manholes? I have had one contractor mention fiberglass manholes, but I don't know anything about this option. Any ideas would be greatly appreciated.

 

[EEJaime]

The cost of precast concrete manholes is not excessively high. It is an industry standard form of construction. It is possible to get any necessary configuration and size. Further, it allows your facility to maintain consistency in it's installation. With manholes 600 feet apart there are going to be requirements for pulling irons, steps, cable racks, etc..., things you might be able to find in other types of manholes, but I don't know that for a fact. Additionally, I am not certain that you would be saving a lot of money by going to another material. I don't know what your location is, but you can get information on the concrete manholes from Associated Concrete Products, Quikset, Utility Vault Co. etc....

 

[dpc]

I agree - precast concrete is the norm. Some massive ones are poured in place or sectionalized, but precast is much easier.

If you're thinking fiberglass or some other material, don't overlook the very real issue of manholes floating up out of the ground when the water gets high. If you have a high water table, this can (and has) happened, even with concrete. I'd get a consult from your local geotech or civil engineer.