Utility Vault Clearance

[saladhawks]

I have searched both the NESC C2-2007 and the California General Order No. 128 concerning any required clearances above utility subsurface enclosures installed on private property.

This specific application involves a utility subsurface building tranformer room installed on private property in the basement of a large mixed-use commercial building. The building transformer room has a 5' x 8' hatch located at finished grade outside of the building first-floor footprint. In the infinite wisdom of the architect, a second floor patio has been installed above the hatch, with about 8' of clearance from the hatch to patio. I want to tell the contractor to remove the patio, but wanted to support my request with a code reference.

 

[alehman]

I've never heard of such a requirement. One has only to read one or two stories of manhole explosions and flying manhole covers to realize this might not be a good idea.

http://www.foxnews.com/story/0,2933,342010,00.html

http://query.nytimes.com/gst/fullpage.html?res=9B07EFDF113AF930A25750C0A9679C8B63

 

[Morrand]

Aside from the question of flying manhole covers, there are more practical concerns. How tall is the equipment in the vault? Will the repair crew later be able to get it out without demolishing the patio? What kind of rigging will they need in order to accomplish that?

Code or not, it's not usually a good idea to make outage repairs involve major demolition.