Duct Bank Stub Up to Existing Outdoor Gear

[smoothops10]

I have seen a lot of utility regulations around in my locale where the requirement to install a new low voltage service from an existing utility owned padmount transformer is as follows:

1. Electrical contractor installs duct bank from meter socket or CT cabinet to within 3' or 5' of existing utility transformer
2. Electrical contractor contacts utility to coordinate install of final 3' or 5' run and stub up of duct bank in to transformer
3. Service entrance conductors are furnished and installed sometimes by EC and sometimes by utility

My question is in regards to item 2. I am having a hard time envisioning how this is done. How exactly is this final stub up performed? Is there a big hole dug around the front of the transformer and duct bank work is carefully done? Is the transformer lifted to allow this work to be done? If the transformer is on a concrete pad, how do they coordinate this install? Who actually performs this last 5 feet and stub up? If anyone has pictures or a description it would be appreciated.

I'm asking not specifically in regards to utility services but I am working on a design that requires getting a 5" or 6" conduit underground in to an existing piece of outdoor metal enclosed gear. The previous designer included no spare ducts in to this gear.

 

[Julius Right]

Something like this, it may be?

 

[Cow]

I'm not trying to come off harsh, but this is a prime example why an engineer should have field experience before becoming an engineer.

To answer your question, if the transformer is sitting on a vault we would simply blow another hole through the side of the vault most likely with a roto hammer or sledge. Slip the conduit in, slap a bell end on and spray foam around the conduit. If the transformer is on a pad, we would undermine the pad very carefully and slip the 90 up into the transformer and backfill it. If transformer/outdoor gear is on a concrete pad and surrounded by a slab, a person would most likely hire a concrete cutter and excavator operator to cut a trench in the concrete to the gear/transformer. You would most likely undermine the gear if you weren't able to cut the trench all the way into the bottom of it. Then you would core drill a hole through the gear pad into the trench below it and slide a 90 up through the hole.

You never want to undermine the back of the transformer if you can help it, that's where all the weight is.

At least this is how I do it...