CT cabinets

[Danielt]

230.70 says the service disconnecting means shall be located "either outside of a building or structure or inside nearest the point of entrance of the service conductors." So this allows the unfused conductors to come out of the floor inside a building, going straight into a disconnect, a panel with a main, or switchgear. Does this mean a CT cabinet or feed-through meter cannot be in the building? With an indoor CT cabinet, the disconnecting means is not at the nearest point of entrance. Am I seeing this clearly?

 

[Tyler C]

The requirement is not for the service disconnect to be the first piece of equipment the service entrance conductors enter once inside the building, it is only that the service disconnect(s) is/are nearest the point of entrance, meaning that it is located physically close to where the conductors enter. How close is "nearest" has always been an area subject to interpretation, with different AHJs handling it differently.

I have seen services with indoor CT cabinets, where the service disconnect was immediately adjacent to or right above the CT cabinet.

You of course could also have CTs inside a service switchboard that is indoors.

 

[Danielt]

It seems to me the intent of the code is to limit the amount of unfused conductors inside a building . The code is from the NFPA, so that interpretation makes sense to me.
When they go straight into switchgear, CT section or not, that is okay.
Our power provider won't allow CT cans to be low, below the disconnect, I'd be happier with that.
I've seen contractors encase the conduit to the CT can, which is a lot of work, but to me this satisfies this code. Maybe I'm being over zealous.
So if you allow a CT can inside, is there a limit on the length of unfused conductors?

 

[roger]

So if you allow a CT can inside, is there a limit on the length of unfused conductors?

It's entirely up to your AHJ and the rules they have set up.

 

[Tyler C]

I've seen contractors encase the conduit to the CT can, which is a lot of work, but to me this satisfies this code.

Concrete encasement is explicitly permitted by 230.6. When the service entrance conductors are concrete encased, they are considered outside of the building. This is frequently done in cities where the conductors may be entering from the utility on the first floor or cellar level. Space is often limited on these floors (lobby, loading dock, exit discharge, etc.), and any remaining space has better use being rented to a retail tenant than as a service room. Because of this, it is often desired to put the service room on a different floor (maybe 3rd or 4th floor), so to comply with 230.70, the service entrance conductors are concrete encased up a few floors, so then they "enter the building" in the service room.

 

[Eddie702]

The Code never gave an explicit length for unprotected conductors. Rule of thumb for residential (around here is/was 10' 1 stick of pipe). I had a residential job where on the wall the entrance came in there was a 4" sewer line running across the wall. I didn't want to build the panel out from the wall 6" so I came out of the meter socket with Rigid and went across the room to the panel and the inspector was ok with it.

 

[Danielt]

So it seems reasonable, based on NEC 230.70, when service conductors enter a building, they must go immediately to the disconnecting means. If they first go to a CT can is inside the building, the conduit must be encased per NEC 230.6.

 

[electrofelon]

So it seems reasonable, based on NEC 230.70, when service conductors enter a building, they must go immediately to the disconnecting means. If they first go to a CT can is inside the building, the conduit must be encased per NEC 230.6.

I would not say that. Many switchboards have a metering section that the conductors hit before the service disconnect. You simply will not find a specific answer in the NEC. IF you need a specific answer, ask your AHJ.