Service entrance conductors concrete encasement

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reko19

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Article 230.6 is pretty clear on what conductors are considered outside of the building. For 600V or less underground service conductors, according to 230.32, I could either install service entrance conductors per 230.6 OR per 230.43 which is NOT concrete encased. For over 600V (article 230.202) i am allowed to install per 300.37 which is NOT concrete encased. Could someone clarify 2" concrete encasement requirement, the way I see it is not required.

Is there a different requirement for a service conductor vs. service entrance conductor?

thank you
 

charlie b

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The 2" of concrete is never a requirement. Rather, it is, on occasion, an opportunity. If the main disconnecting means is inside the building, it is required to be ?nearest the point of entry of the conductors.? In my state, the limit is 15 feet. If the transformer is outside the building, and if the electric room is in the middle of the building (more than 15 feet from the outside wall), then I would run the service conductors under the slab. On a couple projects for which the electric room was in a below-grade level, so that the service conductors had to be run in the overhead of the basement level, I encased them in 2? of concrete. In both instances, the fifteen foot limit for reaching the main disconnecting means did not begin until the conductors were no longer under the slab or no longer within 2? of concrete. What this did for the design is to prevent me from having to install a disconnect close to the outer wall, put the N-G bond at that location, and run the conductors (with EGC) to the main switchboard from there.
 

reko19

Member
The 2" of concrete is never a requirement. Rather, it is, on occasion, an opportunity. If the main disconnecting means is inside the building, it is required to be ?nearest the point of entry of the conductors.? In my state, the limit is 15 feet. If the transformer is outside the building, and if the electric room is in the middle of the building (more than 15 feet from the outside wall), then I would run the service conductors under the slab. On a couple projects for which the electric room was in a below-grade level, so that the service conductors had to be run in the overhead of the basement level, I encased them in 2? of concrete. In both instances, the fifteen foot limit for reaching the main disconnecting means did not begin until the conductors were no longer under the slab or no longer within 2? of concrete. What this did for the design is to prevent me from having to install a disconnect close to the outer wall, put the N-G bond at that location, and run the conductors (with EGC) to the main switchboard from there.
My question is, why did you have to concrete encase overhead conduit in the basement?
 

charlie b

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Lockport, IL
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Retired Electrical Engineer
My question is, why did you have to concrete encase overhead conduit in the basement?
Once the conductors enter the building, I have to hit a disconnecting means within fifteen feet. If I concrete encase the conduits, then they are not yet "inside the building." So I can run them as far as I wish. I design the run such that I come to the end of the concrete encasement close to (meaning within 15 feet of) the main switchboard. The main breaker on that switchboard will serve as the required disconnecting means.

If I did not encase the conduits in concrete, then they would be considered to be inside the building as soon as they entered the basement area. I would then be required to install a disconnect (not necessarily fused) within fifteen feet of the point of entry of the conduits into the basement area. That would involve extra cost and extra inconvenience.
 

reko19

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I can't see where in the code service conductors are required to be outside of the building. I noted in my original post articles which, in my opinion, allow me to run them without the concrete encasement.
 

GoldDigger

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Placerville, CA, USA
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I can't see where in the code service conductors are required to be outside of the building. I noted in my original post articles which, in my opinion, allow me to run them without the concrete encasement.

Look at 230.70(A)A(1) [2011]. The problem is not what form of conductor you are allowed to use, it is where you must put the service disconnect.

(1) Readily Accessible Location. The service disconnecting means shall be installed at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors.
Once you pass the service disconnecting means (and the associated OCPD) the wires are no longer service conductors.
As stated earlier the whole question is how to interpret nearest the point of entrance. Different AHJs will interpret that as being anywhere from 0 feet to 15 feet from the point where the conductors enter the building. Some may even codify it through a local amendment.
So the choice is to
a. keep them short (not always possible),
b. make them not be service conductors (which is exactly the same problem of where to put the disconnect), or
c. keep them "outside" the building under the concrete encased rule even after they come inside the footprint of the building.​
 

charlie b

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Lockport, IL
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Retired Electrical Engineer
Service conductors do not have to be outside the building, although by definition they must originate outside the building. The upstream end of all service conductors is always a utility, again by definition. But I have done projects that have a utility vault inside the building, and service conductors running from that vault to the main electric room. The requirement that is most relevant to this discussion is 230.70(A)(1). That is the article that establishes the required location of the service disconnect. That is where it says that if the disconnect is inside, then it must be close to where the conductors enter the building. It does not give a limit or a definition of "close." So several states have established their own limits. My state's limit is 15 feet, as I have said before. So the whole notion of concrete encasement of the service conductors is merely a design choice that I can make, in order to deal with the 15 foot limit.
 

iwire

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Location
Massachusetts
I can't see where in the code service conductors are required to be outside of the building. I noted in my original post articles which, in my opinion, allow me to run them without the concrete encasement.

230.71(A)(1) requirement for the service disconnect to be nearest the point of entrance is what can trigger the need to use the rules in 230.6.

Different areas interpret 'nearest' differently. Some areas don't allow more that a few inches of service conductors inside, my area allows about 5' and as charlie mentioned his area allows 15'.

Now what happens if you want to place the service disconnect further into the building? You can use the rules of 230.6 to treat the conductors as outside when in reality they are inside.
 

reko19

Member
Ok, got it. I have a case similar to the one described by Charlie. Except it is an industrial 5000A service. Is there an exception I could use, or do I have to concrete encase a 5000A conduit bank suspended from a slab above? Thanks for your help
 

iwire

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Location
Massachusetts
Ok, got it. I have a case similar to the one described by Charlie. Except it is an industrial 5000A service. Is there an exception I could use, or do I have to concrete encase a 5000A conduit bank suspended from a slab above? Thanks for your help

No exceptions I can think of.

Options are installing an additional disconnecting means or concrete.
 
The 2" of concrete is never a requirement. Rather, it is, on occasion, an opportunity. If the main disconnecting means is inside the building, it is required to be ?nearest the point of entry of the conductors.? In my state, the limit is 15 feet. If the transformer is outside the building, and if the electric room is in the middle of the building (more than 15 feet from the outside wall), then I would run the service conductors under the slab. On a couple projects for which the electric room was in a below-grade level, so that the service conductors had to be run in the overhead of the basement level, I encased them in 2? of concrete. In both instances, the fifteen foot limit for reaching the main disconnecting means did not begin until the conductors were no longer under the slab or no longer within 2? of concrete. What this did for the design is to prevent me from having to install a disconnect close to the outer wall, put the N-G bond at that location, and run the conductors (with EGC) to the main switchboard from there.

Over on the other side of the state, I routinely get stuck with local inspectors that believe the WAC means 15 ft "inside building lines", which has lead to some fun discussions with architects about why the electrical room needed to move to an exterior wall instead of in the wall.

While I know the inspectors are wrong, and I've had the argument many times with my boss, I get overruled in favor of not rocking the boat.
 
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