Originally Posted By: roconnor This post was automatically imported from our archived forum.
jtedesco wrote:
... Inspector calls for the "service entrance raceway to be encased in concrete!"
bbadger wrote:
The inspector is within the bounds of the NEC to require this.
Bob ... I am not following. NEC 230.32 would allow service conductors in a building to be protected with either concrete encasement or an approved raceway ... like metal conduit, which that appears to be from what is left exposed.
I don't see it, unless that is not an outside wall a few feet away ... and those were service tap conductors exceeding the 25' tap rule. Then the concrete encasement may be required under NEC 230.6.2 to reduce the effective length of the conductors "within the building".
-- Robert O'Connor, PE
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I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: bbadger This post was automatically imported from our archived forum.
Robert here is how I see it.
230.70(A)(1) Requires the service disconnecting means to be nearest the point of entrance of the service conductors.
230.6 Explains the when a service conductor is "outside" a building.
Service conductors can run as far as you want inside the building and still be considered by the NEC to be outside the building if encased in 2" of concrete. 
Quote:
230.6 Conductors Considered Outside the Building.
Conductors shall be considered outside of a building or other structure under any of the following conditions:
(1)Where installed under not less than 50 mm (2 in.) of concrete beneath a building or other structure
(2)Where installed within a building or other structure in a raceway that is encased in concrete or brick not less than 50 mm (2 in.) thick
(3)Where installed in any vault that meets the construction requirements of Article 450, Part III
(4)Where installed in conduit and under not less than 450 mm (18 in.) of earth beneath a building or other structure
Many areas will not allow one inch of service conductors inside the building, other areas like the one I am in will let me go about 4' to 6' inside the building with SE cable, or raceway before I get to the disconnect.
However this is not in writing and you can always have an inspector say no way.
Bob
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: roconnor This post was automatically imported from our archived forum.
Although 230.70 concerning a disconnect being nearest the point of entry is interpretive, IMHO 230.32 specifically allows service conductors in conduit inside a building.
So I think an inspector who will not allow one inch of conduit inside a building is really way out on a very thin limb, and that wouldn't fly around my neck of the woods. But you are right that the interpretation is up to the local AHJ, no matter how unreasonable it may seem to be ... 
Just my opinion and 2-nickels ...
-- Robert O'Connor, PE
Eagle Engineering ?
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I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: roconnor This post was automatically imported from our archived forum.
roconnor wrote:
IMHO 230.32 specifically allows service conductors in conduit inside a building.
bbadger wrote:
I respectfully, strongly, disagree with that.
Bob ... The intent of that quote was that while there are (vague) restrictions on the length service wires in a building, there are specific provisions for service wires without concrete encasement inside a building subject to those (vague) limitations. IMHO, If the provisions of 230.32 were not in the model code, I would tend to agree with a very restrictive position of service wires not being allowed within a building unless encased in concrete.
While service conductors do not have overcurrent protection, I would think the real risk of vaporizing conduits is with higher voltage commercial services (where a more restrictive position may be more reasonable due to the greater risk of injury or fire), and not with the typical 240/120V residential service in homes an HI would encounter.
Just my opinion and 2-nickels ... 
-- Robert O'Connor, PE
Eagle Engineering ?
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NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: pdacey This post was automatically imported from our archived forum.
Wow, two professionals with different opinions having an inteligent civil conversation. Go figure.
Thank you to the both of you Robert and Bob. I always learn something new when reading your posts. Kepp it up. 
Originally Posted By: bbadger This post was automatically imported from our archived forum.
Thank you Patrick.
Robert while you are correct that a 480 volt service has higher arc fault potential a simple 240 house service can make conduit and wires disappear.
The POCO simply does not protect the secondary wires running to a house, if your lucky the connection between the utility wires and the home owners service conductors will burn clear.
If it does not burn clear nothing will stop the current from destroying what ever is "in the way"
Have you ever welded?
If so you know how much metal you can melt with 100 amps @ about 70 volts.
Now think about a 1000 amps (or much more) @ 120 volts (the voltage to ground) believe me no metal raceway will contain the fault.
We will have to agree to disagree on this one,  maybe some others will jump in on this.
Back to the higher current services.
We had a good one on a 1200 amp 480 service, it melted all three 4" rigid metal conduits back toward the transformer like a wick for about 30' luckily this was on the outside of a block building.
The utility fuse did not blow until the oil in the transformer boiled over and the primary winding in the transformer melted.
Big bang
Bob
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: roconnor This post was automatically imported from our archived forum.
bbadger wrote:
We will have to agree to disagree on this one,  maybe some others will jump in on this.
I might be off here, as I am just going by perceptions and general information. Would be good to have some input from someone who really knows the POCO side.
-- Robert O'Connor, PE
Eagle Engineering ?
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I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: Greg Fretwell This post was automatically imported from our archived forum.
This is what the handbook says
No maximum distance is specified from the point of entrance of service conductors to a readily accessible location for the installation of a service disconnecting means. The authority enforcing this Code has the responsibility for, and is charged with, making the decision as to how far inside the building the service-entrance conductors are allowed to travel to the main disconnecting means. The length of service-entrance conductors should be kept to a minimum inside buildings, because power utilities provide limited overcurrent protection and, in the event of a fault, the service conductors could ignite nearby combustible materials.
Some local jurisdictions have ordinances that allow service-entrance conductors to run within the building up to a specified length to terminate at the disconnecting means. The authority having jurisdiction may permit service conductors to bypass fuel storage tanks or gas meters and the like, permitting the service disconnecting means to be located in a readily accessible location. However, if the authority judges the distance as being excessive, the disconnecting means may be required to be located on the outside of the building or near the building at a readily accessible location that is not necessarily nearest the point of entrance of the conductors. See also 230.6 and Exhibit 230.15 for conductors considered to be outside a building.
Originally Posted By: jpeck This post was automatically imported from our archived forum.
bbadger wrote:
roconnor wrote:
IMHO 230.32 specifically allows service conductors in conduit inside a building.
I respectfully, strongly, disagree with that.
Robert,
I agree with Bob, that is the wording and intent.
Encasing in a minimum of 2" of concrete keeps the conductors as being considered "outside" the structure. Anything less and the service entrance conductors are considered "inside" the structure, requiring overcurrent protection "nearest the point of entrance" ... by the way, what is "nearest the point of entrance" in feet?
Originally Posted By: roconnor This post was automatically imported from our archived forum.
jpeck wrote:
... requiring overcurrent protection "nearest the point of entrance"
That is the vague restriction on service wires within a building from NEC 230.70 we were discussing, and Greg posted the NEC Handbook comments on that. Now look at NEC 230.32
Quote:
230.32 Protection Against Damage
Underground service-lateral conductors shall be protected against damage in accordance with 300.5. Service-lateral conductors entering a building shall be installed in accordance with 230.6 or protected by a raceway wiring method identified in 230.43
Why have provisions for the "service lateral conductors entering a building" to be "protected by a raceway wiring method" such as SE cable or rigid conduit for residences, if the intent of 230.70 is that there not be any service conductors within a building, or that it be protected with concrete under 230.6? Many around my neck of the woods use the 25' Tap rule as a guide for a maximum, as long as the conductors are in a separate electrical/mechanical room and reasonably close to where the service enters the building where practical.
Again, I don't see the severe risk for residential services that would warrant writing up exposed SE cables or conduit for encasement in concrete. Do you write those up for encasement?
-- Robert O'Connor, PE
Eagle Engineering ?
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I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jpeck This post was automatically imported from our archived forum.
roconnor wrote:
230.32 Protection Against Damage
Underground service-lateral conductors ...
Robert,
You are offering a VERY limiting reference (which only pertains to protections from physical damage, by the way, to allow for raceways TO the main service disconnect) to refute the statement from 230.70(A)(1)
Your reference, 230.32 ONLY is specifying protection from physical damaged from the point the UNDERGROUND service lateral turn up and comes through the slab (or side wall if a basement). Protection from physical damage must be as prescribed, but the raceway does not allow one to run the service entrance across a house to a main disconnecting means on the far side ... the main disconnect must still be "closest to the point of entrance of the service conductors. I.e., your reference has nothing to do with 'distance' or how far, only with protection "for that distance", and only for underground service laterals.
VI. Service Equipment ? Disconnecting Means
230.70 General.
Means shall be provided to disconnect all conductors in a building or other structure from the service-entrance conductors.
(A) Location. The service disconnecting means shall be installed in accordance with 230.70(A)(1), (2), and (3).
(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.
(2) Bathrooms. Service disconnecting means shall not be installed in bathrooms.
(3) Remote Control. Where a remote control device(s) is used to actuate the service disconnecting means, the service disconnecting means shall be located in accordance with 230.70(A)(1).
Originally Posted By: roconnor This post was automatically imported from our archived forum.
jpeck wrote:
your reference has nothing to do with 'distance' or how far, only with protection "for that distance", and only for underground service laterals.
I agree that 230.32 reference has nothing to do with distance, which is covered with the vague/interpretive 230.70 provisions. I was only disagreeing with interpreting 230.70 that not one inch of service conduit could be run in a building, particularly for a residential service. Sounds like JT is on the same page as me with the tone of the original post, but maybe he will check in on this with his thoughts.
I am also still curious about the POCO side of this issue. The residential service drops/laterals are usually much smaller than the service feeders inside a home. I know the POCO follows the NESC, which allows smaller service wires, but I am curious if this is also intentional to ensure the drop/lateral fries before the feeders inside a home.
-- Robert O'Connor, PE
Eagle Engineering ?
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NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jpeck This post was automatically imported from our archived forum.
roconnor wrote:
I was only disagreeing with interpreting 230.70 that not one inch of service conduit could be run in a building,
Then you are not disagreeing with me. You mean we agree on something? 
Down here, as I stated above, the distance varies from 5-8 feet of conductor length.
Think about that a minute ... meter on outside of wall ... main disconnect on inside of same wall, back-to-back. You've probably got 3 feet of conductor length right there.
Or, come up through a slab to a main disconnect installed at about 6 feet high (to the handle), you've got about 8 feet of conductor length in the structure there.
Originally Posted By: roconnor This post was automatically imported from our archived forum.
jpeck wrote:
Down here, as I stated above, the distance varies from 5-8 feet of conductor length.
Seems pretty common around here too, except in NYC commercial buildings where a bit more is more common ... which I am okay with, as long as it's in a fire separated mechanical/electrical room with clear warnings on the door. But I wouldn't count inside the wall as being exposed inside the building.
jpeck wrote:
Then you are not disagreeing with me. You mean we agree on something? 
Yea, go figure ... us agree on something ... ... we must be slipping. So how about I disagree with you, that it seems you are agreeing with me instead of the other way around ... 
-- Robert O'Connor, PE
Eagle Engineering ?
Eagle Eye Inspections ?
NACHI Education Committee
I am absolutely amazed sometimes by how much thought goes into doing things wrong
Originally Posted By: jtedesco This post was automatically imported from our archived forum.
Hello:
I am in Boston today at Mike Holt's 2005 NEC Seminar and asked a few of the people here, some of which are from NYC, NH, Florida, and other states, most said that there area would allow up to 6-10 feet.
Connecticut might call for an outside main disconnect beyond 6 feet.
The NECH commentary is not new, and reflects the opinions of many in our industry, and was there when I helped to write it as well.
I wanted this question to be discussed, and understood and for the reasons of a correct answer on a test, I wanted to call attention to the "readily accessible" part of the rule.
I live in a 9 story building where the service conductors are installed busways run from the supply to the roof, and that wiring method is not "encased in concrete"
For the HI, it is not necessary to make an issue of this because the inspector accepted it. Be done with it and do take a picture for our archives, please.