Taps

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bwyllie

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MA
Is anybody familar with this situation, a contractor has stated that the local AHJ will accept tapping the Main switchbooard's bus and installing a 600A switch approx 50' away as long as the conduit from the switchboard to switch is encased in concrete. I cannot find in the code where this would be allowed and don't know if I am overlooking something.

Thank you
 
Re: Taps

Once you encase a service conduit in concrete the NEC considers the conductors to be 'outside' the building, 230.6. So that part of the job would be NEC compliant.

The thing that strikes me as a violation is the grouping of disconnects required by 230.72(A). 50 feet away does not seem grouped to me, but ultimately I guess that is up to the inspector.
 
Re: Taps

This would be ok if the tap is made before the Main Switch,if any I need to confirm this. What if he tap occured after the main switch, are the conductors still considered outside of the building?
 
Re: Taps

If the tap is made after the main switch, those conductors are now feeders and are not service conductors. The requirements to follow are in 240.21. Unless this is an industrial establishment, I do not see how this is code compliant.

If the conductors are tapped on the supply side of the service disconnect, they are service conductors and the disconnect for them should be grouped, regardless of the concrete encasement.

Pierre
 
Re: Taps

What would be the logic of considering service conductors outside a building when encased in 2" of concrete but not considering feeder conductors the same way?

230.6 while in the Services article I believe is giving a general definition to conductors considered outside.

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
Click to expand...
In 230.6 they do not say service conductors, the code sections around 230.6 spell out service conductors or service raceways.

I do not believe this is semantics or a mistake.

It make no sense that I could run service conductors unlimited length encased in concrete but not allow this for feeder taps.

Does anyone have some inside info on this from ROPs?

Bob
 
Re: Taps

I would want this in writing. It seems to me that the inspector (or the contractor) is engineering the system, contrary to code. Something doesn't seem right here. Have an electrical engineer draw me up a set of plans, send it through plan review at the BOs office, then I'll install it. (This covers my a--)
 
Re: Taps

Service conductors do not have overcurrent protection at their point of connection (hense keeping these conductors 'outside' the building), in general feeder/branch circuit conductors do. There is less need to be concerned for the feeder/branch circuit conductors because of this.
Because of this, 230.6 exists in Art 230 and is not general to all of the code book requirements.

Section 240.21 and the subsections for feeder taps are very specific, and if they wanted to permit concrete encasement as part of the requirements, I believe it would be stated there. Maybe there is room for a proposal there :) .

Pierre
 
Re: Taps

Originally posted by pierre:
Section 240.21 and the subsections for feeder taps are very specific,
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I agree and IMO 240.21(B)(5) allows this when you also take into account the definition of conductors considered outside a building 230.6.

90.3 Code Arrangement.
This Code is divided into the introduction and nine chapters, as shown in Figure 90.3. Chapters 1, 2, 3, and 4 apply generally;.......
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Unless 230.6 specifically said service conductors IMO it applies to all conductors. :)

I would get some more opinions before I counted on that though. :p

Bob

[ July 04, 2004, 08:48 AM: Message edited by: iwire ]
 
Re: Taps

Bob,
Review the scope statement of Article 230. This article does not apply to feeders.
Don
 
Re: Taps

Thanks Don I will by that.

I still have a couple of questions.

I wonder why the sections on each side of 230.6 specifically refer to service conductors or service raceways while 230.6 only refers to conductors?

I also can not understand why the lesser protected service conductors can be outside when encased in concrete but the greater protected feeders can not be.

But as you told me before "Who says it has to make sense" :D

Happy 4th

Bob
 
Re: Taps

As far as the AHJ's position, I would say they are using the second paragraph of 90.4 to approve this, and I appreciate this type of common sense still existing in inspection / approval procedures. I would like to think they have evaluated the whole scenario and sees this as safe.

Roger

[ July 04, 2004, 12:39 PM: Message edited by: roger ]
 
Re: Taps

I understand why you may have an occasion to need a service considered outside the building. Why would you ever need a feeder classified the way?
Example?
 
Re: Taps

I thought the opening post was example of such a need.

Say there is no room in the electric room for another 600 amp switch. :)
 
Re: Taps

Sounds like the origional post was describing a service outside the building not a feeder.
 
Re: Taps

Thanks for all the responses. I have not visited the site yet due to the holiday, but this tap and concrete encasement will be inside the building. I will update you with what I find.
 
Re: Taps

Iwire and Don:

I think 230.6 applies to feeders and branch circuits. I know that 230 deals mostly with services, but look at 230.3 and 230.9 for example. They specifically say "SERVICE conductors". 230.6 only says "Conductors".

Like Iwire said, it just makes sense that if this applies to service conductors, it would apply to feeders, etc.

If this doesn't apply to feeders, then what is the definition for "outside feeders". Each AHJ would have to use their own judgment. And I think that takes them right back to 230.6 for the only guidance the NEC provides.

Steve
 
Re: Taps

Steve,
The only thing within the scope of Article 230 is services. Feeders are not within the scope of that article and none of the rules in that article apply to feeders. 230.6 is referenced in other sections of the code to define conductors that are "outside of the building". 240.21(B)(5)(4)(c) is an example and is the code reference that applies to the original question in this thread. Other references to 230.6 include 225.32, 240.21, and 695.6.
Don
 
Re: Taps

The plan for this installation is to tap BEFORE the main switch, therefore making this a service tap and encasing the conduit in concrete it will be outside. Due to space limitation the local inspector will allow the second switch to be installed in the new electric room(approx 50' away) as long as signage is installed at each switch. Thanks for all your responses, I too find it confusing to the exact definition of an "Outside feeder" as defined by the code, I would think since the service is considered outside when encased why wouldn't a feeder, hopefully the 2005 code will offer some clearier definition.
 
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