OKAY...LETS STIR THE POST SOME

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pierre

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Westchester County, New York
NEC

" VI. Service Equipment - Disconnecting Means

230.70 General. Means shall be provided to disconnect all conductors in a building or other structure from the serviceentrance 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."


For Guidance:
Chapter 8, A definition for POE

"Point of Entrance.
Within a building, the point at which the wire or cable emerges from an external wall, from a
concrete floor slab, or from a rigid metal conduit or an intermediate metal conduit grounded to an electrode in accordance
with 800.40(B)."


Okay, my point :)

Service entrance conductors entering a building.

We have seen that there are many different ideas as to how far a set of service entrance conductors can travel into a building before a disconnect is required. 5', 10', 15' in some jurisdictions.

If I can come into the building any of those distances, why not further? Why not 25', why not 50'?

What is the difference between 5' or say 15', which we know some jurisdictions permit, why not more.
Once the conductors are in the building I do not see what the difference is (I don't think current will know the difference either). 1' just into the building will cause the same problem just as the 1' portion that is 7' or more inside the building.


"...inside nearest the point of entrance..."

What does that really mean?
What is the real reason that this disconnect is being installed?

[ October 14, 2005, 08:04 AM: Message edited by: pierre ]
 
Re: OKAY...LETS STIR THE POST SOME

Originally posted by pierre:
Once the conductors are in the building I do not see what the difference is (I don't think current will know the difference either). 1' just into the building will cause the same problem just as the 1' portion that is 7' or more inside the building.
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Imagine a 1' long trail of gasoline ignited in an attic. Someone might spot it and catch it in time before it kills people and destroys the building.

Imagine a 50' trail of gasoline ignited in an attic. How much less response time does the FD have? How much more is destroyed when the match is struck?

That's my guess.

I don't care: Around here, it's pretty much viewed as written, which suits me fine. :D
 
Re: OKAY...LETS STIR THE POST SOME

In my area of work, the limit from POE to service disco enclosure is five (5') feet measured along the cable or raceway.

It is significant that there are ways to stretch this distance by playing with where the POE is defined as being. Especially by encasing in 2" or more of concrete.

Most of the time, with a little head scratching, I can come up with a work around that avoids a special pour, but, I could run 50' across the first floor with the concrete encasement if it pleased the customer.

The idea of the 2" of concrete and raceway being able to contain a set of service entrance conductors that are burning like a fuse, that the PoCo OCPDs just won't dump, is questionalble in my mind. . .but it is Code.
 
Re: OKAY...LETS STIR THE POST SOME

I have always thought that the disconnect was there to protect the utility company. Before it was an OCPD belonging to the POCO that was responsible for protecting the building and now the OCPD belongs to the owner. I don't know that any POCO's have been blamed for any house fires but I can see where a smart lawyer could try and make a connection.
 
Re: OKAY...LETS STIR THE POST SOME

My 2?-- in my area the rule is 8? maximum. I suspect the different lengths are there to accommodate the EC. When you have an exisitng structure and the exterior wall is full of ?stuff,? or the structure itself is not user friendly, you have some leeway as to where you can place the panel (w/ MB) or the first OCPD.
 
Re: OKAY...LETS STIR THE POST SOME

I consider the nearest point of entrance to be the location that is most suitable, practical, and reasonable. That being said, this may indeed mean one specific structure will have 5' of service entrance before the disconnecting means, and another might have 10'. The point is that if I feel the "allowance" is being abused simply for the convienence of the contractor or the lack of proper design, I may not permit it. However, if the contractor is dilligent in his effort to place the disconnect at a point that meets those three factors above, it will be approved every time.
 
Re: OKAY...LETS STIR THE POST SOME

The point closest has always been a problem. Suppose you have a run under a slab to the center of the building and it then turned up to the 100 ampere panelboard. Are you going to set the small panelboard on the floor or mount it at eye level? How much exposed conduit do you have under the panelbord? Assuming five ft, why not permit that much to be used as the maximum for any location?

How about a straight up and down service located on the outside basement wall? Will you permit me to have some exposed conduit or SE cable there without an outside disconnecting means? Again, how much is exposed and how dangerous is the installation?

It is easy to see how the rule has been bent over the years. However, it is also recognized that any deviation is exposing the occupant to danger. The question is how much danger is acceptable to the AHJ and the EC? The problem with my last question is that the occupant has no say in or the knowledge of the danger being chosen for him. :D
 
Re: OKAY...LETS STIR THE POST SOME

how do you figure that "any deviation" exposes the occupant to danger?

there is an existing danger in just having electrical service at all. how is 5 feet of SE cable inside the building any more dangerous then 4 feet or less dangerous than 6 feet, especially if it is not exposed?
 
Re: OKAY...LETS STIR THE POST SOME

If you apply the words as written, the disconnect must be at the point where the conductors enter the building. There is no allowance in the code wording for even 1' of service conductor inside the building. Now the question becomes where does "inside" start? Is the interior of the wall inside of the building? If so, all service disconnects must be outside.
Don
 
Re: OKAY...LETS STIR THE POST SOME

I posted the following in another thread. I'll repeat my comment here, because it remains my answer to this question.
Originally posted by charlie b The event (i.e., the hazard) that we are trying to prevent is accidental damage to the service conductors at a point upstream of the overcurrent protection. There would be no protective action to terminate a fault located at that portion of the circuit. The lower we can make the probability of that event, the safer we can make the installation. In order to reduce the probability of something striking the service conductors, we limit the distance that they are allow to run. That distance is measured from the point at which they enter the building to the point at which the overcurrent protection device is located. It is not reasonable to insist that that distance be zero. The writers of the NEC chose not to set a maximum distance, though some jurisdictions have made that choice. For example, in Washington State, the limit is 15 feet.
Click to expand...
And now to Pierre's Other question:
Originally posted by pierre:
What is the real reason that this disconnect is being installed?
Click to expand...
I understood that the disconnect existed to allow the fire department an opportunity to enter the building and safely spray water all over the place, without risk of electrical shock. I may have been misinformed about this reason, but it is the only one I can offer.
 
Re: OKAY...LETS STIR THE POST SOME

"reasonable" or "unreasonable" is irrelevant. This is a topic which points out that even thumpers of the NEC, the ones that stand in front of the class and bang the book several times on the desk, dias, or pulpit also claim the right to re-interpret the NEC for local conditions. As Don has pointed out, there is no provision for entering the building at all, before reaching a disconnect. Claiming that it is unreasonable to require what the code says does not alter what is written.

I always thought that i was still outside the building while running a rigid mast inside the stud space of an external wall, from weatherhead to meter to disconnect. Someone pointed out my blindness to knock me off the soap box on this one. I think it is interesting that there are so many twists to the re-interpreting of this code section.

paul :)
 
Re: OKAY...LETS STIR THE POST SOME

Paul, how do you feel about this installation?

electrical2.jpg


I took this picture while visiting California about 5-6 years ago. For those who might be confused, this is the back of an "all-in-one service" that is common out west. This is mounted on the garage wall, with the meter, main breaker and circuit breakers all facing outside. There are hundreds of thousands of these all across the West.

We've been down this road before. If what you say is true, then literally millions of services all across the country are in violation, from New England to San Diego.

[ October 14, 2005, 03:44 PM: Message edited by: peter d ]
 
Re: OKAY...LETS STIR THE POST SOME

Originally posted by don_resqcapt19:
Now the question becomes where does "inside" start? Is the interior of the wall inside of the building? If so, all service disconnects must be outside.
Don
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We would have to be some what consistant with 220.3(A) wouldn't we?

If the floor area is computed from the outside of the structure, then all the space within the outside finish would be interior.

Roger
 
Re: OKAY...LETS STIR THE POST SOME

Someone show me a history of deaths, injuries, fires, or any other acidents occuring from disconnecting means installed some point after the nearest point of entry. I'll save you the time, there aren't any.
 
Re: OKAY...LETS STIR THE POST SOME

Originally posted by pierre:
If I can come into the building any of those distances, why not further? Why not 25', why not 50'?
Click to expand...
I always figured the longer the run of cable the more likely it will sustain damage.
 
Re: OKAY...LETS STIR THE POST SOME

The NEC is not a design manual. It is up to each governing body to accept or modify the language of NEC before it is enforcable.

Wisconsin has modified the language of NEC 230.70 to give an unprotected distance of 8ft maximum. They further define the entrance to a building as passing "through the outer surface of the building."

What Wisconsin has done has no bearing on any other jurisdiction.
 
Re: OKAY...LETS STIR THE POST SOME

Originally posted by roger:
Originally posted by don_resqcapt19:
Now the question becomes where does "inside" start? Is the interior of the wall inside of the building? If so, all service disconnects must be outside.
Don
Click to expand...
We would have to be some what consistant with 220.3(A) wouldn't we?

If the floor area is computed from the outside of the structure, then all the space within the outside finish would be interior.

Roger
Click to expand...
I agree with Roger on this statement.
 
Re: OKAY...LETS STIR THE POST SOME

We are supposed to read the code and use the words to the best of our ability to enforce/install to the measure of the intent and safety.

Like Don, I do not see where this section permits the service disconnect anywhere in the building, past the point of entry.

Lets forget safety and look at the words.

"outside ofa building or structure or inside nearest the point of entrance..."


MY read on this is not 5', 8', or whatever, but nearest the POE.
But like some other code requirements, the requirement is not specific enough to really say so, as "nearest" is too ambiguous.

[ October 14, 2005, 06:02 PM: Message edited by: pierre ]
 
Re: OKAY...LETS STIR THE POST SOME

Originally posted by pierre:. . . "nearest" is too ambiguous.
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That is the core heart of the problem.

I believe that it would not be a violation of the rules of the English Language, nor even much of a stretch, to interpret that line by saying, "Because of these interferences, the nearest that I can mount an enclosure to that wall is 29 feet away, against this other wall, so I'll put the disconnect there." I also believe that some jurisdictions (WA State is one, as I said earlier) set a specific distance limit in order to prevent anyone from interpreting the rule in this manner, and running the conductors as long as they wish.

I've said this before, but I'll say it again in a different way:

(1) I believe that the word "nearest" does not require me to place the disconnect on the inside wall, let alone force me to put it outside,

and

(2) Nobody can tell me that I am using the word "nearest" in a way that is in conflict with its definition. The word has several definitions, and the one I am using is among them.

So there. :cool:
 
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