Grouping disconnects

[ivsenroute]

OK Picture This (sorry no pics):

A slab on grade duplex or twin or two-family residence, whichever you want to call set up with an upper and lower unit.

There is an overhead single service drop, lets say 200A that comes down to a 2 gang meter base. The EC wants to run the service entrance cable on the outside of the house to the 2nd floor where a main panel will be located at the nearest point of entry of course. He will do the same for the 1st floor.

This way, they are both main panels and he does not have to buy a disco and run 4 wire to the 2nd floor.

Is this possible with a single service drop considering you would be violating 230.72?

 

[mpd]

yes, per 230.40 exception #1

 

[ivsenroute]

yes, per 230.40 exception #1

That was my initial thought too, but no, that only allows 1 set per service and is a way to get around 230.72. However, as I states, there is only 1 service drop to the meter base so 230.40 exception #1 would not apply.

 

[augie47]

I don't care for it, but I agree with mpd. Multi-occupancy building, one service drop with a set of service entrance condcutors for each occupancy. The handbook shows something similar with 230.9 except it's a service lateral.
Locally (1) of our POCO won;'t accept it but another will.

 

[mpd]

IMO, 230.40 exception #1, permits 1 set of service entrance conductors to be run to each occupancy, and 230.71 permits this, i could have 6 disconnects in each unit grouped in the same location

 

[jwjrw]

That was my initial thought too, but no, that only allows 1 set per service and is a way to get around 230.72. However, as I states, there is only 1 service drop to the meter base so 230.40 exception #1 would not apply.[/QUOT
The meter for the top floor being in the same can and leaving there unfused for god knows how many feet before entering the top unit panel is a violation correct? Maybe I'm not thinking clearly help me out.

 

[ivsenroute]

jwjrw,

As long as the "unfused" service cable is outside of the structure, there is no limit on distance before it enters the structure.

 

[jwjrw]

jwjrw,

As long as the "unfused" service cable is outside of the structure, there is no limit on distance before it enters the structure.

I know you are right whats the number please. And I know its up to most ahj to how far into the house it can come but whats that section also?

 

[ivsenroute]

Maybe we have to look at definitions. Here is the code text to help with this one.

230.40 Number of Service-Entrance Conductor Sets.
Each service drop or lateral shall supply only one set of service-entrance conductors.
Exception No. 1: A building with more than one occupancy shall be permitted to have one set of service-entrance conductors for each service, as defined in 230.2, run to each occupancy or group of occupancies.

230.72 Grouping of Disconnects.
(A) General. The two to six disconnects as permitted in 230.71 shall be grouped. Each disconnect shall be marked to indicate the load served.

230.71 Maximum Number of Disconnects.
(A) General. The service disconnecting means for each service permitted by 230.2, or for each set of service-entrance conductors permitted by 230.40, Exception No. 1, 3, 4, or 5, shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard. There shall be not more than six sets of disconnects per service grouped in any one location.
For the purpose of this section, disconnecting means installed as part of listed equipment and used solely for the following shall not be considered a service disconnecting means:
(1) Power monitoring equipment
(2) Surge-protective device(s)
(3) Control circuit of the ground-fault protection system
(4) Power-operable service disconnecting means

 

[mpd]

Maybe we have to look at definitions. Here is the code text to help with this one.

IMO, those sections support my interpretation

 

[don_resqcapt19]

IMO, those sections support my interpretation

There is no question that they do. Each occupancy is permitted to have a set of service entrance conductors and each set of service entrance conductors is permitted to have up to six means of disconnect.

 

[ivsenroute]

Initially as I stated, I did go right to exeption #1 for 230.40 but I believe that only allows us to supply several sets of service entrance conductors but it still not listed as an exception for 230.72 which is about grouping disconnects permitted by 230.71 including exception 1 of 230.40.

I was in your camp on this one until someone else brought this to my attention and explained it.

Even when I go to different sources for an explanation of 230.40 exception 1, the diagrams/figures show different locations for disconnects only by having separate OH or lateral drops.

I am having a difficult time convincing myself to go back to the way I originally interpreted this.

 

[jaylectricity]

Do the meters count as a disconnect?

 

[George Stolz]

Do the meters count as a disconnect?

No, they do not.

 

[mpd]

Initially as I stated, I did go right to exeption #1 for 230.40 but I believe that only allows us to supply several sets of service entrance conductors but it still not listed as an exception for 230.72 which is about grouping disconnects permitted by 230.71 including exception 1 of 230.40.

I was in your camp on this one until someone else brought this to my attention and explained it.

Even when I go to different sources for an explanation of 230.40 exception 1, the diagrams/figures show different locations for disconnects only by having separate OH or lateral drops.

I am having a difficult time convincing myself to go back to the way I originally interpreted this.

take a look at the commentary in the NEC handbook for section 230.71, and per that section i can have 6 disconnnects grouped at any one location, it does not say they all must be at the same location, 230.72 would only require my disconnects in that occupancy to be grouped

 

[jaylectricity]

No, they do not.

Then I say you have to use a two gang meter socket with disconnects and send 4 wires to the panels in each unit.

 

[mpd]

Do the meters count as a disconnect?

look at 230.66 (2008 NEC)

 

[jaylectricity]

look at 230.66 (2008 NEC)

Ah thanks. It never comes up in my jobs, so I didn't know there was a code for it.

 

[don_resqcapt19]

First I think that Exception #1 to 230.40 very clearly permits a single service drop or service lateral to supply multiple sets of service entrance conductors.
Second it is clear that 230.71 permits up to six means of disconnect for each set of service entrance conductors.
The third step is not as clear, but to me, it does only requires the grouping of service disconnects that are for the same set of service entrance conductors. There is no requirement that the service disconnects for one set of service entrance conductors be grouped with those for another.
Take a look at the following panel statement from proposal 4-44 for the 2008 code.

Panel Statement: This particular exception has been in the NEC since at
least the 1946 NEC where Section 1807 permitted, by special permission,
more than one set of service drop in a multi-occupancy building where there
was no available space for service equipment accessible to all occupants.
This exception permitted the occupant to have access to their own service
disconnecting means. Section 1837 required a multiple occupancy building
having individual occupancies above the second floor to have the service
equipment grouped in a common accessible location and to consist of not
more than six switches or circuit breakers. However, any multiple occupancy
building that did not have any individual occupancy above the second floor
could have the service conductors run to each occupancy and have up to six
switches or circuit breakers at that location.
Since this rule has existed since the early 1940s without a major change to
the intent, there does not seem to be a compelling reason to change this section
of the Code and there was no technical substantiation given in the proposal to
provide a reason to delete this rule. The submitter did not provide any specific
examples of problems that have occurred where service entrance conductors
have been installed in accordance with the current permissive requirements in
this section.
Exception 1 to 230.40 is a necessary and commonly used allowance for
supplying power in multiple occupancy buildings. The building is still only
permitted to have one service riser or lateral that would allow the power to be
removed from all occupancies when necessary by the disconnection of the riser
or lateral conductors.

 

[ivsenroute]

Yes, there it is. Exhibit 230.25 of the 2002 Handbook. It shows a single what appears to be a utility owned transformer with 2 separate laterals. Each lateral feeds a disconnect so 230.72 does not apply since there is only 1 service cable per service lateral/drop.

It is my belief that if they took the same exhibit and only showed 1 laterall coming to a 2 gang meter, the discos would have to be grouped per 230.72.

230.72 simply offers no exception. The service conductors are from the point of service to the disconnect.