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#91757 - 02/03/05 11:58 AM service diconnect?  
Reel-Break  Offline
Member
Joined: Apr 2002
Posts: 178
nc
Hey I have question.What determines when a disconnect is needed. Residential.Here`s what I mean back to back I don`t need one guy here says if I leave meter can and drop under wall to crawl space and back up even if meter is back to back I must have a disconnect. Or if I go over head and drop back into the panel I must have a dico.Is there a section where his interpitation is wrong? Please send some artical #`s Hope this question makes sense.Some poeple say 10ft of cable but have`nt seen it in the book. Thanks for some insight on this.


2017 / 2014 NEC & Related Books and Study Guides

#91758 - 02/03/05 01:01 PM Re: service diconnect?  
cpal  Offline
Member
Joined: May 2004
Posts: 162
Cohasset MA
I'm not sure I follow the question, but every source that supplies a building or structure will Generally require means to completely disconnect all those conductors which provide supply including the grounded conductor.

The NEC is rather silent in regard to the distance travelled with in the building before a disconnect is installed. (not to say you should run extensive lengths). I believe the disconnect should be installed closest to the point of entry at the first readily accessible location.

Local Codes may have a thing or two to say on this matter.


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.


#91759 - 02/03/05 01:07 PM Re: service diconnect?  
mustangelectric  Offline
Member
Joined: Feb 2004
Posts: 494
Bentonville, AR
Hi,
Are you using raceway or cable?

SE should be protected from the meterbase to the first ocpd if it is subject to physical damage..

Say i run a se cable from the meterbase to the first ocpd, that se cable needs a raceway for PROTECTION.

If you run a SE cable from a meterbase to the first ocpd you really need a disconnect outside. There is NO FUSE between your first ocpd and the transformer! You will need a 4 conductor cable from the first ocpd to your next panel.

Hope that helps.

Regards

greg



[This message has been edited by mustangelectric (edited 02-03-2005).]


Electricity has no respect for ignorance!

#91760 - 02/03/05 01:18 PM Re: service diconnect?  
mustangelectric  Offline
Member
Joined: Feb 2004
Posts: 494
Bentonville, AR
Hi,
Another thing...

You said: "Hey I have question.What determines when a disconnect is needed. Residential.Here`s what I mean back to back I don`t need one"...when do you not need a disconnect on a service?

You said: "guy here says if I leave meter can and drop under wall to crawl space and back up even if meter is back to back I must have a disconnect"...Not if it is in a RACEWAY.

Say I have a meterbase on the wall...overhead drop...then I need to run a pipe down the wall to a panel..I do not need a disconnect outside to do this.

BACK to BACK does not matter.

It is done ALL THE TIME ALL OVER THE WORLD!

Regards

Greg

[This message has been edited by mustangelectric (edited 02-03-2005).]


Electricity has no respect for ignorance!

#91761 - 02/03/05 01:24 PM Re: service diconnect?  
mustangelectric  Offline
Member
Joined: Feb 2004
Posts: 494
Bentonville, AR
Hi,

Sorry for hogging this thread!

CPAL you said: "every source that supplies a building or structure will Generally require means to completely disconnect all those conductors which provide supply including the grounded conductor"

How so?

Are you saying switched neutral?

Regards

Greg

[This message has been edited by mustangelectric (edited 02-03-2005).]


Electricity has no respect for ignorance!

#91762 - 02/03/05 02:28 PM Re: service diconnect?  
Reel-Break  Offline
Member
Joined: Apr 2002
Posts: 178
nc
Ok here goes another try..I put a 200a meter on the house panel is back to back.No disco needed( come out of the meter can drill over 1 stud enter panel top or bottom.)Now I`m being told say for example I the meter can is mounted say on the crawl space and the se cable enters the crawl space and then goes up thrugh floor to panel I`ll need a disco because I breached the wall even if I`m back to back. Lets say I have meter can and run over 5 studs is a dico required? Where`s it in code is my question. Maybe I`m not explaining it good.


#91763 - 02/03/05 04:15 PM Re: service diconnect?  
markp  Offline
Member
Joined: Apr 2004
Posts: 60
Kent, WA, USA
The code is silent on the specific length, but someone did point out a relevant section. This issue is how far can a service conductor come into a building before it must terminate in the building disconnect. Here in Washington, it is 15 feet. Some places it 10' or 5'. You'll have to ask your inspector or read any local codes to see how far a service conductor can come into a building before being terminated.

And as someone else mentioned, the location of the meter is not relevant. You can run 50 feet of conduit on the outside wall past the meter before entering the structure. But once you poke a hole and come inside the house, there is a limit on service conductor length.


Mark
Kent, WA

#91764 - 02/03/05 04:22 PM Re: service diconnect?  
cpal  Offline
Member
Joined: May 2004
Posts: 162
Cohasset MA
The Code recognizes the termination of the grounded circuit conductor under a pressure lug as a means of disconnect for feeder and services. or a removeable section of bus bar!!

230.75 Disconnection of Grounded Conductor.
Where the service disconnecting means does not disconnect the grounded conductor from the premises wiring, other means shall be provided for this purpose in the service equipment. A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose. In a multisection switchboard, disconnects for the grounded conductor shall be permitted to be in any section of the switchboard, provided any such switchboard section is marked.


225.38 Disconnect Construction.
Disconnecting means shall meet the requirements of 225.38(A) through (D).
Exception: For garages and outbuildings on residential property, snap switches or sets of 3-way or 4-way snap switches shall be permitted as the disconnecting means.
(A) Manually or Power Operable. The disconnecting means shall consist of either (1) a manually operable switch or a circuit breaker equipped with a handle or other suitable operating means or (2) a power-operable switch or circuit breaker, provided the switch or circuit breaker can be opened by hand in the event of a power failure.
(B) Simultaneous Opening of Poles. Each building or structure disconnecting means shall simultaneously disconnect all ungrounded supply conductors that it controls from the building or structure wiring system.
(C) Disconnection of Grounded Conductor. Where the building or structure disconnecting means does not disconnect the grounded conductor from the grounded conductors in the building or structure wiring, other means shall be provided for this purpose at the location of disconnecting means. A terminal or bus to which all grounded conductors can be attached by means of pressure connectors shall be permitted for this purpose.
In a multisection switchboard, disconnects for the grounded conductor shall be permitted to be in any of the switchboard, provided any such switchboard is marked.

Reel Break, read 230.70 there is no simple answer that I am aware of.


Charlie

[This message has been edited by cpal (edited 02-03-2005).]


#91765 - 02/03/05 05:16 PM Re: service diconnect?  
winnie  Offline
Member
Joined: Sep 2003
Posts: 649
boston, ma
Reel Break,

Your question is a bit confusing, because you ask 'What determines when a disconnect is needed'. The answer is _always_. You always need to have a way to shut off power to a building. The rest of your question suggests that what you are really asking is when can the main breaker in the 'main' circuit breaker panel be used as the disconnect, and when does a separate disconnect need to be placed near the meter.

The code references supplied by others go to answer that question. If you think in terms of always having a main disconnect, and asking how far the conductors prior to the disconnect can extend into the structure, the answers will make sense.

-Jon


#91766 - 02/03/05 05:55 PM Re: service diconnect?  
Electricmanscott  Offline
Member
Joined: Jan 2002
Posts: 1,457
Holden, MA USA
Quote
Say i run a se cable from the meterbase to the first ocpd, that se cable needs a raceway for PROTECTION.

If you run a SE cable from a meterbase to the first ocpd you really need a disconnect outside. There is NO FUSE between your first ocpd and the transformer! You will need a 4 conductor cable from the first ocpd to your next panel.


This not true if you are using the NEC. The NEC does not specify which wiring methods need a diconnect and which do not. You can use SE cable down the side of the house, into the meter, out of the meter, into the panel with a main breaker in the basement as long as it is immediately upon the cable entering the building and is not subject to physical damage.


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