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service diconnect?

Posted By: Reel-Break

service diconnect? - 02/03/05 03:58 PM

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.
Posted By: cpal

Re: service diconnect? - 02/03/05 05:01 PM

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.
Posted By: mustangelectric

Re: service diconnect? - 02/03/05 05:07 PM

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).]
Posted By: mustangelectric

Re: service diconnect? - 02/03/05 05:18 PM

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).]
Posted By: mustangelectric

Re: service diconnect? - 02/03/05 05:24 PM

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).]
Posted By: Reel-Break

Re: service diconnect? - 02/03/05 06:28 PM

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.
Posted By: markp

Re: service diconnect? - 02/03/05 08:15 PM

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.
Posted By: cpal

Re: service diconnect? - 02/03/05 08:22 PM

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).]
Posted By: winnie

Re: service diconnect? - 02/03/05 09:16 PM

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
Posted By: Electricmanscott

Re: service diconnect? - 02/03/05 09:55 PM

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.
Posted By: mustangelectric

Re: service diconnect? - 02/04/05 01:25 PM

Hi,
Electricman-

You said: "is not subject to physical damage"

This is my point.

I am aware that some places it is acceptable to run a SE cable for the se conductors and feeder.

I also am not sure if it is code or not but it is the way to go. It may be that I have to ask an inspector for his interpretation. I do not know of ANY inspector that will allow a SE CABLE to extend from the meter base to the first ocpd without PROTECTION.

You can not do it anywhere I have ever worked.

My point was that the cable between the meter base and the first OCPD HAS NO PROTECTION.

If someone got into that cable they would have a serious problem.

If the cable has a breaker ahead of it I see no problem.

Without it...it’s dangerous.

Thanks for the comments.

Regards

Greg

Edited for content


[This message has been edited by mustangelectric (edited 02-04-2005).]
Posted By: Reel-Break

Re: service diconnect? - 02/04/05 01:42 PM

Hey Scott thats what has me confused.I`m working with an electrician now who says if I leave the meter can even if it`s 5 ft if I go outside the wall the meter can is mounted I need a dico.Just want to clear this up. I guess based on post maybe it will vary inspector to inspector I personally have a hard time with that.I`m the grunt pulling wire and.... do things this way here its fine drive 20m miles away and you`re a dumb ass?? sorry but I`m working on getting the code down now.
Posted By: mustangelectric

Re: service diconnect? - 02/04/05 02:01 PM

Hi,
Cpal- Thanks for the code reference. I was not sure what the heck you were saying!

I say that when dealing with the service entrance conductors and distance inside a building, that this should NOT MATTER IF there is a ocpd at the meter. And if correct I do not beleive it does restrict the length.

The Main should be outside in my own opinion just so that it is accessible to the fire dept. etc.

My suggestion is to go buy a CSED or a combination meter and disconnect. If you use this you will never have a problem.

It may even be cheaper because you do not need a MBO panel you can use a MLO panel after that.

I worry that a se cable that is ran along the face of a floor joist or that is pulled through a stud wall IS subject to physical damage if you can drive a nail, screw or saw through it.

Take a sawsall and cut through a wall with a 200A se cable running through it with no ocpd and you could have a lethal situation.

Just my 2 cents.

A little extra work can add a whole new dimension to the safety of your installations.

Regards

Greg



[This message has been edited by mustangelectric (edited 02-04-2005).]
Posted By: cpal

Re: service diconnect? - 02/04/05 02:46 PM

Mustang
I applaud your workmanship and sense of responsibility.
More is generally better, but the NEC is a minimum standard and I do not believe that there is a minimum distance that unprotected conductors can transit (concealed or exposed) at a premises, cable or raceway. Obviously individual wiring methods will influence conditions of installation but they must be assessed for each case.

That being said it is a wise electrician that pays attention to the pucker factor.

Additionally local codes may influence such installations. In my jurisdiction the inspectors are limited in their interpretation of the Code. Local Codes although implied essentially do not exist.

We have a State board that adopts the NEC with amendments and local inspectors are sworn to follow these documents to best of their ability.


Keep up the good work

Charlie
Posted By: Electricmanscott

Re: service diconnect? - 02/04/05 09:53 PM

Gregg, the se cable before the meter has no ocp either. Why does it matter if it is before or after the meter? The danger is equal and I do agree there is the potential for danger. From your replies I assume you have local codes that overide the NEC. Many houses around here have se fed out from the meter going into the basement where the service panel is located. It is usually a judgment call as to how far you can go with the unfused se. I saw one today that is about 15 feet. Certainly not "Nearest the point of entry of service conductors" as the NEC requires.
Posted By: cpal

Re: service diconnect? - 02/04/05 10:12 PM

Un fused conductors present a problem, I believe that is why the language in 230.70 suggests that the service equipment be located "at a readily accessible location either outside of a building or structure or inside nearest the point of entrance of the service conductors".
230.50 Protection of Open Conductors and Cables Against Damage — States that Service-entrance conductors installed above ground shall be protected against physical damage.

Who determines if the cable is subject to physical damage??

Most installers would say it is obvious.
Posted By: mustangelectric

Re: service diconnect? - 02/04/05 10:45 PM

Hi,
I went to college in Maine and that is where I first encountered a jurisdiction that allows this. I later found out that it is done a lot in new england and some in kentucky.

Most other states and places that were not states would not allow this.

I see it all the time and yes it is permitted by the code BUT that depends on who you ask I guess.

I have seen the old and the new SE Cable setups and some of the older ones are pretty scary the way some of them terminate from the cable and weatherhead etc.

It is a cheap way to do it that is for sure!

I have never tried it but it looks like a quick install.

That is why I think that the code needs to change and to require the FIRST OCPD to be mounted adjacent to the METERBASE. I have seen some meters at the transformer so I do not know how well that would work out but it would settle a lot of arguments! Besides how many closets, cabinets, garages and god only knows what other locations meters and panels seem to end up. I saw one the other day that was a 42 circuit sq-d 200A main b panel full to the gills INSIDE of a ENTERTAINMENT CENTER. I had to lay on my stomach and lean in to get the cover off!

Another interesting thing I saw..someone had used the meterbase as a raceway and ran some 2/0 back out through the nipple to the meterbase and out the bottom of the meterbase to a new pool!

The poco will nail them the next time they read it...maybe!

Shoot even a 4 conductor 200 or 300A feeder with a breaker ahead of it is scary enough!

I do not want to find out how long it would take for the breaker to trip if I accidentally got into it!

I think when the code says "PHYSICAL PROTECTION" a se cabl with no protection between the xfmr and the first ocpd is exactly what they were talking about!

Very interesting topic though!

Regards

Greg
Posted By: iwire

Re: service diconnect? - 02/04/05 11:02 PM

Greg in order to get the code changed you would need to show a problem with the code how it is today.

Having grown up in an area that uses a lot of SE I have not seen any problems with it.

It's great to go beyond code at times. [Linked Image]

My own house has an SE service, I had bent up some RMC and started to install that, I did not like how it looked. I trashed the RMC and got copper SE.

Oh and my service disconnect is in the basement, about 5' from the point of entrance.

Bob
Posted By: mustangelectric

Re: service diconnect? - 02/05/05 12:28 AM

Hi,
i ahve seen the meterbase be on one end of a 2 story house with a basement and have the disconnect in the basement on the other end!

It varies a lot!

I cant name a single problem that I am aware of due to using the SE cable.

I love the stuff myself!

I have seen PVC and used it for short risers. I prefer EMT or IMC.

Regards

Greg

[This message has been edited by mustangelectric (edited 02-04-2005).]
Posted By: Electricmanscott

Re: service diconnect? - 02/05/05 02:53 AM

Greg I don't think the code says "physical peotection". It says "Protection from physical damage". Totaly different. One means you would not be able to run se it by itself. The other means it has to be protected from physical damage. That is where the interpretation comes in. I see no basis for a code change on this one.
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