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#163546 - 05/10/07 04:05 AM Cut Neutral
electricianjeff Offline
Junior Member

Registered: 03/17/07
Posts: 8
Loc: Southern Illinois
I did a 100 amp. redo yesterday in a city I don't work in often. It was an older home than had been added on to a bunch of times. The panel was 30' from the service entrance so I had to run new wire and pipe through a crawlspace, add an outside disconnect, isolate grounds and neutrals downstream, etc.

Question #1: When I spoke to the inspector about how I was going to fix it he said I had to be in rigid from "weatherhead to old panel. I always thought that once I entered the structure I could jump to thinwall inside. Have done it before in basements with no problem from inspectors. Am I mistaken on this?

Question #2: I ran the neutral through the meter socket and terminated it in the disconnect. From there I ran the neutral into the inside panel. The inspector wanted the neutral ran continous from weather head to inside panel. He said "I'm not going to red tag you this time, but next time do it right!" I took the position "in a nice way" that the disconnect is now the main panel and the neutral is always cut at the main panel and then feed to the subpanels. I don't see where the fact that the main panel is now on the outside of the house would make any difference?

I'm always wanting to learn something and I havn't really done many outside disconnects, I think this was my third one in 5 or so years. I would appreciate any help offered as to the proper install given these circumstances.

electricianjeff

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#163548 - 05/10/07 07:24 AM Re: Cut Neutral [Re: electricianjeff]
sabrown Offline
Member

Registered: 12/12/02
Posts: 297
Loc: Ogden, Utah, USA
Without a local ordinance requiring what the inspector requested, I do not see a problem with the insulation as I understand it.

The exterior disconnect does become the main service disconnect and as long as the isolation mentioned above occurs and new grounding electrode conductor system is installed to the new main, it sounds correct.

Shane

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#163619 - 05/12/07 10:59 AM Re: Cut Neutral [Re: sabrown]
Zapped Offline
Member

Registered: 10/01/02
Posts: 481
Loc: Huntington Beach, CA, USA
Are you bonding your ground rod or ufer at the disconnect, and then running seperate ground and neutrals to your subs? Or are you grounding at your panel? This makes a difference...

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#163623 - 05/12/07 12:14 PM Re: Cut Neutral [Re: electricianjeff]
frenchelectrican Offline

Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
 Originally Posted By: electricianjeff
I did a 100 amp. redo yesterday in a city I don't work in often. It was an older home than had been added on to a bunch of times. The panel was 30' from the service entrance so I had to run new wire and pipe through a crawlspace, add an outside disconnect, isolate grounds and neutrals downstream, etc.

Question #1: When I spoke to the inspector about how I was going to fix it he said I had to be in rigid from "weatherhead to old panel. I always thought that once I entered the structure I could jump to thinwall inside. Have done it before in basements with no problem from inspectors. Am I mistaken on this?

A: it depending on the local codes some will allow this kind of pratice [for myself i just run the same all the way to the main breaker box ]

Question #2: I ran the neutral through the meter socket and terminated it in the disconnect. From there I ran the neutral into the inside panel. The inspector wanted the neutral ran continous from weather head to inside panel. He said "I'm not going to red tag you this time, but next time do it right!" I took the position "in a nice way" that the disconnect is now the main panel and the neutral is always cut at the main panel and then feed to the subpanels. I don't see where the fact that the main panel is now on the outside of the house would make any difference?


A; Most Metering device do split the netural with common lug design but again the local codes will trump it.

The other issue it will make the diffrence where you land the grounding wire to bond it they have two maybe three diffrent codes to follow up on this as well.



I'm always wanting to learn something and I havn't really done many outside disconnects, I think this was my third one in 5 or so years. I would appreciate any help offered as to the proper install given these circumstances.

electricianjeff
_________________________
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


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#163639 - 05/13/07 07:33 AM Re: Cut Neutral [Re: frenchelectrican]
Alan Nadon Offline
Member

Registered: 03/10/05
Posts: 398
Loc: Elkhart, IN. USA
In my opinion, the grounded conductor needs to be bonded at all points ahead of the service disconnect. This allows a fault to take the shortest path back to the source of power.
If I follow your description a fault in the meter socket would mean the conduit and neutral/ grounded conductor would take the fault into the building to the main panel bond before allowing the fault to go to the transformer or souce. A fire waiting to happen.
Alan--
_________________________
Alan--
If it was easy, anyone could do it.

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#163641 - 05/13/07 09:19 AM Re: Cut Neutral [Re: electricianjeff]
e57 Offline
Member

Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
 Originally Posted By: electricianjeff

Question #2: I ran the neutral through the meter socket and terminated it in the disconnect. From there I ran the neutral into the inside panel.


No bond connection of the neutral in the meter pan? Most pans are lay-in lug types mounted directly to the can, so you don't have to cut the neutral, just strip it and terminate the neutral and have it go straight through, but that is not nessesary, unless there is a local code for that requires it to be continuous. But the neutral does need to be landed there as a main bonding jumper, as well as in the main disconnect.
_________________________
Mark Heller
"Well - I oughta....." -Jackie Gleason

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#163656 - 05/13/07 07:18 PM Re: Cut Neutral [Re: electricianjeff]
BGaquin Offline
Junior Member

Registered: 05/08/03
Posts: 16
Loc: Sterling, VA
The service disconnect (with OCP) is just that the service disconnect. The neutral/grounded conductor is bonded to ground in the service disconnect. Everything downstream is a subpanel and the neutral/grounded conductor is isolated from the EGC.

If the inspector said anything different from this WELL HE IS WRONG, at least per the NEC and logic, maybe he has his own CODE.

From the meter to the first OCP (service disconnect), did you run SER or conduit?

 Quote:
In my opinion, the grounded conductor needs to be bonded at all points ahead of the service disconnect. This allows a fault to take the shortest path back to the source of power.
If I follow your description a fault in the meter socket would mean the conduit and neutral/ grounded conductor would take the fault into the building to the main panel bond before allowing the fault to go to the transformer or source. A fire waiting to happen.


AHEAD of the service disconnect? You mean in the meter?

AND WHY DO YOU SAY THIS?....

An isolated Neutral in the meter can (if an EGC is installed) would make little or difference during a fault.

A fault on two paths is still going to return to the source. If you run Rigid with 3 conductors to the service disconnect, from the meter back box and the neutral is bonded to the back box (typical utility installation), the fault path (and normal neutral current) will be on the neutral/grounded conductor and the EDG (service conduit).

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#163661 - 05/14/07 01:19 AM Re: Cut Neutral [Re: BGaquin]
e57 Offline
Member

Registered: 05/27/03
Posts: 2837
Loc: S.F.,CA USA
 Originally Posted By: BGaquin

If the inspector said anything different from this WELL HE IS WRONG, at least per the NEC and logic, maybe he has his own CODE.

From the meter to the first OCP (service disconnect), did you run SER or conduit?

~

An isolated Neutral in the meter can (if an EGC is installed) would make little or difference during a fault.


I think the point Alan was making about bringing the fault path inside the building is a valid one.

I would not be able to not bond the neutral in the meter. Our inspectors here would have a hayday trying to make me figure out if the conduit corrossion resistant and its connections met the cross-sectioal area to equal or exceed 250.66, or if the impedance of the connections was sufficient.

Meters aren't cover in the NEC, the enclosures are. It is not the only method, but one of them. (The easiest one) Yet the conduit method is not one of the items listed in 250.28(A)IMO. While you can not have a MBJ in a sub panel, and you do need it in the main disco, you can also have one in the meter section. Often it is hard not to, as most neutral terminations are mounted on the can itself. Sounds like the OP skipped this connection having one MBJ inside the building????

 Quote:
250.92(B) Method of Bonding at the Service. Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:
(1) Bonding equipment to the grounded service conductor in a manner provided in 250.8
(2) Connections utilizing threaded couplings or threaded bosses on enclosures where made up wrenchtight
(3) Threadless couplings and connectors where made up tight for metal raceways and metal-clad cables
(4) Other approved devices, such as bonding-type locknuts and bushings


 Quote:
250.28(A) Material. Main bonding jumpers shall be of copper or other corrosion-resistant material. A main bonding jumper shall be a wire, bus, screw, or similar suitable conductor.


"Suitable" would be subject to debate by the AHJ...
_________________________
Mark Heller
"Well - I oughta....." -Jackie Gleason

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#163666 - 05/14/07 04:19 AM Re: Cut Neutral [Re: electricianjeff]
BGaquin Offline
Junior Member

Registered: 05/08/03
Posts: 16
Loc: Sterling, VA
The statement was AHEAD of the meter, this means UPSTREAM of the meter between the meter and the utility transformer?

How would a fault in the meter can result in fault current in the building (even with improper grounding)? A fault in the meter can can result in a impulse in the downstream electrical distribution system, and an impulse of significant magitude MIGHT cause a fire, or a sustained fault in the meter can (OCPs on the utility side do not open) may lead to a fire.

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#163670 - 05/14/07 08:36 AM Re: Cut Neutral [Re: BGaquin]
Alan Nadon Offline
Member

Registered: 03/10/05
Posts: 398
Loc: Elkhart, IN. USA
The possible fire:
Line side conductor faults to meter enclosure. Fault energizes conduit to panel inside building where main bonding jumper connect to GEC and grounded conductor.
GEC rod, water pipe, building steel have high enough resistance / impedence to not open over current devices at source of power.
Conduit from meter socket to main bonding jumper gets red hot. Source of heat is inside the building.
Bonding the meter socket to the grounded conductor would keep the fault from that point back to the source and outside the building.
It will not prevent a fire but, would keep it from being inside the building
Alan--
_________________________
Alan--
If it was easy, anyone could do it.

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