Is this considered a Sub-Panel or Not?

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nsmaby

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Hello,

Looking for some help here. I've got 200 amp service coming into a Main single 200 amp breaker box (exterior). Immediately next to this box, inside the garage is a main lug 200 amp load center.

What is the correct way to connect grounds and neutrals for this setup? Should this be treated as a subpanel setup, where the neutral and ground bus's should be separate? or since they are essentially at the same location (with no other circuits in between) can I install one service ground?

Thanks for any help.

Niels
 
physis

physis

Senior Member
Re: Is this considered a Sub-Panel or Not?

It is a sub panel.

Look at Article 100 for definitions of service "equipment" "disconnect" and "conductors".

Unless Roger disagrees :D
 
roger

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Re: Is this considered a Sub-Panel or Not?

Sam, I can only deal with one thread at a time. :D :D :D
 
physis

physis

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Re: Is this considered a Sub-Panel or Not?

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laughing-smiley-003.gif
 
J

john m. caloggero

Senior Member
Re: Is this considered a Sub-Panel or Not?

To: NSMaby, Based on my understanding of your installation, the 200 amp panel ADJACENT to the service panel is a MAIN-LUG panel, supplied from the service panel bussing which is on the load-side of the service disconnect. Therefore, it is NOT supplied from a feeder OCD. It is part of the service distribution, this often done to provide additional branch circuit spaces at the service.
 
roger

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Re: Is this considered a Sub-Panel or Not?

Mr.Caloggero, thank you. :)

Roger
 
physis

physis

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Re: Is this considered a Sub-Panel or Not?

So the conductors after the disconnect are service entrance conductors?
 
roger

roger

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Re: Is this considered a Sub-Panel or Not?

Sam, they aren't conductors, they're buss extensions. :D

Roger
 
infinity

infinity

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Re: Is this considered a Sub-Panel or Not?

So the consensus is that this is a subpanel?
 
K

kiloamp7

Senior Member
Re: Is this considered a Sub-Panel or Not?

Not so fast infinity.

If it is like john m. describes & the main panel has thru-feed lugs with 200A conductors supplying the 200A MLO panel, then think of it as (1) service panel where, maybe (60) OR (72) or (84) - whatever ckts. are desired.

If there is a feeder O/C device in this main panel feeding the MLO panel, then that is a different story.
 
infinity

infinity

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Re: Is this considered a Sub-Panel or Not?

This is the way I see it:

I've got 200 amp service coming into a Main single 200 amp breaker box (exterior).
Click to expand...
An enclosure with a 200amp Main CB on the outside of a garage.

Immediately next to this box, inside the garage is a main lug 200 amp load center.
Click to expand...
A load center on the opposite side of the garage wall with a MLO load center.

It appears that the main disconnect is in the enclosure on the exterior of the building and the Subpanel is on the interior of the garage. Assuming that there is any type of buss between the two enclosures doesn't seem logical from the way the installation was originally described.
 
George Stolz

George Stolz

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Re: Is this considered a Sub-Panel or Not?

Originally posted by nsmaby:
I've got 200 amp service coming into a Main single 200 amp breaker box (exterior). Immediately next to this box, inside the garage is a main lug 200 amp load center.
Click to expand...
What I see when I read this is "I have a 200 amp metermain disconnect (supplied with conductors suitable for 200 amps) feeding a panel in my garage."

If the first means of disconnect is outside, your service disconnect is outside. Your grounding electrodes are connected via grounding electrode conductors at this point, and the grounding and neutrals are to remain separate thereafter.

Neils, as an engineer, why are you performing this work?
 
N

nsmaby

Member
Re: Is this considered a Sub-Panel or Not?

This is set up in this way for safety and convenience reasons - assuming that I get the grounding correct.

If there is arcing or an electrical fire in the house, one could disconnect service without entering the building.

The convenience aspect allows the owner to not have to exit their building to trip a single circuit.

To clarify the original wiring -

We have (both phases + ground) of the service 2/0 wire coming in to the external main breaker panel. This external main breaker panel has ONLY the main 200 amp breaker (service disconnect) with Lugs that go to a Main Lug Panel inside the garage. From the lugs on the external main breaker service disconnect panel to the internal main lug panel, I would have (both phases + ground) 2/0 wire connection within 1.5" or 2" conduit. The total length of this connection is ~24".

I was assuming that effectively I have just moved the main breaker upstream 24", and then could treat the indoor main lug panel as a service panel.

The main question is: Do I need to run 4 wires (and isolate ground and neutral at the inside panel) or 3 wires those 24"?

Thanks for all of your feedback - kind of feel like we're a bunch of lawyers debating our interpretations of the constitution (the code is apparently more subjective than I would have thought).

Niels
 
infinity

infinity

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Re: Is this considered a Sub-Panel or Not?

Main outside = 4 conductors
Main inside = 3 conductors
 
N

nsmaby

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Re: Is this considered a Sub-Panel or Not?

One additional question. Do I need a main breaker on the internal panel? or am I OK with the main breaker being external with only main lugs at the internal panel (I will have > 6 breakers in the internal panel).
 
M

mc5w

Senior Member
Re: Is this considered a Sub-Panel or Not?

You most definitely need to have separate neutral and equipment ground buses in the interior panel. All grounding electrode conductors go to the exterior circuit breaker.

The wires from the exterior circuit breaker to your interior panel or even an exterior panel are NOT bus extensions. The service swithc enclosure is a different enclosure from the branch breaker panel.
 
roger

roger

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Re: Is this considered a Sub-Panel or Not?

Originally posted by mc5w:
You most definitely need to have separate neutral and equipment ground buses in the interior panel. All grounding electrode conductors go to the exterior circuit breaker.
Click to expand...
How many GEC's are there? :roll:

The wires from the exterior circuit breaker to your interior panel or even an exterior panel are NOT bus extensions. The service swithc enclosure is a different enclosure from the branch breaker panel.
Click to expand...
If connected with a metalic raceway, Why?

Roger

[ April 27, 2005, 07:40 AM: Message edited by: roger ]
 
George Stolz

George Stolz

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Re: Is this considered a Sub-Panel or Not?

Roger, with all due respect: Waaaaa? :D

If there is a disconnect outside, that shuts power off to the interior panel, it's two separate boxes. The 24" conduit is holding a feeder for the interior panel. Sure, he could use the metallic conduit as a ground, but that doesn't match up to the quote you posted.

There are frequently two grounding electrode conductors, as a water pipe requires a supplementary electrode.

Me, I'm still awaiting an answer to my question.
Neils, as an engineer, why are you performing this work?
Click to expand...

[ April 27, 2005, 07:50 AM: Message edited by: georgestolz ]
 
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