wire as a main or sub-panel?

[Diesel Dan]

Hooking up power to shop. What I have is the meter base is remote mounted from the building on a pedestal with a 200A disconnect 33' from the panel inside.

We are under the 2008 NEC.

Is the panel considered a main and only needs 3/0,3/0,3/0 of copper or is it a sub panel needing seperate neutral/grounds?

What I have seen in the past and don't assume passes current, or past, code is 3 runs of 3/0 50+ feet from the disconnect to the panel. So it was still considered a main. What that did not have is bare #4 to the main. The #4 was in the meter base and disconnect but stopped there.

If it is a main then do I drag #4 back to the disconnect as well?

Thanks, Dan

 

[dreasoner]

Your disconnect I think is considered your main. It wiil require 2 ground rods to meet current code. The panel is considered a sub panel and will require separate neutral and ground connections. The panel will also have to be grounded.

 

[manwithtools]

Disconnect at the meter is the main. Your shop panel is a sub-panel. BTW, double check on the version of code you are under. I think I heard TN was adopting 2017 sometime in June or July, it could only apply to Metro-Nashville a this point, but it's coming our way out in the country as well.

 

[Diesel Dan]

Build was started under the 2008 code, last year.
It's in Maury county, not as bad as Nashville atea. County even opted out of the residential sprinkler code.

BTW, meter base and disconnects already installed and inspected.

 

[manwithtools]

You should be good to go on code revisions then as you pointed out. I'm actually in Wilson County - well north of Lebanon to be exact. I will update my location now.

Would not live in Metro if they paid me. I like my little piece of paradise, all I can hear right now is boats and birds. Getting ready to add some gunfire to the ambiance though.

 

[Aceman]

Since it's a detached building, use a main breaker panel and install a grounding electrode system. Feed the building with 4 wires and keep your neutrals and grounds separate.

 

[wyliesdiesels]

2008 NEC changed the rules for branch feeders to detached buildings

Now they are required to be 4-wire and since your disconnect is separate, you will meed a 4-wirw feeder as well as an isolated neutral bar.

The panel you get may need a ground bar kit as well.

 

[Diesel Dan]

Panels are Square D, QO series 40 slot 200 amp.

What gauge insulated copper for the ground conductor?

Next to check conduit fill charts as 2" has already been ran. Had already pulled the 3/0 and then a little light bulb came on, late but came on none the less.

Chats with inspector last year never brought this up and sure he's out for the holiday.

 

[jim111]

#6 copper equipment grounding conductor for 200 amp

 

[Diesel Dan]

Thanks, looks like conduit is good.
The above ground vertical sections are 2" sch80, that almost got me.

 

[wyliesdiesels]

Yup #6 cu

 

[Diesel Dan]

The panel you get may need a ground bar kit as well.

Ok, working on the sub-panel for the living quarters.
Panel is a Square D #QO142M200P.

After calling Schneider-electrics help number I've decided to come to the experts!
The help line told me all that was needed to use this panel as a sub was to remove the bonding screw. While I'm no electrical expert I'm sure that isn't enough since the grounds and neutrals are not separated.

Is it possible, or should I say allowable, to remove the two end tabs(yellow arrow) on the ground/neutral bar?
This would separate the ground bars from the neutral. The two ground bars could be jumpered with a #4 conductor then.

The second pic is a little blurry but hopefully you can get an idea of where the pedestal mounted mains are.

 

[Aceman]

Sq D was steering you right, removing the bonding screw allows those NEUTRAL bars to float.

But....you need to buy a separate ground bar and mount it directly to the back of the panel. There should be some prepunched holes for mounting.

Look at the panel cover for the ground bar accessory part # so you get the right one. I don't use Sq D often, they may all be the same, but having a part # doesn't hurt.

 

[Diesel Dan]

Ok, I'm following you.
So there will end up being 4 neutral bars and 2 ground bars.

Or just one long ground bar on one side and all the grounds have to be run over to it?

 

[Aceman]

and 2 ground bars.

Or just one long ground bar on one side and all the grounds have to be run over to it?

Either way is fine, it's your preference.

 

[wyliesdiesels]

One ground bar on each side makes for cleaner panels.

 

[Diesel Dan]

Two ground bars is my preference as well.

Too bad they don't allow for clipping the tabs off, that way you can use all what's already there.
Oh well, off to buy 4 bar kits.

 

[wyliesdiesels]

Two ground bars is my preference as well.

Too bad they don't allow for clipping the tabs off, that way you can use all what's already there.

Oh well, off to buy 4 bar kits.

Why 4?

 

[Diesel Dan]

Still have another 200A panel in the garage that needs to be converted into a sub.

 

[Diesel Dan]

Question on the grounding.

In the past when I installed sub panels they received an additional ground rod but in those cases the sub was 90'+ from the main. With my subs now being so close to the mains is the #6 CU conductor from panel to panel adequate?

If each sub gets a ground rod then I'm looking at 3 separate ground rod systems within a 20' circle.
Wouldn't this have the potential for ground loop interference?

 

[wyliesdiesels]

Question on the grounding.

In the past when I installed sub panels they received an additional ground rod but in those cases the sub was 90'+ from the main. With my subs now being so close to the mains is the #6 CU conductor from panel to panel adequate?

If each sub gets a ground rod then I'm looking at 3 separate ground rod systems within a 20' circle.
Wouldn't this have the potential for ground loop interference?

Only the first main panel(main service or subpanel) on a building needs grounding electrodes.

Not sure why you thought you needed grounding electrodes going to each panel in the same structure. Distance has nothing to do with it.

And you are confusing different types of grounding.

Grounding electrodes and the ground wire that goes between panels are 2 different animals serving different purposes.

And no you wouldnt have any kind of interference if you have more grounding electrodes than necessary. You can have as many ground rods as you want and the only thing you would hurt is your wallet.

This is because grounding electrodes do not carry current under normal operation. Their main function is for grounding lightning. When i use to work on cell sites and dispatch centers, we would install quite a few ground rods(sometimes 30) connected in a grid and mesh pattern.

It seems you are confused on functionality, so it would be good to read post #4, in the electrical FAQs thread here: https://www.garagejournal.com/forum/showthread.php?t=356460

 

[Diesel Dan]

Only the first main panel(main service or subpanel) on a building needs grounding electrodes.

Not sure why you thought you needed grounding electrodes going to each panel in the same structure. Distance has nothing to do with it.

In the past the sub panels were for detached shops run off the house main. So in those cases they were not the same structure.

FWIW I wouldn't think I need ground rods either but in the end it's not my call.
Since my meter and mains are pedestal mounted off of the house it in some ways makes it a detached structure at least that's what I gathered from the inspector last time he was out.

 

[Diesel Dan]

It seems you are confused on functionality, so it would be good to read post #4, in the electrical FAQs thread here: https://www.garagejournal.com/forum/showthread.php?t=356460

Nice post, I did not see it.

I'm telling you guys you REALLY need to buy a house w/o internet capabilities(4GLTE included)!
Time spent on forums drastically gets cut down.

 

[wyliesdiesels]

In the past the sub panels were for detached shops run off the house main. So in those cases they were not the same structure.

FWIW I wouldn't think I need ground rods either but in the end it's not my call.

Since my meter and mains are pedestal mounted off of the house it in some ways makes it a detached structure at least that's what I gathered from the inspector last time he was out.

I dont think i explained it quite right.

Ok so you have a pedestal mounted meter that feeds several structures?

Each FIRST panel in each detached structure off that meter needs 2 rods. IF you feed an additional subpanel from that first panel in the same structure, then no electrodes are needed for that second or subsequent panels after that.

Essentially, each building should have one set of rods. Each panel doesnt need them. Just the first panel in the chain needs them.

 

[Diesel Dan]

You are doing a good job trying to explain, it's my lack of description and pictures that isn't helping.

What I basically have is one structure. A small 2 story house with an attached 40x48x17.5 garage.

The pedestal mounted meter/main has two 200A disconnects with 5 ground rods 10' apart. One disconnect for the living quarters and one for the garage. So there is no chain of panels inside the building.

 

[wyliesdiesels]

You are doing a good job trying to explain, it's my lack of description and pictures that isn't helping.

What I basically have is one structure. A small 2 story house with an attached 40x48x17.5 garage.

The pedestal mounted meter/main has two 200A disconnects with 5 ground rods 10' apart. One disconnect for the living quarters and one for the garage. So there is no chain of panels inside the building.

Was the place like that when you bought it?

Thats a big code violation.

Not suppose to have more than one feed to a structure.

The panel in the garage should be fed from the house panel or vise versa with only one feeder coming from the meter.

Someone wasted money on ground rods as well.

 

[walrus]

[/b]

Was the place like that when you bought it?

Thats a big code violation.

Not suppose to have more than one feed to a structure.

The panel in the garage should be fed from the house panel or vise versa with only one feeder coming from the meter.

Someone wasted money on ground rods as well.

Isn't the pedestal the structure in this case, so one service to that structure(pedestal) and then sub panels to house and then sub to garage?

 

[Diesel Dan]

Was the place like that when you bought it?

Thats a big code violation.

Not suppose to have more than one feed to a structure.

The panel in the garage should be fed from the house panel or vise versa with only one feeder coming from the meter.

Someone wasted money on ground rods as well.

The wiring of the pedestal was discussed about a year ago on here.

A Ufer ground wasn't used because the contractor didn’t leave me a ground connection to the footer when it was poured.

For running power to the building it was being framed right then and I showed the inspector where I was going to burythe conduit and he didn't say anything about not doing what I have done.

So the $64K question is what now?

 

[wyliesdiesels]

Isn't the pedestal the structure in this case, so one service to that structure(pedestal) and then sub panels to house and then sub to garage?

The garage is attached to the house.

So that building has 2 different feeds going to it.

Has nothing to do with the meter location.

 

[walrus]

The garage is attached to the house.

So that building has 2 different feeds going to it.

Has nothing to do with the meter location.

Yes, but the main is on the pedestal so the feeders aren't services .

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[wyliesdiesels]

Yes, but the main is on the pedestal so the feeders aren't services .

Sent from my SM-G950U using Tapatalk

You keep saying service and i keep saying feed. Im not sure why you keep using the word service. And the main has nothing to do with it either. The house panel or garage panel, whichever would be the primary subpanel, is required to have a main disconnect if there are more than 6 breaker handles.

No matter how you twist the wording around, the code is the same.

there cant be more than one power source to a building. The pedestal is separate from the building and is inconsequential to what is going on in the house.

The house is one structure so there should only be one feed from the meter to it. The OP has 2 and this is a no-no.

I dont know any other way to explain it.

This subject is brought up multiple times per week on here.

No matter what type of feeder or source it is, the answer is always the same.

 

[walrus]

I always thought one service to a residential building , not one feed. Appreciate the discussion

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[Diesel Dan]

there cant be more than one power source to a building. The pedestal is separate from the building and is incomsequential to what is going on in the house.

The unit is one structure so there should only be one feed from the meter to it. The OP has 2 and this is a no-no.

I dont know any other way to explain it.

What about row housing /condos?
The home we rented for a few months was the end unit and all the meters/disconnects were on the side of our unit. Each single story, single family unit, had its own panel.

This subject is brought up multiple times per week on here.

I've seen many questions on detached sub panels over the years regarding 3 vs 4 wire feeds, separated neutral /grounds, wire size etc but not my issue.

Over the last year I've shown or discussed this system with 2 electrical inspectors and multiple contractors that did electrical work and nobody voiced any concerns.

So I'm looking at a 400 amp meter feeding one 200A disconnect, to a 200A primary sub panel feeding another secondary 200A sub? Which includes abandoning one disconnect and associated wiring.

Or, remove both 200A disconnects, conduit, wiring to install a 400a disconnect, larger conduit and wiring?

This should be entertaining at least.

 

[wyliesdiesels]

What about row housing /condos?
The home we rented for a few months was the end unit and all the meters/disconnects were on the side of our unit. Each single story, single family unit, had its own panel.

Are they all detached?

That would still be one feed to each building since each has one subpanel.

Meter stacks with main disconnects. Each main disconnect is connected to one branch feeder that feeds the subpanel in each single family building.

That is a different scenario than what you have.

I've seen many questions on detached sub panels over the years regarding 3 vs 4 wire feeds, separated neutral /grounds, wire size etc but not my issue.

Over the last year I've shown or discussed this system with 2 electrical inspectors and multiple contractors that did electrical work and nobody voiced any concerns.

So I'm looking at a 400 amp meter feeding one 200A disconnect, to a 200A primary sub panel feeding another secondary 200A sub? Which includes abandoning one disconnect and associated wiring.

Or, remove both 200A disconnects, conduit, wiring to install a 400a disconnect, larger conduit and wiring?

This should be entertaining at least.

An example would be feeding the garage subpanel from the house subpanel. Or vise versa.

If the garage was DETACHED then the setup you currently have would be legal.

Here's the code:

NEC 2011 225.30

Number of Supplies. A building or other structure that is served by a branch circuit or feeder on the load side of a service disconnecting means shall be supplied by only one feeder or branch circuit unless permitted in 225.30(A) through (E).

And none of the exceptions in (A) through (E) apply to your situation.

 

[Diesel Dan]

Are they all detached?

No, rows of single family units probably 10-15 per row with shared walls and attached 2 car garages.

 

[wyliesdiesels]

No, rows of single family units probably 10-15 per row with shared walls and attached 2 car garages.

That makes no difference either since the origin of the service is on the same building.

Thats the same scenario as having, instead of your meter pedestal, a main service panel on your house, and then feeding your 2 subpanels from that.

Its only one feed.

Now instead move that meter stack to a different building and run the individual feeders to each subpanel in each unit and you have a violation.

And thats the same thing you have.

 

[mm08822]

There are differences in single family dwelling units and multiple family units. This is not in the original scope of this thread.
As Wylie pointed out in the row house/condo example there is one service to the building and each “tenant” has their own “service” which is actually a sub-panel (4-wire) fed from the individual Main Disconnects for each independent living unit after the respective metering. Each of the Unit’s Main Disconnects is fed from one set of service entrance conductors.

There are some exceptions to this rule, but it is for rather large services (+1000A) or a building that extremely large where one common point of service attachment is impractical. These situations need to be pre-approved, documented and placards placed at each point of service to indicate what is fed from this location. This is common in commercial and industrial settings where qualified personnel are present (not the case for residential).

The OP’s situation is a single family dwelling. Accessory buildings may have a single feeder to each. OP states his shop is attached to the house. Really need to understand what he means by attached. Some pics would help. Typically once an addition is made to an existing structure(connected), it is considered the same building. Hence only one service or in this case, only one feeder to a primary sub-panel is permitted as already stated. Sub-panels off of a “primary” sub-panel is permitted .

An accessory building is defined as a physically separate building from any other building. There is some wording in the NEC definition of a “Building” stating: A structure that stands alone or is separated from adjoining structures by firewalls. Again, this is permitted with justifiable need in commercial and industrial settings and extremely rare for a residential setting.

The AHJ interpretation and the building code definitions of this particular build would dictate. To me it appears to be one building with a simple addition since they are “attached”.

 

[Diesel Dan]

New construction, no addition.

 

[mm08822]

What I basically have is one structure. A small 2 story house with an attached 40x48x17.5 garage.

New construction, no addition.

So the house it completely physically separated from the garage? I.E. - there is dirt in between each building?

 

[wyliesdiesels]

Looks to me like the garage is added on to the existing main house.