Putting a disconnect into an mlo panel.

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jimknowle

Member
Location
maine
I went to a house today with a 100A meter disconnect outside on a pedestal. Urd was run from pedestal directly to a 200A Mlo panel in the basement. Now this sub panel obviously needs a disconnecting means. Is it permissible to install a 200A main breaker into the sub panel even though its a 100a service or should I back feed the panel with a 100a breaker with an attachment bracket. (200a sub panel will not accept a 100A main breaker)
 

rhovee

Member
You mentioned that there is a 100 amp disconnect at the meter. If the disconnect is an overcurrent protective device ( breaker or fuse), then you do not need another main breaker inside. However, the neutrals and grounds should be isolated at the panel in the house. The overcurrent protection at the meter is protecting the conductors and the panel to a maximum of 100 amps. There is no need to change the panel or add a breaker.
 

Smart $

Esteemed Member
Location
Ohio
You mentioned that there is a 100 amp disconnect at the meter. If the disconnect is an overcurrent protective device ( breaker or fuse), then you do not need another main breaker inside. However, the neutrals and grounds should be isolated at the panel in the house. The overcurrent protection at the meter is protecting the conductors and the panel to a maximum of 100 amps. There is no need to change the panel or add a breaker.
That is correct.

However, the pedestal is considered a separate structure by the interpretation of most on this forum (BTW, requiring its own GES). This makes the house an additional building or structure on the premises, supplied by a feeder, and thus requiring a disconnecting means outside or inside nearest point of entrance (actual ocpd is not required though).

The question here is whether the AHJ requires a disconnecting means at the house.
 

mwm1752

Senior Member
Location
Aspen, Colo
How old is the service? Is the meter/ped "within sight" of the structure? True this forum has great disagreements with what is a structure and "if" manufactered Electrical equipment is indeed a structure. I agree the OCPD is not needed as the service is protected by the ped 100A OCPD therefore the 200A OCPD could be condsdered a disconnecting means -- the issue I would querry is now you insinuate to someone that the house has a 200A service and is capable of the load by this installation. Some will not look for the meter/ped and as you describe the service comming into the panel appears unfused. Backfeed a 100 A breaker & secure it properly by code is my opinion for best practice.
 

david

Senior Member
Location
Pennsylvania
How old is the service? Is the meter/ped "within sight" of the structure? True this forum has great disagreements with what is a structure and "if" manufactered Electrical equipment is indeed a structure. I agree the OCPD is not needed as the service is protected by the ped 100A OCPD therefore the 200A OCPD could be condsdered a disconnecting means -- the issue I would querry is now you insinuate to someone that the house has a 200A service and is capable of the load by this installation. Some will not look for the meter/ped and as you describe the service comming into the panel appears unfused. Backfeed a 100 A breaker & secure it properly by code is my opinion for best practice.

Why is it significant if the pedestal is a structure or not, in relationship to wither the Dwelling needs a disconnect for the feeder supplying the dwelling.
 

Smart $

Esteemed Member
Location
Ohio
Unless it grew there it must have been built or constructed. That makes it a structure. :cool:
The requirement is, "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." Just as the distance "inside nearest the point of entrance" is subject to interpretation, so can the distance outside. It is not required for an outside disconnecting means to be on the building or structure, and the requirement for a disconnecting means for a separate structure is no different.

Where a service disconnecting means is located say 6' from the building or structure supplied, is it really necessary, from a safety perspective, to deem these as separate structures and require another disconnecting means on or in the supplied building or structure?
 

iwire

Moderator
Staff member
Location
Massachusetts
Why is it significant if the pedestal is a structure or not, in relationship to wither the Dwelling needs a disconnect for the feeder supplying the dwelling.

Because if the pedestal and the building were just 'one structure' there would be no requirement for a disconnect in the building.

On the other hand if there are separate structures the rules in part II of article 225 kick in
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
Now this sub panel obviously needs a disconnecting means.
I disagree with this statement. It is not the sub panel that needs a disconnecting means, it is the building that needs a disconnecting means. There is some room for interpretation as to whether the disconnect associated with the meter would qualify as the building's disconnecting means. If it does not, then you don't need to modify the MLO panel. You can simply insert a 100 amp non-fused disconnect immediately upstream of the panel. There are other solutions as well.

 

Smart $

Esteemed Member
Location
Ohio
Because if the pedestal and the building were just 'one structure' there would be no requirement for a disconnect in the building.

On the other hand if there are separate structures the rules in part II of article 225 kick in
I think you are so stuck on your interpretation that you are not open to alternative legitimate interpretations.

Here's one such interpretation. By the same definition to which you are saying the pedestal is a separate structure, I can also say the pedestal, the house, and wiring in between are all the same structure. They are an assembly of parts built or constructed AND joined together. The wiring in between is empirical evidence they are joined. To say the pedestal and house are separate structures, you have to use parameters which are not actually written in the Code.
 

iwire

Moderator
Staff member
Location
Massachusetts
I think you are so stuck on your interpretation that you are not open to alternative legitimate interpretations.

I am stuck on what a structure is that is for sure. :D

It is a short and simple definition, I don't see much room for interpretation. :)

Structure. That which is built or constructed.

I think people are stuck on is that they picture a structure as a building ... and certainly a building is a structure. But part II of 225 deals with "Buildings or Other Structures" so clearly the NEC recognizes that there are structures that are not buildings.


Here's one such interpretation. By the same definition to which you are saying the pedestal is a separate structure, I can also say the pedestal, the house, and wiring in between are all the same structure. They are an assembly of parts built or constructed AND joined together. The wiring in between is empirical evidence they are joined. To say the pedestal and house are separate structures, you have to use parameters which are not actually written in the Code.

Now here I don't disagree with you in the least.* What is separate? That seems to be entirely up to the AHJ.

IMHO, if the pedestal was, lets say 25' or less from the building, not blocked by anything I would not be surprised if the inspector / AHJ called them the same structure.

On the other hand, 200' away, on the other side of the shrubs I would expect that to be called a separate structure.

And if it happened to be just a meter pedestal without service disconnecting means with it I would say it may not exist as far as the NEC is concerned. (90.2(B)(5)





*(I do find your inclusion of the wiring between them proving they are 'joined' in the sense the NEC is concerned with for article 225 a long stretch. If we read it that way there is never a separate building or structure supplied by a feeder. )
 

Smart $

Esteemed Member
Location
Ohio
...What is separate? That seems to be entirely up to the AHJ.

IMHO, if the pedestal was, lets say 25' or less from the building, not blocked by anything I would not be surprised if the inspector / AHJ called them the same structure.

On the other hand, 200' away, on the other side of the shrubs I would expect that to be called a separate structure.

And if it happened to be just a meter pedestal without service disconnecting means with it I would say it may not exist as far as the NEC is concerned. (90.2(B)(5)

*(I do find your inclusion of the wiring between them proving they are 'joined' in the sense the NEC is concerned with for article 225 a long stretch. If we read it that way there is never a separate building or structure supplied by a feeder. )
And you covered my point quite admirably... :D
 

sparkyrick

Senior Member
Location
Appleton, Wi
That is correct.

However, the pedestal is considered a separate structure by the interpretation of most on this forum (BTW, requiring its own GES). This makes the house an additional building or structure on the premises, supplied by a feeder, and thus requiring a disconnecting means outside or inside nearest point of entrance (actual ocpd is not required though).

The question here is whether the AHJ requires a disconnecting means at the house.

A pedestal is not a structure.
 

iwire

Moderator
Staff member
Location
Massachusetts
The requirement is, "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." Just as the distance "inside nearest the point of entrance" is subject to interpretation, so can the distance outside. It is not required for an outside disconnecting means to be on the building or structure, and the requirement for a disconnecting means for a separate structure is no different.


And I don't disagree, I am very firm on what a structure is. As to what is 'separate' that is very open to interpretation.

Where a service disconnecting means is located say 6' from the building or structure supplied, is it really necessary, from a safety perspective, to deem these as separate structures and require another disconnecting means on or in the supplied building or structure?

No, not in my opinion. I don't think in all my many posts and rantings about structures have even hinted that I think that. :)
 

mwm1752

Senior Member
Location
Aspen, Colo
I am stuck on what a structure is that is for sure. :D
It is a short and simple definition, I don't see much room for interpretation. :)

I think people are stuck on is that they picture a structure as a building ... and certainly a building is a structure. But part II of 225 deals with "Buildings or Other Structures" so clearly the NEC recognizes that there are structures that are not buildings.

So a hole hawg , range, Dryer, meter ped, panelboard, kitchen cabinets are structures ---- are they not all That which is built or constructed. ? BTW the definition did come from the building codes. I asked Mr Sargent in a webinar if he considered a free standing service a structure -- No he replied it is considered electrical equipment.
 
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mwm1752

Senior Member
Location
Aspen, Colo
2002 NEC introduced the definition -- below are contradicting statements the panel members had unanimious votes on --- neither definition was inserted as per recommended revised -- no wonder there is confusion. Notice the meter ped part was to be included with the revision " or a portion thereof. " if it was used.The debate continues

1- 109 - (100-Structure (new)): Hold this is the ROC
SUBMITTER:
Frederic P. Hartwell , Hartwell Electrical Services, Inc.
COMMENT ON PROPOSAL NO: 1-188
RECOMMENDATION: Revise as follows:
"A combination of materials assembled at a fixed location to give support or shelter."
SUBSTANTIATION: This definition has a more descriptive quality that will not be misapplied to manufactured items placed as a unit. It conforms to the present BOCA definition, namely: "a combination of materials assembled at a fixed location to give support or shelter, such as a building, framework, retaining wall, tent, reviewing stand, platform, bin, fences over six feet high, sign, flagpole, recreational tramway, mast for radio antenna, or the like."
PANEL ACTION: Hold.
PANEL STATEMENT: The Panel concludes that this comment contains new material and desires to "hold" this comment. The panel desires that Proposal 1-188 continue to be accepted.
NUMBER OF PANEL MEMBERS ELIGIBLE TO VOTE: 13
VOTE ON PANEL ACTION:
AFFIRMATIVE: 13
1- 189 - (100-Structure (New) ): Accept in Principle SUBMITTER: James H. Maxfield, Dover, NH this is the ROP
RECOMMENDATION:
Add a new definition to read as follows:
Structure. That which is constructed or built or erected or a portion thereof.
SUBSTANTIATION: The word structure is used throughout the NEC in several locations but is not defined. The definition is intentionally broad so as to include within the NEC everything that is built whether it is constructed solely from electrical components or not. For example, the addition of the definition would clarify the fact that the NEC considers a meter pedestal a structure.
PANEL ACTION: Accept in Principle.
PANEL STATEMENT: The panel prefers the definition found in Proposal 1-188. See Proposal 1-188.
NUMBER OF PANEL MEMBERS ELIGIBLE TO VOTE: 13
VOTE ON PANEL ACTION:
AFFIRMATIVE: 12
NOT RETURNED: 1 Macias
 

Smart $

Esteemed Member
Location
Ohio
...BTW the definition did come from the building codes. I asked Mr Sargent in a webinar if he considered a free standing service a structure -- No he replied it is considered electrical equipment.
I have tried to express that sentiment in other posts, but it continually gets shot down by other participants. I think the main distinction is free-standing electrical equipment vs. secured to a supporting structure.
 

iwire

Moderator
Staff member
Location
Massachusetts
So a hole hawg , range, Dryer, meter ped, panelboard, kitchen cabinets are structures ---- are they not all

In my personal opinion per the current definition they are structures. Being a structure does not prohibit an item from also being equipment.

They are all certainly built or constructed.

I asked Mr Sargent in a webinar if he considered a free standing service a structure -- No he replied it is considered electrical equipment.

I agree it is electrical equipment, I feel it also happens to be a structure.

Can you explain to me how the NEC can consider a light pole a structure (see 225.32 exceptions to support that view) yet a pedestal supporting electrical equipment is not a structure?
 

jimknowle

Member
Location
maine
Charlie B, you are correct to say the sub panel does not need the disconnect, it is really the house that needs it. Now, I WILL be putting in a disconnect for the house where the feeders enter. My question was what would be the easiest way to do it. Backfeeding a 2-pole 100A breaker and using an attachment bracket has to be the easiest way to legally put in a disconnect for the house. On a side note, I am very surprised to see so many different opinions on a very, very, common service. There really needs to be some clarification in the next code cycle.
 
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