detached garage

[George Stolz]

What is the rating of the disconnecting means if you have more than one (no single main, either two or up to six)? Must each be 60, or can you have two 30's? How about six single pole 15's?

I don't know. I submitted a proposal for the 2008 to clear up how this is figured, and got no answer. IMO, it is most reasonably determined from the rating of the feeder supplying the structure, but there is no method given in Article 225, IMO.

Since a L&ABCPB can't be service equipment by it's listing, then a main disconnect is the easiest way to point to something and say, "I have a 60A disconnect on my detached structure," IMO.

I see nothing concrete that says a 40A feeder can't supply a 60A main breaker on the detached building to meet the requirement. In my opinion.

 

[iwire]

What is the rating of the disconnecting means if you have more than one (no single main, either two or up to six)? Must each be 60, or can you have two 30's? How about six single pole 15's?

Thats a darn good question and I do not really know the answer. I think the answer is no.

If we look at service requirements you can combine the rating per 230.80

But when we go to 225 for feeders I do not see anything allowing for a combined rating.

As a matter of fact in 225.39 it says in part 'in no case shall the rating be lower than specified in (A)(B)(C) or (D).

 

[iwire]

I see nothing concrete that says a 40A feeder can't supply a 60A main breaker on the detached building to meet the requirement. In my opinion.

I agree nothing in concrete or even oatmeal.

30 amp feeder to a 60 amp disconnecting means sounds good to me.

 

[George Stolz]

Actually, I take that back. I got an answer, I just didn't like it so I conveniently forgot it, I think.

4-24 Log #1400 NEC-P04 Final Action: Reject
(225.39)
______________________________________________________________
Submitter: George Stolz, II, Pierce, CO
Recommendation: Delete this section and its subsections.

Substantiation: Currently, this section is unclear as to what the ?rating? requirement is referring to. Some view it as an addition of the ratings of the breakers installed at the separate structure in the panel(s). Some view it as a rating requirement for the enclosure itself. Some even view it as the rating for the OCPD that is installed at the supply side at the originating building, protecting feeder conductors. In any case, it appears evident that the size of conductors feeding the disconnecting means are truly what constitute the capacity of the system, and those conductors are sized and installed independent of the requirements laid out in this section.

Given the requirement given in 225.36, it appears that the purpose of this area of Article 225 is geared towards the ease of future expansion: should a separate structure at some point be supplied by a separate service, such an improvement would be made easier if the existing equipment were already suitable for such use. The requirements of this area are a reflection of nearly identical requirements of Article 230.

However, section 90.1(B) states that compliance with the NEC ?...will result in an installation that is essentially free from hazard but not necessarily efficient, convenient, or adequate for good service or future expansion of electrical use.? There is no hazard that is prevented by this section, it appears to exist solely for future expansion, which is explicitly outside the desired scope of the NEC per 90.1.

Further, if such an improvement is made to a structure at a later date, it is probable that most if not all equipment supplying that structure will be
removed due to age or fundamental changes in the use of the building requiring greater capacity. Given the rampant misunderstanding of the nature of this section, if it is retained, the language should be clarified to reflect what exact component of the system is to bear the ratings listed in (A) through (D).

Panel Meeting Action: Reject

Panel Statement: The title of the section clearly states the ?Rating of Disconnect?. Simply stated, this is the minimum ampacity rating of the disconnecting means regardless of type. The fact that it is service rated does not establish an ampacity rating. Future expansion has nothing to do with this requirement.

Number Eligible to Vote: 10
Ballot Results: Affirmative: 10​

I didn't get a clear answer on why it needed to be service rated, but it is clear they're talking about the handle itself when referring to the disconnect.

IMO, the handles could be added up. I remember discussing this with Bryan Holland the last time, and in his opinion, each handle would have to be worth 60A.​

 

[iwire]

I didn't get a clear answer on why it needed to be service rated, but it is clear they're talking about the handle itself when referring to the disconnect.

I think they could have been more clear. But at least it is something and thanks for posting it.

IMO, the handles could be added up. .[/LEFT]

Given the similarities between service and feeder disconnecting means ratings and the fact 230 specifically says we can combine I see nothing in 225 allowing the same combining of handles.

It makes no sense to me but then again I would have been very happy if they accepted your proposal. The whole section seems like a waste.

'It's not for the future.....

But we gave you a minimum without regard for the present....

 

[M. D.]

Western section IAEI

September 18-20, 2006​

In a residential garage, on a sub-panel installation of 4- two wire branch circuits I say that the
minimum feeder ampacity should be 60Amps, based on the fact that the disconnecting means
must be rated at 60 Amps by code. My co-worker says that it is based on the computed load and
could be 40Amps or 50Amps​

Panel Response:​

225.5 requires that the feeder conductor size be based on Article 220. The​

requirement in 225.39(D) states that the disconnecting means must be rated at least 60 amperes.
This could be a combination of the branch circuits (e.g. 4 ? 15A branch circuits).​

I would say ,where does it say it is prohibited to add the ratings of the more than one disconnect means allowed?? I think this panel got it right.

 

[M. D.]

I just found this one,..

4-25 Log #2156 NEC-P04 Final Action: Accept in Principle
(225.39)

______________________________________________________________

TCC Action: The Technical Correlating Committee understands that the
panel action on Proposal 4-22 adds the word ?calculated? to the wording
in this panel action.
Submitter: James Grant, Rochester, NH

Recommendation: Revise text to read:
225.39 Rating of Disconnect. The feeder or branch-circuit disconnecting
means shall have a rating of not less than the load to be supplied, determined in
accordance with Parts I and II of Article 220 for branch circuits, Parts III or IV
of Article 220 for feeders, or Part V of Article 220 for farm loads. Where the
branch circuit or feeder disconnecting means consists of more than one switch
or circuit breaker, as permitted by 225.33, the combined ratings of all the
switches or circuit breakers used shall be permitted. In no case shall the rating
be lower than specified in 225.39(A), (B), (C), or (D).

Substantiation: When using up to six disconnects, as permitted by 225.33, the
present wording requires all the disconnects to be rated at the value as
determined by 225.39. This revised article would directly parallel with 230.80.
For the same reason that 230 has it for calculating the service, it would allow
the value of some of the breakers to be used as the rating of the disconnect for
the feeder or branch circuit.
The panel?s statement to 4-36 Log #609 NEC-P04 in the 2005 report of
proposals made the following comment:
?Since a disconnect is a device or group of devices, permission is already
inherent to add each device to reach a total rating in compliance with this
section.? The new revised text will eliminate any confusion that there is
inherent permission for breakers to be additive in calculating the rating of a
disconnect.

Panel Meeting Action: Accept in Principle

Accept the added sentence with the exception of the word ?used? and revise
the proposed text by changing ?combined ratings of? to ?combining the ratings
of? and add the phrase ?for determining the rating of the disconnecting means?
to the text before ?shall be permitted? in the NEC to read as follows: ?The
feeder or branch-circuit disconnecting means shall have a rating of not less
than the load to be supplied, determined in accordance with Parts I and II of
Article 220 for branch circuits, Parts III or IV of Article 220 for feeders, or Part
V of Article 220 for farm loads. Where the branch circuit or feeder
disconnecting means consists of more than one switch or circuit breaker, as
permitted by 225.33, combining the ratings of all the switches or circuit
breakers for determining the rating of the disconnecting means shall be
permitted. In no case shall the rating be lower than specified in 225.39(A), (B),
(C), or (D)?
Do not revise any other text within this section.

Panel Statement: The word ?used? was deleted and text was added to the
proposed new sentence to provide clarity and to be more specific in what
constitutes the combined ratings of the disconnecting means for feeder or
branch circuit disconnecting means for separate buildings or structures.

Number Eligible to Vote: 10
Ballot Results: Affirmative: 10
_______________________________________

​

_______________________​

 

[George Stolz]

That's an awesome find, M.D.

So, in the 2008 it will be clearer that adding the handles together will be how the rating is determined. Unfortunately, we still won't be able to make much use of this, as the listing of the Lighting & Appliance Branch Circuit Panelboard shall still require a main handle to make it suitable for service equipment.

I wish I had rememberred to submit that proposal to delete 225.36, I would have been interested to see their reply to that.

 

[binney]

There's no argument that the 4-wire system is legal, and was legal. My question is 15-18 years ago, when this was installed, was it required to have the ground rods. If not, IMO the existing installation should be grandfathered in, it is not the homeowners responsibility to bring there home up to current code.

 

[iwire]

There's no argument that the 4-wire system is legal, and was legal. My question is 15-18 years ago, when this was installed, was it required to have the ground rods.

Regardless of it being a 3 or 4 wire feeder I believe the NEC has required grounding electrodes at separate structures for a long time.

IMO the existing installation should be grandfathered in, it is not the homeowners responsibility to bring there home up to current code.

From a code perspective that may well be true.

In this case it has to do with sale of the home, the buyers can ask for anything they want, the sellers can agree or not.

 

[paul]

There's no argument that the 4-wire system is legal, and was legal. My question is 15-18 years ago, when this was installed, was it required to have the ground rods. If not, IMO the existing installation should be grandfathered in, it is not the homeowners responsibility to bring there home up to current code.

You also have the counter argument as to whether or not a permit was pulled and the work was inspected. As iwire said, you can agree to do the extra work, or you can tell the prospective buyer that you're not going to do the work.

 

[480sparky]

There's no argument that the 4-wire system is legal, and was legal. My question is 15-18 years ago, when this was installed, was it required to have the ground rods.

A bit of history here:

250.83. Made and Other Electrodes. Where none of the electrodes specified in Section 250-81* is available, one or more of the electrods specified in (b) through (d)** below shall be used. Where practicable, made electrodes shall be embedded below permanent moisture level. Made electrodes shall be free from nonconductive coatings, such as paint or enamel. Where more than one electrode is used, each electrode of one grounding system (including that used for lightning rods) shall not be less than 6 feet (1.83 m) from any other electrode of another grounding system.

* 250.81 states "...If available on the premises at each building or structure..." and then refers to water pipe, metal frame, concrete-encased electrodes and ground rings.
** (c) refers to Rod & Pipe Electrodes

This wording is the same from 1978 to 1993. I don't know about '96 or '99 as I can't find my books from those years. By '02 similar wording had been introduced and moved to Article 250-32.

Asterik notes are my addition and not part of the old Codes.

 

[M. D.]

That's an awesome find, M.D.

..... we still won't be able to make much use of this, as the listing of the Lighting & Appliance Branch Circuit Panelboard shall still require a main handle to make it suitable for service equipment.

I wish I had rememberred to submit that proposal to delete 225.36, I would have been interested to see their reply to that.

Thanks, hey george this is a good article on the ,....hmmm the issue of panel boards and the restrictions.
http://www.iaei.org/subscriber/magazine/98_e/closerlook.htm

 

[George Stolz]

Doc, that's an interesting read, but I'm not sure of the conclusion I'm supposed to draw from it.

 

[M. D.]

Doc, that's an interesting read, but I'm not sure of the conclusion I'm supposed to draw from it.

Just thought it was interesting , to see how some things hang around to the point where no one knows why they are still hanging

 

[George Stolz]

Another thing that I find refreshing about that article is, it shows someone actually cares enough about the issue to think deeply about it to the degree the author did.

 

[M. D.]

Yeah ,it almost gives one faith in the process

 

[M. D.]

That's an awesome find, M.D.

Unfortunately, we still won't be able to make much use of this, as the listing of the Lighting & Appliance Branch Circuit Panelboard shall still require a main handle to make it suitable for service equipment. ...

George ,if the breaker feeding this panel is not greater than the rating of the sub panel then the six disconnect rule could be used,.. do you agree?

This is from NFPA diegest

.........In all likelihood, the panelboard supplying the pool equipment is a lighting and appliance branch circuit panelboard, as covered in Section 408.34(A). Lighting and appliance branch circuit panel­boards are required to be individu­ally protected on the supply side by not more than two main circuit breakers or two sets of fuses. This requirement would seem to pre­clude using the “six disconnect rule” at this panelboard.
However, Exception No. 1 to Section 408.36 allows you to omit individual overcurrent protection in the panelboard as long as the over current device protecting the feeder conductors that supply the panelboard has a rating or setting not greater than the rating of the panelboard. Assuming that the rating or setting of the feeder overcurrent protective device is not greater than the rating of the panelboard, the six disconnect rule at the panelboard location is permitted......
.

Jeff Sargent, of NFPA’s Electrical Engineering Department, has been a master electrician, inspector, instructor, consultant, and author. He was senior editor of the 2005 National Electrical Code Handbook and is executive secretary to the NFPA Electrical Section, as well as staff liaison to several NFPA technical committees.

 

[George Stolz]

George ,if the breaker feeding this panel is not greater than the rating of the sub panel then the six disconnect rule could be used,.. do you agree?

No, I don't. The problem with a branch circuit or two (using a neutral) as the pair of handles toward the six-disconnect rule is a combination of 225.36 and 110.3(B).

Take a look at this picture, that Bob posted in the original thread where we figured most this out:

It is the listing of the panel that is pooching the deal; the panelboard, inside the same structure as the origin of it's feeder, is properly protected. Move the panelboard to another structure, it's still properly protected from overcurrent.

The problem is, 225.36 comes swinging down like a guillotine and butting itself into the equation. Now, if the panel's listing states "suitable for service equipment" with conditions attached that the NEC may or may not have intended (less than six throws and not being used as a L&ABCPB), we can't use it anymore without the main - if it is a L&ABCPB.

Here is midway through the thread that the picture came from.

 

[angryhalfinch]

So because a garage has one light and two general purpose outlets it is considered being supplied by a L&ABCPB? When is it considered just a branch circuit? When does it come into play that you can use 6 snap switches as your disconnects in a residential application? I don't have the problem doing the work, I want to know the facts, that's the difference in this case.