Can a subpanel lay flat on a shelf?

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Re: Can a subpanel lay flat on a shelf?

Joe as I posted 'over there' I think 110.26 requirements and perhaps 110.3(B) are the only ones that relate directly to this.

240.33 does not prohibit horizontal mounting.

240.33 Vertical Position.
Enclosures for overcurrent devices shall be mounted in a vertical position unless that is shown to be impracticable. Circuit breaker enclosures shall be permitted to be installed horizontally where the circuit breaker is installed in accordance with 240.81. Listed busway plug-in units shall be permitted to be mounted in orientations corresponding to the busway mounting position.
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It seems 'impracticable' is a call for the local inspector to make.

I doubt when the CMP used the word horizontal they meant horizontal on it's back, but horizontal is horizontal. ;)

Bob
 
Re: Can a subpanel lay flat on a shelf?

Originally posted by iwire:
Joe as I posted 'over there' I think 110.26 requirements and perhaps 110.3(B) are the only ones that relate directly to this.

240.33 does not prohibit horizontal mounting.

240.33 Vertical Position.
Enclosures for overcurrent devices shall be mounted in a vertical position unless that is shown to be impracticable. Circuit breaker enclosures shall be permitted to be installed horizontally where the circuit breaker is installed in accordance with 240.81. Listed busway plug-in units shall be permitted to be mounted in orientations corresponding to the busway mounting position.
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It seems 'impracticable' is a call for the local inspector to make.

I doubt when the CMP used the word horizontal they meant horizontal on it's back, but horizontal is horizontal. ;)

Bob
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Contrary to a post 'over there', 240.33 DOES NOT allow the breakers to be installed with 'on' being up.

240.33 is referring to the enclosure being horizontal, not the breakers. In fact, 240.33 includes this restriction "where the circuit breaker is installed in accordance with 240.81".


240.81 Indicating.
Circuit breakers shall clearly indicate whether they are in the open ?off? or closed ?on? position.

Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the ?up? position of the handle shall be the ?on? position.

Thus, the ONLY enclosures allowed to be installed in the horizontal position are those enclosures listed and labeled for use with the panelboard section installed vertically in the horizontal enclosure. 240.33 is a very restrictive option.
 
Re: Can a subpanel lay flat on a shelf?

Jerry I am not following you in the least here.

Breakers can be mounted in any position, if the position is such that there is an up or down to the handle movement up must be the ON position.

With a breaker mounted in an enclosure on it's back there is no up position of the breaker handle.

240.81 Indicating.
Circuit breakers shall clearly indicate whether they are in the open ?off? or closed ?on? position.

Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the ?up? position of the handle shall be the ?on? position.
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I would say that a breaker in an enclosure on it's back is operating horizontally negating the up is ON requirement.

This is really no different then a typical breaker installation on a wall, the breaker handle action is left to right or right to left.

As far as enclosures listed and labeled for use with the panelboard section installed vertically in the horizontal enclosure I covered that with my reference to 110.3(B)
 
Re: Can a subpanel lay flat on a shelf?

Bob Badger said:
Jerry I am not following you in the least here.

Breakers can be mounted in any position, if the position is such that there is an up or down to the handle movement up must be the ON position.

With a breaker mounted in an enclosure on it's back there is no up position of the breaker handle.
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Bob,

Referring to "on the horizontal" as shown in Joe T.'s drawing above, versus "in the vertical" as shown in the same drawing.

When laid on its back, is that horizontal or vertical? Or is it just 'on its back'?

How about when installed on its back to the underside of a ceiling? Horizontal or vertical? Or just plain dumb? Would you want to remove a cover from a panel installed that way? Especially an FPE where the breakers tend to fall out on their own (no need to worry about a Zinsco, those breakers can't even be pried out is some cases, arced to the bus bars :) ).

Let's go into the 'installed on its back' enclosure a little.

Where and how do you measure the working space? The clearance to the floor and structural ceiling? What about heat dissipation in the enclosure? What about when the cover is removed and the enclosure is 'face up' what about objects falling into the live parts? When installed 'face down', what about live parts falling into you?

Those enclosures (for overcurrent devices) are designed and intended to be installed on walls or supports orienting the enclosure in the way a wall would. Now, 'vertical' and 'horizontal' make sense.

Right?

Once you start to consider the weird and unintended, it can really get weird.
 
Re: Can a subpanel lay flat on a shelf?

:eek:

zinsco2.jpg
 
Re: Can a subpanel lay flat on a shelf?

It seems 'impracticable' is a call for the local inspector to make.

I doubt when the CMP used the word horizontal they meant horizontal on it's back, but horizontal is horizontal.
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I wasn't aware that you had an inside track on what the CMP intended! Please share with us which CMP you are referring to and how you are privy to their intent.

Oh wait, maybe this is just a personal opinion...which carries absolutely no code wieght.
 
Re: Can a subpanel lay flat on a shelf?

Originally posted by jerry peck:
Let's go into the 'installed on its back' enclosure a little.

Where and how do you measure the working space? The clearance to the floor and structural ceiling?
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I agree and that is why I said the 110.26 requirements would be the issue that may prohibit this.


Originally posted by jerry peck:
What about heat dissipation in the enclosure? What about when the cover is removed and the enclosure is 'face up' what about objects falling into the live parts? When installed 'face down', what about live parts falling into you?
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All interesting questions none of which have a code reference.

Originally posted by jerry peck:
Those enclosures (for overcurrent devices) are designed and intended to be installed on walls or supports orienting the enclosure in the way a wall would. Now, 'vertical' and 'horizontal' make sense.
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Again this is 110.3(B) territory and I have said that may also be a section that could prohibit the installation.

The only thing I disagree with is the reference to 240.33 and 240.81.

I have had to mount enclosures on their side before as they where to tall to fit in the room. :p

[ September 04, 2004, 12:29 PM: Message edited by: iwire ]
 
Re: Can a subpanel lay flat on a shelf?

The only thing I disagree with is the reference to 240.33 and 240.81.
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Which part of 240.33 and 240.81 do you disagree with? Remember, I did not write those sections ( :D ) but maybe I can help read them. ;)

I have had to mount enclosures on their side before as they where to tall to fit in the room. :p [/QB]
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Then they should have done their planning properly and made the room larger. :cool:

Either way, 240.81 only concerns itself with which way the circuit breakers operate, not how the enclosure is installed, that is covered under 240.33 and 110.3(B).
 
Re: Can a subpanel lay flat on a shelf?

Originally posted by jerry peck:
Which part of 240.33 and 240.81 do you disagree with? Remember, I did not write those sections ( :D ) but maybe I can help read them. :D

[ September 04, 2004, 01:33 PM: Message edited by: iwire ]
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Re: Can a subpanel lay flat on a shelf?

240.33 clearly starts out with enclosures shall be installed in a vertical
 
Re: Can a subpanel lay flat on a shelf?

Hit add to soon.A vertical position,to me that means vertical up and down.240.81 says vertical also,I don`t think that the intent of the wording was to allow an enclosure to be mounted on it`s back face up.All to many reasons come to mind one if mounted on a plant shelf H2O is one ;)
 
Re: Can a subpanel lay flat on a shelf?

My opinion.
Impracticable,impracticle, physical protection, and severe physical protection need to be deleted from the NEC. As more and more people are 'studying' and trying to interpret the NEC, I do not believe some of the authors expected such scrutiny of the wording. They knew their intent and the wording sounded fine at the time (this is all conjecture on my part), but now that too much confusion, and misunderstanding has occurred, it is time for revision.

Or

Proper definitions located in the NEC need to be written.

The way I read this is the panel needs to be installed in the 'vertical'. But... there is some relief if impracticable - does that mean that poor planning can override common sense and safety?
 
Re: Can a subpanel lay flat on a shelf?

Depends on which way the breakers operate in the 'horizontally' installed panel.

If they operate with 'on' down, quite possibly nothing.

Notice that there IS only ONE ROW, not two rows, of breakers in that panelboard. Thus there is no reason to have 'on' up.
 
Re: Can a subpanel lay flat on a shelf?

If your out of room for mounting the panel on the wall how about putting it in the ceiling, as long as the ceiling isnt more than 6'6"? ;)
 
Re: Can a subpanel lay flat on a shelf?

It is up to you to draw your own conclusions about what the CMP (Code Making Panel) meant. However, I was there when this was discussed since I am on CMP-10. The discussion was about the panelboards being mounted either on their backs or on a ceiling and the consensus was that it was up to the AHJ for his interpretation. The CMP did not see a problem with that type of installation.

A proposal was not made to clean up the language and the panel did not wish to take the time to put together a panel proposal for this since it was not an issue. Therefore, the words have to stand by themselves. I assume that you are aware that the intent of the CMP means nothing after the revisions have been made, the Code has to stand on its own words. :D
 
Re: Can a subpanel lay flat on a shelf?

Here's a message I received from a person who has spent most of his life within the NEC Process:

Joe: New Panel members may not have the background, and may not take the time to research the background of a proposal, but one thing is certain - If you have a change in mind, keep at it - the Panel members change and in about three code cycles you will have a whole new bunch, and your proposal may get the nod.

It has happened to me.

On the other hand, the older Panel members should keep the newer members apprised of the background of a proposal, and the comment stage will certainly bring out any missteps by the Panel.
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Re: Can a subpanel lay flat on a shelf?

I also do not see any direct restriction in the NEC preventing a panel from being installed flat on its back.

I am curious if the UL standard for panels has any restrictions on installing a panel flat on its back, that would apply per 110.3(B) ... Seems like there may be a potential for moisture accumulation in that position for at least some of the panel types.
 
Re: Can a subpanel lay flat on a shelf?

Originally posted by jerry peck:
Notice that there IS only ONE ROW, not two rows, of breakers in that panelboard. Thus there is no reason to have 'on' up.
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Jerry,

240.81 says:
...Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the "up" position of the handle shall be the "on" position
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Bill
 
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