glass house receptacles

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alankoch

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I just got out of plan check for a house we designed that is 100% floor to ceiling glass walls at the perimeter with prefab cabinets as room dividers. We just noticed the plan check engineer added numerous receptacle outlets all along the perimeter with a note "no point at floor along glass wall greater than 6' from receptacle with receptacles no more than 18" from glass wall". My interpretation of the code does not lead to this conclusion! As far as I can tell, if we do not have "usable wall space" then outlets are up to our own discretion. Where we have usable wall space, we will follow the 6' distance to outlet rule. Is this correct?

(in our original design we placed floor outlets strategically so that there is never any point in any room that a person is farther than 6' from a floor receptacle outlet - this often means however that a floor outlet is farther away from the glass walls than 18")
 
If the glass panels are fixed they count as wall space and receptacle spacing must not exceed the dimensions outlined in Article 210. Floor receptacles mounted up to 18" from the glass will satisfy the spacing requirement.
 
alankoch said:
.......(in our original design we placed floor outlets strategically so that there is never any point in any room that a person is farther than 6' from a floor receptacle outlet - this often means however that a floor outlet is farther away from the glass walls than 18")
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Alan

Do you understand the spacing rule correctly? 210.52(A) references wall spaces, not any space in the room. Your post makes me think you attempted to scatter receptacles all across the floor, when code requires you to measure along the wall only.

Jim T
 
"usable wall"

"usable wall"

Can anyone define what "usable wall" means? What is the intent of the code in terms of placing receptacles? I found this in a code digest:

"Usable wall space" is defined as any wall space 2' or more in width, not to include doorways, areas
occupied by a door when fully opened, windows which extend to
the floor, fireplaces or other permanent installations that
would limit the use of the wall space.

Here the code seems to be saying that the placement of outlets - in terms of walls - has to do with "the use of the wall space". I would argue that a glass wall (floor to ceiling window) severely limits the use of the wall space. If I don't have proper walls, why would I not place the outlets on the floor where they make sense in terms of a furniture plan? - Or is the earlier comment (here I paraphrase) "fixed window = wall" correct?
 
more "usable wall"

more "usable wall"

Sorry, I just read my post and thought I should include the section that led me to look at the definition of "usable wall"

2. Except as otherwise required, receptacles shall be installed
in the finished walls of every room or area, other than
kitchens, bathrooms, hallways, laundry rooms, utility rooms or
closets, so that no point along the floor line of any usable
wall space is more than (6') horizontally from a
receptacle in that or an adjoining space, such distance being
measured along the floor line of the wall spaces involved.
 
210.52(A) General Provisions. In every kitchen, family room, dining room, living room, parlor, library, den, sunroom, bedroom, recreation room, or similar room or area of dwelling units, receptacle outlets shall be installed in accordance with the general provisions specified in 210.52(A)(1) through (A)(3).
(1) Spacing. Receptacles shall be installed so that no point measured horizontally along the floor line in any wall space is more than 1.8 m (6 ft) from a receptacle outlet.
(2) Wall Space. As used in this section, a wall space shall include the following:
(1) Any space 600 mm (2 ft) or more in width (including space measured around corners) and unbroken along the floor line by doorways, fireplaces, and similar openings
(2) The space occupied by fixed panels in exterior walls, excluding sliding panels
(3) The space afforded by fixed room dividers such as freestanding bar-type counters or railings
(3) Floor Receptacles. Receptacle outlets in floors shall not be counted as part of the required number of receptacle outlets unless located within 450 mm (18 in.) of the wall.
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A fixed glass panel or window will count as wall space. If it counts as wall the above spacing requirements apply. You may use floor receptacles spaced along the windows within 18" of where the window meets the floor to satisfy the requirement. Simply placing the receptacles where they may be needed will not comply with the NEC. As you can see in the first sentence, you could have a sunroom constructed entirely of glass and the spacing requirement for receptacles would still apply.
 
You are lacking a background in nec and wiring.Suggest you take some courses.For now your solution is easy.Use floor boxes within 18 inches of wall.Follow the min. requirements and if need be add extras.You dont want cords to be running where people walk.I think we all would like to see somepictures of this home.

How do the walls meet insulation codes ?
 
Jim, I think you might have been a bit hard on Alan with the "courses" comment. This doesn't sound like someone utterly unfamiliar with the code, just not as exceedingly familiar with it as other people. :)

I agree with Trevor's review of the section. The floor receptacles are required to be within 18" of the perimeter of the glass building. Floor receptacles aren't going to block the view - appliances might. It's better to have the code-required receptacles there, unused but available, than force someone to use an extension cord later on.

I too would love some pictures. :)
 
alankoch said:
Can anyone define what "usable wall" means? What is the intent of the code in terms of placing receptacles? I found this in a code digest:

"Usable wall space" is defined as any wall space 2' or more in width, not to include doorways, areas
occupied by a door when fully opened, windows which extend to
the floor, fireplaces or other permanent installations that
would limit the use of the wall space.

Here the code seems to be saying that the placement of outlets - in terms of walls - has to do with "the use of the wall space". I would argue that a glass wall (floor to ceiling window) severely limits the use of the wall space. If I don't have proper walls, why would I not place the outlets on the floor where they make sense in terms of a furniture plan? - Or is the earlier comment (here I paraphrase) "fixed window = wall" correct?
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In the 2005 NEC handbook it states, "The word usable does not appear at all in 210.52 as a condition for determining compliance with the receptacle spacing requirements. As an example, to correctly determine the dimension of the wall line in a room, the wall space behind the swing of a door is included in the measurement. This does not mean that the receptacle outlet has to be located in that space, only that the space has been included in the wall line measurement."

I don't know what code was being used when you found the word useable or that did not include the area behind the door swing. Floor outlets along the glass walls would absolutely be required by the NEC.
 
In lieu of a floor box I have also put wiremold at the base of the window or you could have the storefront manufacturer (if that is what is being used) leave enough space at the base of the window so that the receptacles can be installed at that level. I have done each of these items for residential high rise construction that wanted glass all along one wall.
-Ed
 
thank you

thank you

thanks everyone - it has been very instructive. I am an architect, not a contractor or design engineer therefore my depth in any particular code area is fairly shallow since there are so many codes I need to consider. Also, I recently relocated from NYC where the code was quite different in many respects.

As for the insulation query, it is fairly complicated to discuss the Title 24 reqs as they relate to a glass house (could be a long thread in itself) but suffice it to say that R13 min is required in "walls", but because we have only glass... etc. You can see why I was thinking along these lines in terms of the outlets... On the other hand, we do have underslab insulation as well as R30 on the roof. We also have extremely efficient equipment and use radiant heat which doesn't have to heat the air space of the rooms to feel comfortable.

For anyone curious of what this house looks like, I invite you to visit our website; the house is a prefab design (site built with prefab components) we are building in 4 locations currently. www.tkithouse.com or look at our construction blog for the nearly complete prototype house (built into a hillside -- and therefore using conventional walls in addition to the expanses of glass); www.tk-ithouse.blogspot.com.

thank you all again for lending your expertise.
 
Sure nuff, it's a glass house. :D

My wife would kill for that house. She's a window freak. :)

Thanks for the links, and good luck in your pursuits. :)
 
I agree that the code requires that the fixed glass is a wall, that outlets can be put in the floor no more than 18 inches from the wall, spaced every 12 ft. You can however install more outlets than that if you think that would be a good installation for your customer (like in the middle of the room).

However, if you think you have a unique situation or a better plan, don't be afraid to contact the electrical inspector who will be inspecting this. He may agree with you or show you something better yet. Either way you'll get the definitive answer and know what to design and expect-no guessing.

I don't understand why more of us don't just ask the inspector what he is going to require-MOST of them are reasonable and good people.

Joe
 
georgestolz said:
Jim, I think you might have been a bit hard on Alan with the "courses" comment. This doesn't sound like someone utterly unfamiliar with the code, just not as exceedingly familiar with it as other people. :)

I agree with Trevor's review of the section. The floor receptacles are required to be within 18" of the perimeter of the glass building. Floor receptacles aren't going to block the view - appliances might. It's better to have the code-required receptacles there, unused but available, than force someone to use an extension cord later on.

I too would love some pictures. :)
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Sorry if it came out that way.I think it would help him and give him an edge over the rest.Some time working in field would help many to understand whats involved.

I do see one major problem in that a few kids with rocks could destroy one of these.Personally i love dark rooms.My bed room window has all the sun removed by way of cardboard.Its the only way i can sleep in on sat and sun.
 
Jim W in Tampa said:
Sorry if it came out that way.I think it would help him and give him an edge over the rest.Some time working in field would help many to understand whats involved.

I do see one major problem in that a few kids with rocks could destroy one of these.Personally i love dark rooms.My bed room window has all the sun removed by way of cardboard.Its the only way i can sleep in on sat and sun.
Click to expand...
It looks like the guy designing these has an "EDGE" over you Jim. Maybe you should work in the office a little to help you understand.

I like the house, Can I get one ordered in a multi level?
What about Central A/V ducting?

But while placing the receptacles for the original owner/buyers floorplan, it may not meet requirements for the next owner or owner after that. This is one reason the NEC has these requirements.
 
jshaw said:
In the 2005 NEC handbook it states, "The word usable does not appear at all in 210.52 as a condition for determining compliance with the receptacle spacing requirements. As an example, to correctly determine the dimension of the wall line in a room, the wall space behind the swing of a door is included in the measurement. This does not mean that the receptacle outlet has to be located in that space, only that the space has been included in the wall line measurement."

I don't know what code was being used when you found the word useable or that did not include the area behind the door swing. Floor outlets along the glass walls would absolutely be required by the NEC.
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That begs to ask the question on a bedrooms layout...if the room as a doorway to it and then 3-4 feet of hallway before it actually opens into the room itself.....are receptacles required in that space....regardless of being behind a door.......is that considered "HallWay" since it is no usuable space.....what ya think...
 
Radio, I count that space in my layout. Generally, receptacles end up just outside that would-be "hallway" when applying the 6' rule from the doorjamb.
 
I found this interesting because the space is considered unusable and in many cases it is like a 3' walkway once you enter the room itself....and only as wide as the actual doorway....so what I see alot around here and it seems to go over with the local AHJ's is that it is considered HallWay until it actually opens into the room.....to which time the 6' rule would then begin to apply.

I personally just lay it out in all cases....but I heard one local AHJ say they dont like them in the small hallway because it temps items to be placed in that area and it is only in most cases as wide as the door itself.

Found it quite interesting.......

5. "Usable wall space" is defined as any wall space 900mm (3',
NEC 2') or more in width, not to include doorways, areas
occupied by a door when fully opened, windows which extend to
the floor, fireplaces or other permanent installations that
would limit the use of the wall space.
 
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Where in nec does it say USABLE wall space ? Behind that door is wall space,usable depends on what your pluging in.Had inspector tell be that it might be the only easy to get at receptacle for the vac. or how about nightlight.Very usable to me and i would require it to meet code.
 
lol...guess it all depends on the inspector....like i said had more than one say it is hallway as it is not usable as the same space as the actual bedroom because it is too narrow and occupied by the door swing.

Oh....naw...the unusable space I believe was from another person understanding of it.....but the NEC only defines what is considered wall space...and I do not believe it says anything actually about the door swing area...

Just found it online and thought it was interesting to post.

But I was more talking about the space in some bedrooms when you walk in...and their is a kinda hallway portion that is 3-4' long before it actually opens up into the room...and that space is usually only as wide as the doorway....this is what some AHJ's around here still consider a hallway...since they dont want anything plugged or within it.....it can effect egress and so on......was their reasoning...but to all their own...

Personally I think it would be great to have the newest NEC clarrify.....wall space a little better.....but hey thats me....i always count from the door opening anyway.....so I usually have the 6' covered...lol
 
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