Detached Addition Subpanel

A.W.Davis

Okay guys, all of you have been most helpfull with my questions in the past.....hell if you lived close to me I'd buy you a beer just for saving my insanity.

Heres my question, can I have a Nema type 3 subpanel on the exterior of the house with more than 6 breakers, the homeowners wants the subpanel located outside of their new detached addition and I am estimating roughly 10 breakers for the new addition........I recall reading in my N.E.C that you cant have more than 6 tied breakers(?) on a exterior panel......now is that for a service panel or for any panels located outside?

Thanks,Anthony

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A.W. Davis Construction Co.
http://www.awdavisconstruction.com/
Your friendly remodeling contractor

mdshunk

Without going into the code very much, you summarily can't have any more than 6 moves of the hand to kill the power to each structure. Since this addition seems to be detached, that rule will now apply again to this seperate structure. It appears that you'll need a main in that panel, to comply with the 6 move of the hand rule. Shouldn't really be a big deal, unless you already bought the wrong panel.

A.W.Davis

Excellent,
I havent purchased the subpanels yet....still waiting the others subs to pour the foundation and frame everything,then I can do my thang!
I guess I will have a main outside and another subpanel for all my circuits inside.

Thanks for the info mdshunk

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A.W. Davis Construction Co.
http://www.awdavisconstruction.com/
Your friendly remodeling contractor

mdshunk

Yep, that will work too. If you put a main only outside, there will be no need for a main in the indoor mounted subpanel. You can use a main lug panel inside, in that case, as you already have less than six moves of the hand to kill the power to that structure provided by that outdoor main. Do you typically do your own wiring? Or do you just mount the major equipment and let the sparky take it from there? I don't care one way or the other, but it is interesting to learn how other people do things.

A.W.Davis

Yeah I do normally wire all of my kitchens and bathrooms from start to finish, it works out well because I know exactly where to place all of my electrical.

Ohh and because almost all of my jobs are remodels, the placement of the service and subpanels for new construction is kinda a new process......I hate admitting that openly, but its probably obvious anyways.

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A.W. Davis Construction Co.
http://www.awdavisconstruction.com/
Your friendly remodeling contractor

Sparky Joe

You better get a "ufer ground" in that pour, that is required as of the 2005 code

RobertWilber

Why?
Where is that required?

A.W.Davis

I planned on having one just to be safe.

I spoke with the framing contractor, they are going to turn a 20' piece of rebar up for me to tie into when everything is framed.

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http://www.awdavisconstruction.com/
Your friendly remodeling contractor

Teetorbilt

I'm planning on running power to my shed. My sparky said that I need a disconnect at the house. This could be a local storm code.

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Sparky Joe

I believe the change states that "where it is available" therefore with any brand new building a ufer is required. And the exact name is "concrete encased electrode" meaning if there is rebar (or any electrode) being poured in concrete then it has to be bonded, as well as building steel (if available), and cold water pipe (if available). Obvously on an old building a concrete encased electrode would not be available, hence the term encased, although a water pipe (within 5 feet of entrance) and building steel will always be available.

Does that answer your question Robert?
Also to point out to you that this new change is a relief because pounding ground rods is a thing of the past. Unless of course there is already one pounded and it is available.

I could do the dirty work and find the exact refference for you if you like, other than that it is in the 2005 code (the red one)

RobertWilber

yep
that's what I want
the exact reference

also, according to a description of the UFER concept [which someone here provided a link to a few threads ago] you aren't supposed to put the copper/steel joint in the pour because it doesn't last. There is supposed to be an exposed accessible junction outside the concrete.

anyway, I don't know why you say that ground rods are a thing of the past ... they don't use rebar in small housing foundation pours and I don't believe that the 8-gauge sheet screen used in some floor pours constitutes a Ufer grid

mdshunk

That Ufer code says "where available". If the footer is already done by the time the electrician is called, the footer rebar is no longer available. Simple as that.

Sparky Joe

I think what defines it is if the concrete was poured when the permits were pulled regardless of when they hired an electrician. I guess you could argue the interpretation, in the end it's up to the AHJ.
Our inspector(an old union hand) would never allow the ufer to be missed.

Oh and they make a UL listed ground bar clamp specifically for the purpose(looks like a water pipe clamp but smaller) (read 250.68 (A) exception no. 1). If the bond is exposed then I believe it needs to be cadwelded or by some other irreversible means (250.64 (C) (1)).
You know, this grounding stuff is not just some silly game we play, it's very important in every electrical system(even an ungrounded one), you really ought to know it.

250.52 (A) (3)

and no, chicken wire is not required

mdshunk

That's a good inspector, then. In our area, the foundation contractor would need to turn up a rebar out of the pour. If he connected a #4 to the rebar, he'd need have an electrician do that. Since they don't normally have electricians on foundation jobs, and we're never even called until the place is under roof (if no other underslab work), they just turn up a rebar for us to bond on to. If they don't, and the inspector misses it, then the ufer is not available.

RobertWilber

kid, I was an IBEW foreman before you were in diapers

Sparky Joe

Didn't they require you to buy a code book back then?

RobertWilber

Interestingly enough, the oldest code book that I own, and which was purchased while in the trade, is 7 years older than you are.
On the other hand, has anyone ever before suggested you read any books related to manners and etiquette? There was a book written in the early 20th century called "How to Make Friends and Influence People." Though not about etiquette, you might find it worth the investment of your time.
There is also one written some 2000 years earlier that might be worthy of your inspection. Seeing as you are from Salt Lake, it should be easy to find a copy.

and, by the way, it is the rule that it doesn't have to be accessible IF cadwelded, otherwise it MUST be

Speedy Petey

250.50 Grounding Electrode System
All grounding electrodes as described in 250.52(A)(1) through (A)(6) that are present at each building or structure served shall be bonded together to form the grounding electrode system. Where none of these grounding electrodes exist, one or more of the grounding electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.


The Ufer rule for new construction is if there is any rebar present it must be used as an electrode. The words "that are present" were changed from "if available". If the rebar is present, hidden or not, it must be used. Period. A hard ass inspector will make you expose the rebar if it was not left exposed before the pour.

Here is the Handbook commentary:

This section was revised for the 2005 Code to clearly require the inclusion of a concrete-encased electrode, described in 250.52(A)(3), in the grounding electrode system for buildings or structures having a concrete footing or foundation with not less than 20 ft of surface area in direct contact with the earth. This requirement applies to all buildings and structures with a foundation and/or footing having 20 ft or more of 1/ 2 in. or greater electrically conductive reinforcing steel or 20 ft or more of bare copper not smaller than 4 AWG. However, an exception does exempt existing buildings and structures where access to the concrete-encased electrode would involve some type of demolition or similar activity that would disturb the existing construction. Because the installation of the footings and foundation is one of the first elements of a construction project and in most cases has long been completed by the time the electric service is installed, this revised text necessitates an awareness and coordinated effort on the part of designers and the construction trades in making sure that the concrete-encased electrode is incorporated into the grounding electrode system.

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Speedy Petey

I'm not sure where you guys are finding this cadweld or irreversible clamp requirement...

250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes
The grounding or bonding conductor shall be connected to the grounding electrode by exothermic welding, listed lugs, listed pressure connectors, listed clamps, or other listed means. Connections depending on solder shall not be used. Ground clamps shall be listed for the materials of the grounding electrode and the grounding electrode conductor and, where used on pipe, rod, or other buried electrodes, shall also be listed for direct soil burial or concrete encasement. Not more than one conductor shall be connected to the grounding electrode by a single clamp or fitting unless the clamp or fitting is listed for multiple conductors. One of the following methods shall be used:
(1) A pipe fitting, pipe plug, or other approved device screwed into a pipe or pipe fitting
(2) A listed bolted clamp of cast bronze or brass, or plain or malleable iron
(3) For indoor telecommunications purposes only, a listed sheet metal strap-type ground clamp having a rigid metal base that seats on the electrode and having a strap of such material and dimensions that it is not likely to stretch during or after installation
(4) An equally substantial approved means

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Sparky Joe

Sorry if I touched a nerve Rob, your usually the one always poking the jokes. Around here they only read the 'Book of Mormon', which I have not read nor the other mentioned, but I have read and hold dearly my KJV 1611 bible.

My refferences;
250.70 says the bond can be a clamp as long as it's listed to be a clamp, and can be encased in concrete if it is listed for that purpose.

250.70 Methods of Grounding and Bonding Conductor Connection to Electrodes
The grounding or bonding conductor shall be connected to the grounding electrode by
exothermic welding, listed lugs, listed pressure connectors, listed clamps, or other listed
means. Connections depending on solder shall not be used. Ground clamps shall be listed
for the materials of the grounding electrode and the grounding electrode conductor and,
where used on pipe, rod, or other buried electrodes, shall also be listed for direct soil
burial or concrete encasement. Not more than one conductor shall be connected to the
grounding electrode by a single clamp or fitting unless the clamp or fitting is listed for
multiple conductors. One of the following methods shall be used:
(1) A pipe fitting, pipe plug, or other approved device screwed into a pipe or pipe
fitting
(2) A listed bolted clamp of cast bronze or brass, or plain or malleable iron
(3) For indoor telecommunications purposes only, a listed sheet metal strap-type
ground clamp having a rigid metal base that seats on the electrode and having a
strap of such material and dimensions that it is not likely to stretch during or after
installation
(4) An equally substantial approved means


And 250.68(A) exception 1, says that a concrete encased electrode does not need to be accesible.

250.68 Grounding Electrode Conductor and Bonding Jumper Connection to
Grounding Electrodes
(A) Accessibility The connection of a grounding electrode conductor or bonding jumper
to a grounding electrode shall be accessible.
Exception No. 1: An encased or buried connection to a concrete-encased, driven, or
buried grounding electrode shall not be required to be accessible.
Exception No. 2: An exothermic or irreversible compression connection to fire-proofed
structural metal shall not be required to be accessible.
from the handbookWhere the exposed portion of an encased, driven, or buried electrode is used for the
termination of a grounding electrode conductor, the terminations must be accessible.
However, if the connection is buried or encased, terminations are not required to be
accessible. Ground clamps and other connectors suitable for use where buried in earth
or embedded in concrete must be listed for such use, either by a marking on the
connector or by a tag attached to the connector. See Exhibit 250.22 and Exhibit 250.24