Ask Codeman!

Codes can be complicated and not always easy to understand. Luckily, we have access to the superhero of the Code World–"Codeman!" Codeman has answered countless questions over the years. "
Right now, Codeman needs to rest his eyes for a while, and he will answer your questions after a well-deserved break.

In the meantime, enjoy some of the past questions our caped codester has answered!

Grounding the Electrode System

Dear Codeman,

I am building a steel "Quonset hut" style building. My inspector says I have to have grounding inside the slab. He says this is per NEC code 250-50. Could you please explain what I need to do in order to meet code?

B.W.

Hi B.W.,

It sounds like your inspector is asking for a “concrete encased electrode.” These are required by the National Electrical Code, section 250.52(A)(3). These have been used west of the Rocky Mountains for many years, and are now required in your area as well. The 2005 National Electrical Code says that it is not necessary to break up the concrete on an existing building to make this connection, but on new buildings where you have access to the reinforcing steel in the slab, that steel should be connected to the grounding system.

These grounding electrodes are also known as “Ufer” grounds, in honor of the person who first developed the system, Herbert Ufer.

Of course, if you don’t have steel reinforcement in the slab, this isn’t an issue. If you do have steel reinforcement (and haven’t cast the concrete yet) you do need to connect that steel (or a substitute for it) to the grounding electrode system. You must connect to at least 20 feet of the encased steel. The connection can be made by running a #4 copper wire into the forms and connecting to the steel with a clamp that is rated for direct burial and encasement in concrete and for a rebar connection. You could also have a piece of the steel bent up through the top of the forms and make a connection above the slab. In both those instances, I am assuming that the different pieces of steel in the slab are bonded together via steel tie wires. What you do NOT want to do is bring a piece of steel out the side of the slab, because then it could rust. Another way of doing it is simply to lay 20 feet of #4 copper wire inside the slab, resting on chairs to keep it at least 2 inches above the soil.

®2008 Code Check

Below you'll find the actual text of the code. Please bear in mind this is 2005 code, which I think you are still using in Georgia. Also, if you look in our books you will see illustrations of various ways of making this “Ufer” ground, and you can also do a search for examples within our web site.

III. Grounding Electrode System and Grounding
Electrode Conductor
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.
Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete.

250.52(A)(3) Concrete-Encased Electrode.
An electrode encased
by at least 50 mm (2 in.) of concrete, located within and near the bottom of a concrete foundation or footing that is
in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other
electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (1⁄2 in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG. Reinforcing bars shall be permitted to be bonded together by the usual steel tie wires or other effective means.

Hope this helps,
Codeman!

A Common Question...
Codeman,
Can I run one common for two 20 amp circuits?

Thanks,
D.Z.

Dear D.Z.,

The National Electrical Code allows “multiwire circuits” for any of the 120-volt circuits required in article 210. These are sometimes known as Edison 3-wire circuits or common-neutral circuits.

It is very important that the ungrounded (hot) conductors originate from opposite poles, i.e., that they have voltage potential between them, and do not originate from the same bus. When installed correctly, the common or neutral carries only the imbalanced load difference. When originating from the same pole, the neutral would be carrying the sum of the loads, and could overheat. The NEC has required that these have a handle tie whenever the loads go to a common yoke (such as the top and bottom halves of a duplex receptacle with the connecting tab removed between the hots). That rule changed in the 2008 edition, which now requires a handle tie or single-handle common-trip breaker for all multiwire circuits.

The relevant sections of the NEC are found in 210.4 and in article 100 for the definition of “branch circuit, multiwire.”

Take care,.

Codeman!

ADA Codes
Dear Codeman,
Are there drawings, books, or flyer's pertaining to handicap, ADA codes? We need example heights of bathroom accessories, parking lots, ramps etc.

Thank you

XXX Construction Company

Hi XXX Construction Company,

There are many good illustrated guides to accessibility codes. Unfortunately, weI don’t write any of them. The International Code Council (ICC) publishes or distributes guides to the accessibility codes of several individual states. Their catalog is here:

http://www.iccsafe.org/e/prodcat.html?catid=AC&pcats=ICCSafe&stateInfo=luldblwxlTGPZaja4792|4

Another good resources is Builders Booksource in Berkeley, CA. Their on-line accessibility catalog is here:

http://www.buildersbooksource.com/cgi-bin/booksite/results_dev.html?searchfield=cat1%2ccat2%2ccat3%2ccat4%2ccat5%2ccat6%2ccat7%2ccat8&searchspec1=Accessibility%20Issues&room=1

The two books across the top of that site are nationwide, and the rest are for California..

Thank you.

Codeman!

©2008 Code Check

Reader Needs to Vent...
Dear Codeman,
I’m putting in drainage pipes for a new bathroom and need to know what is required for venting. Is there a certain distance from the first bathroom where vents need to be located before the drains dump into the main line? Could there be multiple fixtures dumping into the main line?

Thanks.

B.J.

.

Hi B.J..,

The basic purpose of venting is to maintain the seal on fixture traps. The water seal in the trap prevents entry of odors or vermin into the system. The vent should ideally be located at the end of the horizontal piece downstream of each trap seal.

Depending upon the area where you live and which code is adopted, you sometimes can have the vent located elsewhere. If a pipe functions as both a drain and a vent, it is known as a “wet vent” and the codes typically require that it be larger than the required size for a pipe that was only a drain. Some codes allow groups of fixtures within a bathroom, or groups of bathrooms, to be “wet vented” with horizontal wet vent pipes. Page 14 of our book “Code Check Plumbing” illustrates a horizontal wet vent.

I suggest you make a layout drawing of your project, showing where the fixtures are located and where the proposed drains and vents will be laid out, and take that drawing to your local building department. They should be able to give you further guidance on what your project will require.

Sincerely,
Codeman!

Which Code Check is Right for You?

Dear Codeman,

Can you tell me the diference between Code Check Complete, and Code Check 5th edition?

N.P.

Hi N.P.,

Code Check 5th edition is in our original flip-chart format, with four sections (building, plumbing, mechanical, and electrical). It is 30 pages, and it is laminated and designed to withstand a cup of coffee spilled on it as well as getting tossed around in the cab of a pickup truck.

We also have longer flip-chart books of all four major disciplines – separate 30 page books on building, plumbing, mechanical, and electrical. These go into more detail than Code Check 5th edition.

Code Check Complete is a compilation of those 4 other books, bound together inside hard covers, even though maintaining flip-chart form inside. Since the book is only 6 inches by 9 inches, it takes twice as many pages as the 8 1/2 x 11 flip charts, so Code Check Complete is 240 pages total.

Simple summary: 5th edition is for field use. Complete is for office use.

Codeman!

Egress Windows

Codeman,

Hi, I have a question about egress windows.

Would a double hung replacement window that meets the height from the floor requirement and the width requirement meet the egress requirement if, to get the required opening height, the sashes needed to be tilted in and lifted out? (no tools required)

.
T.M.

Dear T.M.,

It’s my understanding that when these tilt-out double-hung windows first came on the market, the purpose of that feature was to comply with the rules for escape and rescue. However, some of us who are not the most mechanically inclined folks still find these a challenge.

I believe it is a question that could be interpreted different ways by the local officials, and therefore I would urge you to check with them before ordering or installing such windows in a location where escape and rescue openings are required. If I was the building official, I would allow them, but my opinion carries no weight in your jurisdiction.

Thank you,

Codeman!

Room to Move

Dear Codeman,

I was just wondering if there is a code requirement that describes minimum clearance from a toilet fixture to say a countertop or shower.

Thanks-.

J.H.

Hi CG,

There is indeed such a requirement in some of the codes. The 2006 International Residential Code section 307.1 requires the clearances in the following illustration, which means a minimum of 4 inches to a vanity. It’s not so clear what the distance is from a toilet to a tub or shower, other than the illustration showing the centerline of the toilet being 15 inches from the tub. There is also a rule in section 2705.1 item #5 which states “The centerline of water closets or bidets shall not be less than 15 inches (381 mm) from adjacent walls or partitions or not less than 15 inches (381 mm)from the centerline of a bidet to the outermost rim of an adjacent water closet. There shall be at least 21 inches (533 mm) clearance in front of the water closet, bidet or lavatory to any wall, fixture or door.”

We have our own version of this, shown in figures 76 & 77 below of Code Check Plumbing 3rd edition.

Thank you.

Codeman!

Holy Joists!

Dear Codeman,

I would like to know about putting holes in my basement floor joists for running my electical wiring through. How big can they be? How far apart do they have to be? How many wires can I run through (1) hole?

Thank You,.

T.S.

Hi T.S.,

The electrical code will tell you when you need to drill holes for wires, and the building code tells you how and where to bore the holes.

Large cables, conduits, and electrical tubing are allowed to be simply attached to the bottoms of the joists or on a backing strip. Small cables (anything less than 8/3) must be through the bored holes or on a running strip. You can always install the wiring in bored holes – the NEC only restricts the wiring size and materials for what can be run on the bottom of the joists. See NEC 334.15(C) and 300.4.

The NEC requires holes to be at least 1 1/4 inches from the surface for cable systems (300.4) or to have metal plates protecting the cables. However, the building code is typically more restrictive. Holes must generally be at least two inches from the bottom of the joist and two inches from each other. The maximum size is 1/3 the joist depth. The following illustration from Code Check Building 2nd Edition shows these rules:

©2007 Code Check

Good luck,

Codeman!

How Does Your Duplex Outlet Hang?

Dear Codeman,

When mounting a duplex outlet does the grounding hole go up or does it go towards
the floor?

RC

Hi RC,

It can go either way - the codes do not specify a particular orientation.

In residential construction, it is a common practice to install switched "half-hot" receptacles with the ground hole up, and to install the others down. That serves to identify which receptacle is controlled by the light switch.

Many electricians prefer to install the ground hole up in industrial or commercial applications. The reasoning is that something landing on the cord near the outlet will strike the grounding conductor first, rather than an ungrounded conductor.

Codeman