250.50

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Re: 250.50

Brent I am not sure what you mean.

A house may never have a water supply that would quilfy as a grounding electrode.

If the house is supplied by a plastic water main then 250.52(A)(1)s Metal Underground Water Pipe is not available.

If the NFPA did not put the words "If available on the premises at each building or structure served" you would not be able to feed a building where some of these are unavailable.

How many wood frame houses have 250.52(A)(2)s "Metal Frame of the Building or Structure" to conect to.
 
Re: 250.50

iwire,

Most wood framed houses have concrete footings. Most wood framed houses can have ground rings installed.
 
Re: 250.50

A ground rod, for example, is never available until you pound it into the dirt. A ground ring is never available until until you dig a trench and drop some wire into it.

[ May 20, 2004, 11:02 PM: Message edited by: ryan_618 ]
 
Re: 250.50

This may help....
Formal Interpretation 78-4
Reference: Article 250.50
Question: Is it the intent of 250.50 that reinforcing steel, if used in a building footing, must be made available for grounding?
Answer: No.
Issue Edition: 1978
Reference: 250-81
Issue Date: March 1980
Click to expand...
 
Re: 250.50

Originally posted by brentp:
iwire,

Most wood framed houses have concrete footings. Most wood framed houses can have ground rings installed.
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Yes they can have these used or installed but are not required to.

Some areas do force the use of the footing ground even though that is not the intent of the NFPA as evidenced by the formal interpretation Web Sparky referenced.

250.50 Grounding Electrode System.
If available on the premises at each building or structure served, each item in 250.52(A)(1) through (A)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes are available, one or more of the electrodes specified in 250.52(A)(4) through (A)(7) shall be installed and used.
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Notice the last sentence in this section, all that is required is one of the electrodes.

You do not have to install all of them.

What is it that is bothering you about this?

I am not saying grounding electrodes are not important but the integrity of the grounded conductor back to the source (the power company transformer) is much more important for safety at the voltages used in structures then additional grounding electrodes.

Ask a specific question and I am sure the members here can answer it. :)

[ May 21, 2004, 05:03 AM: Message edited by: iwire ]
 
Re: 250.50

Thanks guys. I'm out of my state of confusion and I am now perfectly clear on the Code requirements. :)

The engineer on my current project is requiring extensive grounding. In my attempt to make sense of it, I was reading things into the Code that just simply aren't there.

I think I'll just continue with my Code study and leave the engineering to others. :D

Brent
 
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