EC Magazine Article

Status
Not open for further replies.
infinity

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
by George W. Flach
Published: October 2007


Concrete-encased electrode

Q: Does the National Electrical Code (NEC) permit a grounding-electrode conductor smaller than 4 AWG copper for a concrete-encased electrode for a 60-ampere, 3-wire, 120/240-volt service? The service conductors are three 6 AWG copper with THWN insulation.

A: There is nothing in Article 250 that allows the grounding-electrode conductor to be smaller than 4 AWG copper. There also is nothing in Article 250 that requires the grounding-electrode conductor from the reinforcing steel to be larger than 4 AWG copper.

Article 250.66(B), which states the grounding electrode for a concrete-
encased electrode does not have to be larger than 4 AWG copper, covers the connection to the concrete-encased electrode.

Where the concrete slab in contact with the earth does not contain 20 feet or more of ?-inch or larger reinforcing rods, the concrete-encased electrode may consist of at least 20 feet of bare 4 AWG copper placed near the bottom of the concrete foundation. Article 250.52(A)(3) permits this substitution of wire for reinforcing rods. Notice the minimum size wire electrode is required to be 4 AWG bare copper
Click to expand...

I just got around to reading this issue of Oct.07 Electrical Contractor Magazine and wondered if everyone agrees with his answer?
 
iwire said:
So you use 4 AWG as the GEC for a 100 amp service? :-?
Click to expand...

I guess I missed that on 250.52(A)(3). I haven't done a 100 amp service in 20 years except for temp. poles. Here it is 200 or higher.

Seems to be a discrepancy doesn't it. I believe this is the explanation. My take on article 250.52(A)(3) is that if you use 20 feet of copper in the footing than it must be #4. I believe you can connect a smaller wire to that electrode if you have a smaller service.

It appears they want the #4 in case of future upgrades to the service. Maybe????? Just a guess.
 
Dennis Alwon said:
Seems to be a discrepancy doesn't it.
Click to expand...

Yes, but in my opinion only in EC&Ms response, not in the code.

I believe this is the explanation. My take on article 250.52(A)(3) is that if you use 20 feet of copper in the footing than it must be #4. I believe you can connect a smaller wire to that electrode if you have a smaller service.
Click to expand...

I agree, that is exactly what the code requires.

It appears they want the #4 in case of future upgrades to the service.
Click to expand...

The code does not require that, although I can not imagine using 4 AWG Bare CU and not bringing that out of the slab.

IMO EC&M has blown it again.
 
Article is here:
http://www.ecmag.com/index.cfm?fa=article&articleID=8085

2007.10_EC%20Cover.jpg
 
Q: Is a ?house? service and panel required for an entrance hall that is used for six apartments?

A: Yes, the electrical system must be arranged so that the common area of a multifamily dwelling is not supplied from an individual apartment panelboard. Article 210.25 reads, ?Common Area Branch Circuits. Branch circuits in dwelling units shall supply only loads within that dwelling unit or loads associated only with that dwelling unit. Branch circuits required for the purpose of lighting, central alarm, signal, communications, or other needs for public or common areas of a two-family or multi-family dwelling shall not be supplied from equipment that supplies an individual dwelling unit.?
Click to expand...

Where I am a two family with common hallways would not always get a 'house panel'

We would use fixtures in the hall with two sets of lamps, each set of lamp supplied from a unit.

Each person would be in control of the lamps they pay for.

Of course that was back in the 80s
 
iwire said:
IMO EC&M has blown it again.
Click to expand...

Do they ever print retractions/corrections to these sort of issues?


In the earlier part of this year, I picked up on a small issue with one of these questions. I emailed the author and recieved a reply sometime later that indicated a correction would be made in a future edition.
I haven't seen the correction in print refeenced back to that question.
 
iwire said:
.

IMO EC&M has blown it again.
Click to expand...


Not to slam EC&M, this article came from Electrical Contractor magazine.

My disagreement with the article is that a CEE made of 1/2" rebar or #4 CU can have a GEC sized according to 250.66 which allows GEC's smaller than #4.
 
Celtic, it may be time to quit holding your breath? :wink:


Roger
 
celtic said:
In the earlier part of this year, I picked up on a small issue with one of these questions. I emailed the author and recieved a reply sometime later that indicated a correction would be made in a future edition.
I haven't seen the correction in print refeenced back to that question.
Click to expand...


I checked to see if this were even possible and they don't even list a email address for the author of this article.
 
infinity said:
I checked to see if this were even possible and they don't even list a email address for the author of this article.
Click to expand...

They did provide his phone number at the bottom of Celtic's link.
 
infinity said:
I checked to see if this were even possible and they don't even list a email address for the author of this article.
Click to expand...

I emailed ECmag and had them fwd same to Mr. Flach.




********
Yes....let's NOT confuse ECmag with EC&M ....good catch there.
 
I agree....

The NEC states it shall not be required to be LARGER than 4 AWG CU to the CEE much like it says for ground rods for 6 AWG but we run 8 AWG Cu to ground rods on 100A panels....and so on.

The use of 250.66 is the method and except as permitted in 250.66(A) through (G)

Nice Catch.....;)

On the other issue bob bought up, I can see that if the common areas have lighting lets say for mailbox locations and so on or illumination for a common area it would not be allowed on the individual dwellings branch circuits....it I guess would all depend on the layout if their is a common area serving both individual dwelling areas such as lets say a light out front on a doorway leading to a common area....who pays for that light????
 
iwire said:
We would use fixtures in the hall with two sets of lamps, each set of lamp supplied from a unit.
Click to expand...
Couldn't there be an issue about disconnecting with this setup? What happens if only one occupant is available and needs to repair or replace the fixture?
 
LarryFine said:
Couldn't there be an issue about disconnecting with this setup? What happens if only one occupant is available and needs to repair or replace the fixture?
Click to expand...

The landlord owns the fixture and the EC fixing or repairing the fixture will be working for the landlord. The landlord has access.

I don't know if this is still being allowed but to me it was a better solution then requiring an entire panel, meter and separate bill for a couple of light fixtures. :)
 
iwire said:
The landlord owns the fixture and the EC fixing or repairing the fixture will be working for the landlord. The landlord has access.

I don't know if this is still being allowed but to me it was a better solution then requiring an entire panel, meter and separate bill for a couple of light fixtures. :)
Click to expand...

Wouldn't art 210.25(B) make it illegal. Some revision is made in 2008
 
Last edited:
Status
Not open for further replies.
Top