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Concrete encased electrodes. #59395
12/03/05 03:31 PM
12/03/05 03:31 PM
A
Alan Nadon  Offline OP
Member
Joined: Mar 2005
Posts: 399
Elkhart, IN. USA
I have a question for anyone that works in an area where the rebar is used for grounding. We will have to start using this with the 2005 NEC.

How do you make the connection ?

The IRC sec 404.4.6.1 requires all rebar to be encased in concrete.
Does an electrician make this connection before the pour or is the foundation trade trusted to make up the connection and leave a #4, or larger if over 200 amp. service sticking out of the cement.
It is assumed [big problem there] that the foundation inspector will see the GEC when he inspects before they pour.
How does the foundation guy know what size service is going to be installed ?

If this kind of grounding electrode is normally used in your area or if you inspect for it please let me know how you do it.
Alan--Inspector


Alan--
If it was easy, anyone could do it.
Work Gear for Electricians and the Trades
Re: Concrete encased electrodes. #59396
12/03/05 03:51 PM
12/03/05 03:51 PM
I
iwire  Offline
Moderator
Joined: Jan 2003
Posts: 4,391
North Attleboro, MA USA
Here in MA an electrical permit must be obtained, an electrician must make the connection, and finally an electrical inspection before the pour.

In other States the rebar installers turn up a section of rebar that the electrician hooks onto later.

We have always cad welded the conductor to the rebar but mechanical fasteners are available.

By the way the GEC to a concrete encased electrode is never required by the NEC to be larger than 4 AWG and can be smaller. It could be 8 AWG CU for a 100 amp service.


Bob Badger
Construction & Maintenance Electrician
Massachusetts
Re: Concrete encased electrodes. #59397
12/03/05 07:45 PM
12/03/05 07:45 PM
E
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
Same here, permit, electrical inspection then pour.

Ufer is required for any foundation work of 20' in length by local code.
Quote
A concrete-encased electrode as defined by Section 250-50(c) shall be installed at each new building or structure, and for existing buildings or structures when a new or replacement foundation footing with a perimeter length of 20 feet (6.096 m)is installed.


And yep, often the electrician is responcable for install and inspection. A GC can pull the permit and install, but must get the Electrical Inspector out. Many will opt for the electrician to do it, cause they don't want to be hassled on the inspection if they mess it up. Wrong connections, or one guy who installed insulated wire... Then have to hold up a pour. Some have made the mistake of not doing a Ufer at all, and had to break out the demo hammer... It is actually nice because this little bit of work early in projects kinda locks you in for the rest of it. Usually we do a wire electrode rather than rebar, cause we have had concrete workers cut or re-arrange the rebar after we're gone. If the see the wire, they tend to leave it alone. And seeing that often the area where the wire would exit the foundation is often in a finish wall, we just use a long enough wire to go all the way to the equipment later. So there is no connection to made.


Mark Heller
"Well - I oughta....." -Jackie Gleason
Re: Concrete encased electrodes. #59398
12/04/05 12:02 PM
12/04/05 12:02 PM
A
Alan Nadon  Offline OP
Member
Joined: Mar 2005
Posts: 399
Elkhart, IN. USA
Thanks for the input.
I was looking at 250.52 not smaller than # 4 AWG instead of 250.66(B) not required to be larger than #4.
I can forsee a lot of complaining and some confusion before this starts to run smoothly in areas that haven't done it before.

What is the typical length or wire that is used ?
Allowing 20 feet in the foundation or connected to the rebar, then how much to make it accessable ?
Alan--


Alan--
If it was easy, anyone could do it.
Re: Concrete encased electrodes. #59399
12/04/05 01:46 PM
12/04/05 01:46 PM
E
e57  Offline
Member
Joined: May 2003
Posts: 2,876
S.F.,CA USA
20' of length 2" from bottom of the foundation, then whatever length to the top of foundation, plus whatever comfortable length needed to make a connection. Personal experiance says more is better. If the foundation is right under, or close to where the panel will be, long enough to make it to the panel. If longer distance away, (like other side of building) I leave a few feet, to insure at least some portion to be made accessible. If not the whole distance. But sometimes the whole length can be an obstical....

BTW when they started requiring it here, there was some confusion early, but was quickly dispelled after the fist few, and people got comfortable with it.


Mark Heller
"Well - I oughta....." -Jackie Gleason

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