Grounding the foundation rerod?

[Duffster]

So I am pouring a new foundation and find out I need to attach a ground wire to the rerod in the concrete walls. What is the theory behind this?

 

[buckeyefarmer]

The Ufer Ground

It makes a good ground better.

 

[framer]

Been around enforced by inspectors about 5 years now.Uses rebar as ground
wire.I do know now around here we have chiseled out concrete to find rebar
then weld a piece of rebar to it for electricians.

 

[dmccarty]

I wish I knew about this when we built the house.....

Later,
Dan

 

[69x11]

So I am pouring a new foundation and find out I need to attach a ground wire to the rerod in the concrete walls. What is the theory behind this?

is the house already grounded thru and electrode encased in concrete? If not there is no need to do this, it actually creates a parallel grounding issue, if the home is grounded thru a normal driven or buried electrode, then the new grounding would run back to existing service grounding (ie the rod) if the electrode is encased in concrete..ie the rebar, then the new grounding would need to attach to it. check out 2008 nec article 250. dang i cant remember...stand by

 

[69x11]

250.52 Grounding Electrodes.
(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 (ｽ 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.


Used as a Grounding Electrode Conductor

"250.66 Size of Alternating-Current Grounding Electrode Conductor.
(B) Connections to Concrete-Encased Electrodes.
Where the grounding electrode conductor is connected to a concrete-encased electrode as permitted in 250.52(A)(3), that portion of the conductor that is the sole connection to the grounding electrode shall not be required to be larger than 4 AWG copper wire.

 

[Duffster]

is the house already grounded thru and electrode encased in concrete? If not there is no need to do this, it actually creates a parallel grounding issue, if the home is grounded thru a normal driven or buried electrode, then the new grounding would run back to existing service grounding (ie the rod) if the electrode is encased in concrete..ie the rebar, then the new grounding would need to attach to it. check out 2008 nec article 250. dang i cant remember...stand by

I am not sure if I am following ya.

Right now there isn't a house or electrical service. Is the rebar ground done in lieu of the old (2 copper rods) way of grounding or is both supposed to be done?

Another thing. When grounding rebar in dairy barns for stray voltage the bar is all welded together but in the house it could be tied together. I don't see how the tied bar can be a good enough conductor.

 

[rjkobbeman]

If I am following this correctly, it sounds like you want to either ground the service through a properly-grounded-rebar ("foundation" ground) OR use the traditional copper rod driven down in the earth... but not both.

If you do both you can have potential between the two grounds.

 

[Duffster]

If I am following this correctly, it sounds like you want to either ground the service through a properly-grounded-rebar ("foundation" ground) OR use the traditional copper rod driven down in the earth... but not both.

If you do both you can have potential between the two grounds.

I have to check with the inspector to see if we have to do both.

I don't see how the foundation ground can be better than using copper ground rods.

 

[jonyyuma]

My house was built before this requirement, but several years ago, i added cable and burgular alarm, then I added a 10 foot ground rod to the other end of the house and a #8 solid ground wire to the gas pipe and bonded to the other end.Ie single ground for the whole house, my home does not have metal plumbing...This supposed to help the alarm system function correctly. Jy..