Re: buford grounds?????
WV Sparktition said:
If so, where is it in the code?
250.50 requires you to use all the electrodes present. The exception is more aggressive in stating that as far as the NEC is concerned, only an old existing building gets out of using the concrete encased electrode.
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.
One important aspect of this is that 250.50 doesn't require you to install a CEE if one is
not present; it only requires you to make use of it if it's already present.
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 ( ? 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.
There is a lot of information there.
- If rebar is present, and
- It's encased in 2" of concrete for a distance of at least 20 feet, and
- It's at least 1/2" in diameter, and
- The concrete is in direct contact with soil, and
- The effective rebar is at the bottom of a foundation or footer,
Then you have a CEE you must use. If something isn't right (as in waterproofed concrete, less than 1/2" rebar, etc) then you don't have a CEE to connect to.
You can then elect to build one, if you want. If you want to construct one, the alternate method is there, so that you have something that the NEC considers an electrode.
Interestingly, I have yet to see a qualifying electrode at the job where I spend most of my time, but strangely a rebar sticks out for me to attach to from time to time.
IMO, the buzz this section has generated is pretty amuzing. It's the fad of the 2005 cycle, and suddenly folks are going off half-cocked and using the existing language of the NEC to require a CEE to be installed, whether it's genuinely present or not.
I call it Uferia.
