#1 awg common grounding electrode/#6 boding jumper

[tld38]

Hello to all, Common grounding electrode (AWG#1) through parts of building. ran into soffit that had 6 ft of 1 inch Flexible metal conduit with bonding bushings on both sides. I was told that you could run a #6 through the flex with the #1 AWG, and tie the #6 to both boding bushings. I do not believe this is correct. Can you please tell me code section that clarifies this, if I am right.
Question #2. The common grounding electrode conductor is being tapped at several locations to bod transformers throughout the building. I was told that it is ok to run the common #1 grounding electrode directly to a bus bar, and come off the bus bar to the next bus bar. My understanding is that a common GEC must be cadwelded or compression spliced without relying on the busbar for continuity of the common GEC. Can you please site a code section that clarifies this? Also I read somewhere, that a common GEC must be minimum #3/0 AWG. Any and all help for the several questions are greatly appreciated. I always have come to this site with questions, as there is great experience here. Thanks much

 

[Dennis Alwon]

Article 250.30(A)(6) is what I think you are looking for.

(6) Grounding Electrode Conductor, Multiple Separately Derived Systems.
A common grounding electrode conductor for multiple separately derived systems shall be permitted. If installed, the common grounding electrode conductor shall be used to connect the grounded conductor of the separately derived systems to the grounding electrode as specified in 250.30(A)(4). A grounding electrode conductor tap shall then be installed from each separately derived system to the common grounding electrode conductor. Each tap conductor shall connect the grounded conductor of the separately derived system to the common grounding electrode conductor. This connection shall be made at the same point on the separately derived system where the system bonding jumper is connected.

Exception No. 1: If the system bonding jumper specified in
250.30(A)(1) is a wire or busbar, it shall be permitted to
connect the grounding electrode conductor tap to the equipment
grounding terminal, bar, or bus, provided the equipment
grounding terminal, bar, or bus is of suffıcient size for the
separately derived system.

Exception No. 2: A grounding electrode conductor shall not
be required for a system that supplies a Class 1, Class 2, or
Class 3 circuit and is derived from a transformer rated not
more than 1000 volt-amperes, provided the system grounded
conductor is bonded to the transformer frame or enclosure by
a jumper sized in accordance with 250.30(A)(1),

Exception No. 3, and the transformer frame or enclosure is grounded by
one of the means specified in 250.134.

(a) Common Grounding Electrode Conductor. The common
grounding electrode conductor shall be permitted to be
one of the following:

(1) A conductor of the wire type not smaller than 3/0 AWG
copper or 250 kcmil aluminum

(2) The metal frame of the building or structure that complies
with 250.52(A)(2) or is connected to the grounding
electrode system by a conductor that shall not be
smaller than 3/0 AWG copper or 250 kcmil aluminum

(b) Tap Conductor Size. Each tap conductor shall be
sized in accordance with 250.66 based on the derived ungrounded
conductors of the separately derived system it serves.

Exception: If the source of a separately derived system is
located within equipment listed and identified as suitable
for use as service equipment, the grounding electrode conductor
from the service or feeder equipment to the grounding
electrode shall be permitted as the grounding electrode
conductor for the separately derived system, provided that
the grounding electrode conductor is of suffıcient size for
the separately derived system. If the equipment grounding
bus internal to the equipment is not smaller than the required
grounding electrode conductor for the separately derived system,
the grounding electrode connection for the separately
derived system shall be permitted to be made to the bus.

(c) Connections. All tap connections to the common
grounding electrode conductor shall be made at an accessible
location by one of the following methods:

(1) A connector listed as grounding and bonding equipment.

(2) Listed connections to aluminum or copper busbars not
smaller than 6 mm × 50 mm (1⁄4 in. × 2 in.). If aluminum
busbars are used, the installation shall comply
with 250.64(A).

(3) The exothermic welding process.
Tap conductors shall be connected to the common
grounding electrode conductor in such a manner that the
common grounding electrode conductor remains without a
splice or joint.

 

[jumper]

Hello to all, Common grounding electrode (AWG#1) through parts of building. ran into soffit that had 6 ft of 1 inch Flexible metal conduit with bonding bushings on both sides. I was told that you could run a #6 through the flex with the #1 AWG, and tie the #6 to both boding bushings. I do not believe this is correct. Can you please tell me code section that clarifies this, if I am right.

250.64(E)(3) Size.
The bonding jumper for a grounding electrode
conductor raceway or cable armor shall be the same size as,
or larger than, the enclosed grounding electrode conductor.