WAC 296-46B-250
Wiring and protection -- Grounding and
bonding.
028 (D)(3) Separately derived system with more than one
enclosure.
(1) NEC 250.28 (D)(3) is amended to read: Where a
separately derived system supplies more than a single
enclosure, the system bonding jumper for each enclosure shall
be sized in accordance with 250.28 (D)(1) based on the largest
ungrounded feeder/tap conductor serving that enclosure, or a
single system bonding jumper shall be installed at the source
and sized in accordance with 250.28 (D)(1) based on the
equivalent size of the largest supply conductor determined by
the largest sum of the areas of the corresponding conductors
of each set.
052 Grounding electrodes.
(2) If a concrete encased electrode is installed,
inspection may be accomplished by the following methods:
(a) At the time of inspection of other work on the
project, providing the concrete encased electrode is
accessible for a visual inspection;
(b) At the time of the service inspection providing the
installer has provided a method so the inspector can verify
the continuity of the electrode conductor along its entire
length (e.g., attaching a length of copper wire to one end of
the electrode that reaches the location of the grounding
electrode conductor that will enable the inspector to measure
the resistance with a standard resistance tester). The
concrete encased electrode does not have to be accessible for
a visual inspection; or
(c) Other method when prior approval, on a job site
basis, is given by the inspector.
If a special inspection trip is required to inspect a
grounding electrode conductor, a trip fee will be charged for
that inspection in addition to the normal permit fee.
056 Resistance of rod, pipe, and plate electrodes.
(3) For rod, pipe and plate electrodes, if a ground
resistance test is not performed to ensure a resistance to
ground of twenty-five ohms or less, two or more electrodes as
specified in NEC 250.52 must be installed a minimum of six
feet apart. A temporary construction service is not required
to have more than one made electrode.
(4) For services only, when multiple buildings or
structures are located adjacent, but structurally separate
from each other, any installed rod, pipe, or plate electrodes
used for those services must be installed so that each
building's or structure's electrodes are not less than 1.8 m
(6 ft) apart from the adjacent building's or structure's
electrodes.
068 Accessibility.
(5) The termination point of a grounding electrode
conductor tap to the grounding electrode conductor must be
accessible unless the connection is made using an exothermic
or irreversible compression connection.
090 Bonding.
(6) Metallic stubs or valves used in nonmetallic plumbing
systems are not required to be bonded to the electrical system
unless required by an electrical equipment manufacturer's
instructions.
(7) Hot and cold water plumbing lines are not required to
be bonded together if, at the time of inspection, the
inspector can determine the lines are mechanically and
electrically joined by one or more metallic mixing valves.
094 Bonding for other systems.
(8) NEC 250.94 is not adopted.
(9) An accessible means external to enclosures for
connecting intersystem bonding and grounding electrode
conductors must be provided at the service equipment and at
the disconnecting means for any additional buildings or
structures by at least one of the following means:
(a) Exposed nonflexible metallic raceways;
(b) Exposed grounding electrode conductor or electrode;
(c) Approved means for the external connection of a
copper or other corrosion-resistant bonding or grounding
conductor to the grounded raceway or equipment.
104(B) Bonding - other metal piping.
(10) For flexible metal gas piping, installed new or
extended from an existing rigid metal piping system, either:
(a) Provide a copy of the manufacturer's bonding
instructions to the inspector at the time of inspection and
follow those instructions; or
(b) The bonding conductor for the gas system must:
(i) Be a minimum 6 AWG copper; and
(ii) Terminate at:
(A) An accessible location at the gas meter end of the
gas piping system on either a solid iron gas pipe or a cast
flexible gas piping fitting using a listed grounding
connector; and
(B) Either the service equipment enclosure, service
grounding electrode conductor or electrode, or neutral
conductor bus in the service enclosure.
184 Solidly grounded neutral systems over 1 kV.
(11) In addition to the requirements of NEC 250.184(A),
the following applies for:
(a) Existing installations.
(i) The use of a concentric shield will be allowed for
use as a neutral conductor for extension, replacement, or
repair, if all of the following are complied with:
(A) The existing system uses the concentric shield as a
neutral conductor;
(B) Each individual conductor contains a separate
concentric shield sized to no less than thirty-three and
one-half percent of the ampacity of the phase conductor for
three-phase systems or one hundred percent of the ampacity of
the phase conductor for single-phase systems;
(C) The new or replacement cable's concentric shield is
enclosed inside an outer insulating jacket; and
(D) Existing cable (i.e., existing cable installed
directly in the circuit between the work and the circuit's
overcurrent device) successfully passes the following tests:
• A cable maintenance high potential dielectric test.
The test must be performed in accordance with the cable
manufacturer's instruction or the 2001 NETA maintenance test
specifications; and
• A resistance test of the cable shield. Resistance must
be based on the type, size, and length of the conductor used
as the cable shield using the conductor properties described
in NEC Table 8 Conductor Properties.
An electrical engineer must provide a specific
certification to the electrical plan review supervisor in
writing that the test results of the maintenance high
potential dielectric test and the resistance test have been
reviewed by the electrical engineer and that the cable shield
is appropriate for the installation. The electrical engineer
must stamp the certification document with the engineer's
stamp and signature. The document may be in the form of a
letter or electrical plans.
Testing results are valid for a period of seven years
from the date of testing. Cable will not be required to be
tested at a shorter interval.
(ii) A concentric shield used as a neutral conductor in a
multigrounded system fulfills the requirements of an equipment
grounding conductor.
(b) New installations.
(i) New installations do not include extensions of
existing circuits.
(ii) The use of the concentric shield will not be allowed
for use as a neutral conductor for new installations. A
listed separate neutral conductor meeting the requirements of
NEC 250.184(A) must be installed.
[Statutory Authority: RCW 19.28.006, 19.28.010, 19.28.031,
19.28.041, 19.28.061, 19.28.101, 19.28.131, 19.28.161,
19.28.171, 19.28.191, 19.28.201, 19.28.211, 19.28.241,
19.28.251, 19.28.281, 19.28.311, 19.28.321, 19.28.400,
19.28.420, 19.28.490, 19.28.551. 08-24-048, § 296-46B-250,
filed 11/25/08, effective 12/31/08; 06-24-041, § 296-46B-250,
filed 11/30/06, effective 12/31/06; 06-05-028, § 296-46B-250,
filed 2/7/06, effective 5/1/06; 05-10-024, § 296-46B-250,
filed 4/26/05, effective 6/30/05. Statutory Authority: RCW 19.28.006, 19.28.010, 19.28.031, 19.28.041, 19.28.061,
19.28.101, 19.28.131, 19.28.161, 19.28.171, 19.28.191,
19.28.201, 19.28.211, 19.28.241, 19.28.251, 19.28.271,
19.28.311, 19.28.321, 19.28.400, 19.28.420, 19.28.490,
19.28.551, 2003 c 399, 2003 c 211, 2003 c 78, and 2003 c 242. 04-12-049, § 296-46B-250, filed 5/28/04, effective 6/30/04. Statutory Authority: RCW 19.28.006, 19.28.010, 19.28.031,
19.28.041, 19.28.061, 19.28.101, 19.28.131, 19.28.161,
19.28.171, 19.28.191, 19.28.201, 19.28.211, 19.28.241,
19.28.251, 19.28.271, 19.28.311, 19.28.321, 19.28.400,
19.28.420, 19.28.490, 19.28.551, 2002 c 249, chapters 34.05 and 19.28 RCW. 03-09-111, § 296-46B-250, filed 4/22/03,
effective 5/23/03.]