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Grounding vs Bonding: 250.119 Identification of Equipment Grounding (Bonding) Conductor

July 7, 2006  

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250.119 Identification of Equipment Grounding (Bonding) Conductor.

Unless required to be insulated, equipment grounding (bonding) conductors can be bare.

Author’s Comment: Equipment grounding (bonding) conductors must be insulated for patient care equipment [517.13(B)] and permanently installed pool, outdoor spa, and outdoor hot tub equipment [680.21(A)(1), 680.23(F)(2), and 680.25(B)].
Individually covered or insulated equipment grounding (bonding) conductors must have a continuous outer finish that is either green or green with one or more yellow stripes.

Author’s Comment: Isolated ground circuits [250.96(B)] and isolated ground receptacles [250.146(D)] frequently use a green insulated conductor for equipment and a green insulated conductor with yellow stripes for the sensitive electronic equipment. Figures 250–165 and 250–166
Conductors with insulation that is green, or green with one or more yellow stripes cannot be used for an ungrounded or grounded neutral conductor. Figure 250–167

Author’s Comment: The NEC neither requires nor prohibits the use of the color green for the identification of bonding and grounding electrode conductors. Figure 250–168

(A) Conductors Larger Than 6 AWG

(1) Identified Where Accessible. Equipment grounding (bond¬ing) conductors larger than 6 AWG that are insulated can be permanently reidentified at the time of installation at every point where the conductor is accessible.

Exception: Identification of equipment grounding (bonding) conductors larger than 6 AWG in conduit bodies is not required.

(2) Identification Method. Equipment grounding (bonding) conductor identification must encircle the conductor and be accomplished by one of the following:
(a) Stripping exposed insulation
(b) Coloring exposed insulation green
(c) Marking exposed insulation with green tape or green adhesive labels

 

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Figure 250–165
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Figure 250–166
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Figure 250–167
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Figure 250–168
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Copyright © 2006 Mike Holt Enterprises,Inc.
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Comments
  • Oh yeah, an insulated equipment grounding wire or grounding electrode conductor will be more corrosion resistant all other things being equal than a bare conductor. Insulation also provides chemical as well as electrical insulation. If you can seal the connection to a lug with type 1 room temperature vulcanizing sealant or Scotchcast that is even better.

    However, stranded wire does suffer from the problem that corrosive gases, vapors, aerosols, and liquids can flow up between the strands and produce hidden corrosion inside of the insulation. Hence, the invention of Pirelli Strandseal conductor that has a strand blocking compound. Wire strands that are plated with Indium, Nickel, or Tin also are more corrosion resistant - which kind of plating to use depends on what kind of corrosives that are in the environment.

    Also, stranded conductors offer more surface are for corrosives to attack than solid wire.

    Stranded conductors can also suffer from some of the wire strands NOT conducting electricity particularly when the conductor ages even in a dry allegedly noncorrosive environment.

    It is also more likely that solid conductor will be subjected to the #220 silicon carbide abrasive paper elbow grease electrical grease method thus producing a better connection.

    I also have some experience with a place that recycles foundry wastes from aluminum foundries. The molding materials liberate ammonia gas when wet which is murder on copper wire even though the concentration is low enough that the air is breathable. The fluxing salts are a mixture of sodium chloride, potassium chloride, and sodium fluoride. The combination of ammmonia, fluxing chlorides, oxygen,m and water will dissolve every useful metal that there is except Indium and Bismuth. In the watewater treatment building of this place stainless steel just simply rots.

    I have also worked in a food plant where stainless steel machine screw threads would rust!

    For these

    Michael R. Cole

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