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Can I mark the ends of conductors with paint?

Jun 1, 1998 12:00 PM, Edited by Robert J. Lawrie

Q. Is it permitted to spray white paint on the end of a black, red, or blue conductor to indicate it is a grounded conductor? —M.H.M.

A. Sec. 200-6 of the NEC is very explicit in requiring that conductors No. 6 or smaller be identified by a continuous outer finish for their entire length. Sizes larger than No. 6 are permitted to be identified by this painting method. However, those conductors are available from various manufacturers in one color—black. It is the intent of the Code to require that the proper color be used when such coloring is available from the manufacturer. That’s our company’s standard.

We have had several instances where the color codes required by the Code and company’s specifications have not been followed, and the electrical contractor offered to paint the wires rather than admit he purchased and installed the wrong colors initially. Identifying wires by means of paint, tape, tag, etc. is acceptable only for wire that is not available in that particular color. It is our understanding this is the intent behind the Code. — L.W.M.

A. M.H.M. may mark each of non-white color insulated grounded conductors at the time of installation using distinctive white marking at terminations. These conductors must be larger than No. 6, per NEC Sec. 2 10-6b.

Painting the insulated ends of conductors has the following deficiencies: wet paint may be electrically conductive; dry paint may not adhere permanently to the conductor’s insulation; and paint has a habit of severely fading and discoloring over time so that its original color (and specific NEC identity) becomes lost. M.H.M. should wrap each grounded conductor’s end insulation with white colored electrical grade tape. This is a proven long-term identification method. —F.M.P.

A. Sec. 200-6a of the NEC says an insulated grounded conductor of No.6 or smaller shall be identified by a continuous white or natural gray outer finish along its entire length. However, there are five exceptions in the section that allow such marking on the ends of conductors sized No. 6 or smaller including the following: 1) multiconductor varnished-cloth-insulated cables; 2) fixture wires as outlined in Art. 402; 3) grounded conductors in multiconductor cables can be so marked where conditions of maintenance and supervision ensure only qualified persons will service the installation; 4) mineral-insulated, metal-sheathed cable; and 5) Exception No. 5 states “A single-conductor sunlight-resistant, outdoor-rated cable used as a grounded conductor in photovoltaic power systems, as permitted by Sec. 690-31, shall be identified at the time of installation by a distinctive marking at its termination.”

This is a single-conductor cable, which can easily be considered a “conductor.” —E.Y.

A. We must consider two NEC sections. All references are to the 1996 NEC. Under Art. 200 (Use and Identification of Grounded Conductors) Sec. 200-6a, Exception No. 3 and Sec.200-6b, Exception indicate it is permissible to reidentify the ends of insulated grounded conductors. Such identification can be a distinctive white marking. In cases where the exceptions do not apply, the entire length of the conductor can be identified in the same manner. Sec. 210-5a of Art. 210 (Branch Circuits) contains similar provisions.

Also, such above re-identification must comply with Sec. 110-11. This section addresses deteriorating agents and states “…no conductors shall be exposed to liquids or other agents having a deteriorating effect on the conductors…”

To be in compliance with this requirement, it must be indicated that the application of paint, or any other means of marking, will not be detrimental to the rubber, thermoplastic, thermoset, etc. —M.L.L.

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