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Service Maintenance Company, Inc. Electrical Contractors |
| NEC Questions and Answers | 8/8/2003 |
| By Mike Holt for ECM Magazine Q1. Does the Code require a local disconnect on the primary side of a transformer? A1. No, just overcurrent protection in accordance with 450.3(B). Q2. Can you tell me where the Code rule is about operating handles for switches and circuit breakers used as switches not being more than 6 ft 7 in. above the floor or working platform? A2. This rule is contained in 404.8(A), which also requires switching devices to be located so that they may be operated from a readily accessible place. However, exception 2 allows switching devices to be above this height, if installed adjacent to motors, appliances, or other equipment. Q3. Is there a NEC requirement that an equipment grounding conductor be installed in PVC conduits? A3. Kinda. 352.60 states that where equipment grounding (bonding) is required by Article 250, a separate equipment grounding (bonding) conductor shall be installed in the conduit. So the key is if equipment grounding (bonding) is required by Article 250, and the installation is nonmetallic conduit, then an equipment grounding (bonding) conductor must be installed. But the exceptions to 352.60 permit the grounded (neutral) conductor to be used for bonding at the following locations [250.142(A)]: (1) On the supply side or within the enclosure of the service disconnecting means [250.24(B)]. (2) On the supply side or within the enclosure of the disconnecting means for separate buildings [250.32(B)]. (3) On the supply side or within the enclosure of the disconnecting means of separately derived systems [250.30(A)(1)]. Q4. What is the NEC color code requirement for 120/208V and 277/480V systems? A4. The NEC does not contain color code requirement for ungrounded conductors, except 110.15 requires the high-leg conductor from a 120/240 4-wire delta-connected system to be identified with the color orange. The grounded (neutral) conductors must be identified with the color white or gray in accordance with 200.6 and equipment grounding (bonding) conductors must be bare, or identified in the color green, or green with a yellow strip if insulated in accordance with 250.119. Q5. We are encountering situations in high-rise condos where they are installing very small laundry closets, sometimes in bathrooms! The combo washer/dryer receives power from a single 30A, 240V outlet. Am I still required to install the 20A receptacle circuit for the laundry room? A5. Yep, the 20A receptacle circuit is still required [210.11(C)(2)] because someone might replace the 30A combo washer/dryer with a unit that requires a 20A receptacle. Q6. Is it a code violation to install a 3-phase main breaker panel for a single-phase service and a 3-phase breaker for a single-phase panel? I would say it is not listed for this purpose; therefore this would be a violation. A6. There is nothing in the NEC that would prohibit this installation unless the these parts were installed in violation of manufacturers instructions [110.3(B)]. Q7. I am handling an automobile claim where one of our insured's struck an electrical wire that was attached to a building. The height of our insured's tractor-trailer is 13'6. I am trying to determine if the NEC lists the height requirement for electrical wiring above parking lot/streets. I feel I can deny this loss based upon the fact the height of the wire was below the standard. I just need to verify where I can find that information. A7. The minimum height of overhead conductor spans over public streets, alleys, roads, and parking areas subject to truck traffic shall not be less than 18 ft [225.18]. Q8. I strongly feel that a 120V outdoor receptacles for sump pump equipment in an industrial plant be plugged into a GFCI receptacle for personnel safety. Is there a NEC article that addresses it directly or indirectly? What Code rule requires a receptacle for drinking fountains in commercial/industrial setting to be GFCI protected? A8. Sorry, but the NEC does not require GFCI protection for any of these applications. Q9. I remember reading somewhere that an inspector couldn't make a contractor chip out the footer to create a concrete encased electrode. Is there such a ruling and if so could you quote it. It seems to me that chipping out the footer creates a building code violation. A9. No the NEC does not require that a concrete encased electrode be made accessible. If the concrete is already poured, then it's simply not available. I base my comments on the NFPA Formal Interpretation 78-4, which is contained in the NEC Handbook. Reference: Article 250.50 Question: Is it the intent of 250.50 that reinforcing steel, if used in a building footing, must be made available for grounding? Answer: No. Issue Edition: 1978 Reference: 250-81 Issue Date: March 1980 Q10. Can a duplex receptacle be used as a splice point for other outlets in the circuit? I was under the impression that each box was to have a pigtail for the receptacle and not use the receptacle as a splice means. A10. This is a product standard issue, not a NEC requirement. Wiring devices are listed for this purpose. However, the continuity of a grounded (neutral) conductor for multiwire branch circuits shall not depend on device connections [300.13(B)]. |
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