NEC Questions Based on the 2008 NEC
November
Here is the follow up to yesterday’s newsletter. This includes all of the answers to the questions sent yesterday so you can see how you did.
By Mike Holt for EC&M Magazine
Q1. Is GFCI protection required for receptacles above the counter of a break rooms in an office building?
A1. If the break room has permanent provisions for food preparation and cooking [Article 100 Kitchen], then all 125V, 15A and 20A receptacles in the kitchen area must be GFCI protected [210.8(B)].
Q2. If we are using self grounding receptacles with MC Cable and metal boxes, do we need to connect the equipment grounding conductor to the receptacle?
A2. No. Receptacle yokes listed as self-grounding are designed to establish the bonding path between the device yoke and a metal box via the two metal mounting screws [250.146(B)].
Q3. Where does NEC require removal of abandoned line voltage wiring?
A3. The only time the NEC requires removal of abandoned line voltage circuit conductors is in 372.13 for cellular concrete floors, 374.7 for cellular metal floors, 390.7 for underfloor raceways and 645.5(F) for information technology equipment.
Q4. Can a 45 KVA transformer be installed in the ceiling space above the ceiling grid?
A4. Dry-type transformers, rated not more than 50 kVA, are permitted above suspended ceilings or in hollow spaces of buildings, if not permanently closed in by the structure [450.13(B)].
Q5. How far above a residential garage floor do our receptacles need to be?
A5. The Code does not require any specific height for equipment located in residential garages. Receptacles may be mounted as low or as high as you would like them to be.
Q6. Do I need to use 20A GFCI duplex receptacles for a 20A circuit?
A6. No, Table 210.23 allows a 15A receptacle on a 20A circuit.
Q7. Does the NEC contain torque requirements for conductor terminations?
A7. No, but it does have a Fine Print Note in 110.14 that states “Conductors must terminate in devices that have been properly tightened in accordance with the manufacturer’s torque specifications included with equipment instructions. Failure to torque terminals can result in excessive heating of terminals or splicing devices (due to a loose connection), which can result in a fire because of a short circuit or ground fault. In addition, this is a violation of 110.3(B), which requires all equipment to be installed in accordance with listing or labeling instructions.”
Q8. Can we put multiple NM Cables through a single knockout in a panel?
A8. No, cables must be secured to the enclosure with fittings designed and listed for the cable [312.5(C)].
Q9. How many isolated ground receptacles can share the same isolated grounding conductor?
A9. As many as you want.
Q10. If an appliance is cord and plug connected, is a disconnecting means required?
A10. No, a plug and receptacle can serve as the disconnecting means for a cord-and-plug-connected appliance [422.33(A)].
Q11. We had a new swimming pool installed at our house, and the electricians ran a cable to the pool equipment room panel. Is this legal?
A11. No. Feeder conductors to a panelboard for a permanently installed pool must be installed in rigid metal conduit, intermediate metal conduit, liquidtight flexible nonmetallic conduit, or PVC conduit. Electrical metallic tubing is permitted where installed on or within a building, and electrical nonmetallic tubing is permitted where installed within a building [680.25].
Q12. Some areas of the Code state that schedule 80 PVC conduit is suitable for protection against physical damage. With that said, are the burial depths for schedule 40 and schedule 80 different?
A12. No, they are the same [300.5]
Q13. In our local high school science lab there are receptacles installed four inches from the edge of a sink. Is this okay by the NEC?
A13. Yes, but all 15A and 20A, 125V receptacles installed within 6 ft of the outside edge of a sink must be GFCI protected [210.8(B)(5)].
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