This article was posted 11/11/2008 and is most likely outdated.

2008 NEC Questions and Answers November
 

 

Topic - NEC Questions
Subject - 2008 NEC Questions and Answers November

November 11, 2008
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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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Comments
  • Q. no. 6: 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. I did not find Table 210.23 in 2008 NEC. Thanks.

    K. Alam
    Reply to this comment

  • Q11. Until I read this I did not know that a feeder for pool equipment must be in a raceway. I have before just ran an "SER (4 conductor for single phase)" for the pool equipment. Can you explain the reason behind this, so that if I pre-wire for a pool, I can justify the additional cost to those involved? Thanks..

    JDB3
    Reply to this comment

  • Your answer to the question on code compliance of receptacle at a science lab sink vs the unidentified response example of a requirement within 6ft of a sink lacks clarity for the uninformed. It comes across as a yes but no answer. You can do better than that.

    peter bowers
    Reply to this comment

  • I do not agree to the answer to question 9. I use Arlington Industries plastic NM cable connectors. On the package it lists the differant combinations of cables that can be installed in one connector. It does list "multiple cabes" combinations. I am assuming since this is listed on the package that UL has approved this use.

    Brian Hobbs
    Reply to this comment

  • Good Educational information.

    Thanks

    Pradip deasi
    Reply to this comment

  • Q&A 6, just a little clarification. If the circuit contains a single receptacle, then the answer is yes, 210.21(B)(1). Also, the table reference should be Table 210.21(B)(3).

    Ed Patten
    Reply to this comment

  • Also is a sink is nearby.

    Lorenzo
    Reply to this comment

  • in section 645, as I read it, if the wiring is enclosed in a metal raceway it would not have to be removed.

    Hal Sullivan
    Reply to this comment

  • Q8-multiple NM cables in a single KO. Arlington makes a plastic NM cable clamp rated for 2 cables. I believe the number is NM50 for 1/2" KO & NM75 for 3/4" KO. In this case, putting 2 cables in the same KO is installing according to manufacturers instructions.

    Dan

    Dan
    Reply to this comment

  • I may be reading this wrong but Q13 and A13 don't seem to make any sense??

    MikeB
    Reply to this comment

  • Q5 height of receptacles in residential garage. A5 Any height? I thought minimum is 18"

    My journeyman in training has my 2008 book and another has my 2005 book so I can't look it up until tomorrow.

    Head Dragon Kid
    Reply to this comment

  • Grommets or hit lock connectors allow for 2 romex cables to enter a knockout.

    Eric Fries
    Reply to this comment

  • Question #1 Some break rooms don't have a sink. That also is part of the definition) Also if there were no counter and cooking appliance, wouldn't the receptacles within 6' of the sink be required to be GFCI protected? (210.8(B) (5)

    Lee
    Reply to this comment

  • In Question 10, a disconnect is required if the plug connection is not accessible. See 422.33(A)

    Amos Lowrance
    Reply to this comment

  • Mike, As always, I appreciate the thought provoking questions.

    Some observations: Q.1. I liked your revision in response to Lee.

    Q.7. See also 430.9

    Q.8. Looking at the question and answer, I am wondering if there might be some ambiguity. The question seems to center on the multiple cable issue, which has been addressed by others. The answer seems to address this through the perspective of any cables entering the box without going through a proper connector.

    Q11. When I first read this, I looked at it from the perspective of bringing a cable to the panel that was feeding a non-pool load. Code 680.25 on feeders leaves me scratching my head a bit. How far must the conduit extend from the panel? Is it not permissible to run a URD cable to the panel if it is in conduit through the floor to the box? Could I not run a type SE cable to this panel from an existing panel in my house if the pool equipment room was attached to the house? Would it have to be in conduit all the way from the main panel in the house to the subpanel for the pool? Or from the pool subpanel to where the cable leaves the pool equipment room?

    Thanks again for keeping us thinking, Wes

    Wes Gerrans
    Reply to this comment

  • Q6. Do I need to use 20A GFCI duplex receptacles for a 20A circuit? A6. No, Table 210.21(B)(3) allows a 15A receptacle on a 20A circuit.

    210.23 states for two or more receptacle that Table 210.21(B)(2) can be use, which then says that a 15 or 20 amp receptacle can be use. -- in no case can the load exceed the branch circuits rating. If you use a single receptacle I think the code will require you to use a 20A rated receptacle.

    Also on question #8 cables must be secured to the enclosure with fittings designed and listed for the cable [312.5(C)] -- the section does not say that only one wire is allowed - it does say that the cable must be secured to the cabinet. PS there are NMC connectors rated for more than one wire

    PS I enjoy your sharing of question -- I teach CEU classes and they help me stay on top of interesting question that may arise concerning the NEC codes

    john gary
    Reply to this comment

  • I thought you could bring 2 nm cables into the same ko of a panel as long as it was the split (atomic) type not the two screw cast type. In response to question 8

    Sherman
    Reply to this comment


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