This article was posted 12/03/2009 and is most likely outdated.

2008 NEC Questions and Answers - December 2009
 

 

Topic - NEC
Subject - 2008 NEC Questions and Answers - December 2009

December 3, 2009
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NEC Questions and Answers based on 2008 NEC
December 2009

By Mike Holt for EC&M Magazine

Here’s the follow up to yesterday’s newsletter. This includes all of the answers to the questions sent, so you can see how you did.

Q1. Do I need to ground/bond to the metal fire sprinkler piping systems?
A1. The metal water piping system must be bonded as required in 250.104(A)(1), (A)(2), or (A)(3). The bonding jumper must be copper where within 18 in. of earth [250.64(A)], securely fastened to the surface on which it’s mounted [250.64(B)], and adequately protected if exposed to physical damage [250.64(B)]. In addition, all points of attachment must be accessible [250.104(A)].

In response to a Code change proposal in 2008, the technical committee state that “A metallic fire sprinkler piping system is metal water piping system that is covered by Section 250.104(A). Section 250.104(A) does not differentiate or exclude between the various types of metal water piping systems that might be present in a building or structure.” Refer to proposal 5-240 Log #1448 for more information.

Q2. I recently failed an inspection for having a 15A GFCI receptacle on a 20A branch circuit in the master bath. Is the inspector correct?
A2.Assuming that the receptacle was not of the singular type, your inspector is not correct. Where connected to a branch circuit that supplies two or more receptacles, receptacles must have an ampere rating in accordance with the values listed in Table 210.21(B)(3), which allows for a duplex 15A receptacle on a 20A branch circuit.

Q3. Is there a Code rule that tells you that you cannot store items in the electrical room?
A3. The electrical room can contain storage items, but the working space required by 110.26 must be clear at all times.

Q4. I am doing a remodel on a very old home with 2-wire NM cable and nongrounding type receptacles. We want to add receptacles, but aren’t sure how to ground them. What are my options?
A4. Where a nongrounding receptacle is replaced with a grounding-type receptacle from an outlet box that doesn’t contain an equipment grounding conductor, the grounding contacts of the receptacle must be connected to one of the following [250.130(C)]: Figure 250–191
(1) Grounding electrode system [250.50]
(2) Grounding electrode conductor
(3) Panelboard equipment grounding terminal
(4) Service neutral conductor
It is worth noting that a grounding-type receptacle can replace a nongrounding type receptacle, without having the grounding terminal connected to an equipment grounding conductor if the receptacle is GFCI protected and marked in accordance with 406.3(D)(3).

Q5. I have been using SER cable for nearly twenty years. I am now being told that I can’t use it because it’s not in the Code. I have searched for “SER”, and I can’t find it either! What is the deal?   
A5. Great question, because you won’t find the term “SER” in the Code. SER cable is actually SE cable with an insulated neutral, resulting in three insulated conductors with an uninsulated equipment grounding conductor. SER cable is round (hence the acronym), while 2-wire SE cable is flat. SER is covered by Article 338.

Q6. Can 14-2 NM Cable be used for the travelers of a three way switch?
A6. Yes, according to 404.2(A); wiring for 3-way and 4-way switching must be done so that only the ungrounded conductors are switched. Figure 404–2

Author’s Comment: In other words, the neutral conductor must not be switched. The white insulated conductor within a cable assembly can be used for single-pole, 3-way, or 4-way switch loops if it’s permanently reidentified to indicate its use as an ungrounded conductor at each location where the conductor is visible and accessible [200.7(C)(2)].

Where a metal raceway or metal-clad cable contains the ungrounded conductors for switches, the wiring must be arranged to avoid heating the surrounding metal by induction. This is accomplished by installing all circuit conductors in the same raceway in accordance with 300.3(B) and 300.20(A), or ensuring that they’re all within the same cable.

Ex: A neutral conductor isn’t required in the same raceway or cable with travelers and switch leg (switch loops) conductors. Figure 404–3

Q7. In an EMT installation, does the equipment grounding conductor need to be connected to each junction box if the boxes contain no splices (the conductors are pulled straight through)?
A7. No. Only when  circuit conductors are spliced or terminated on equipment within a metal box, does the equipment grounding conductor associated with those circuits need to be connected to the box [250.148].

Q8. We are being told that a 16 AWG conductor is too small to use for a control conductor. Is this true?
A8. No. Conductors of sizes 18 AWG and 16 AWG installed in a raceway, enclosure, or listed cable are permitted if they don’t supply a load that exceeds the ampacities given in 402.5. Conductors of 14 AWG and larger must not supply loads greater than the ampacities given in 310.15 [725.49(A)].
In addition, overcurrent protection for conductors 14 AWG and larger must be in accordance with the conductor ampacity, without applying the ampacity adjustment or correction factors of 310.15, and overcurrent protection must not exceed 7 amperes for 18 AWG conductors and 10 amperes for 16 AWG.

Q9. Some of our transformers have factory installed bonding straps from the X0 terminal to the transformer enclosure. Looking at them, they seem very small. How do we know that these straps are big enough?
A9. Product evaluation for safety is typically performed by a testing laboratory, which publishes a list of equipment that meets a nationally recognized test standard. Products and materials listed, labeled, or identified by a testing laboratory are generally approved by the authority having jurisdiction. According to 90.7, “It is the intent of this Code that factory-installed internal wiring or the construction of equipment need not be inspected at the time of installation of the equipment, except to detect alterations or damage, if the equipment has been listed by a qualified electrical testing laboratory that is recognized as having the facilities described in the preceding paragraph and that requires suitability for installation in accordance with this Code.”

Q10. Can a receptacle that is installed on the exterior side of an attached garage be used as the required outdoor receptacle for a dwelling unit, or must that receptacle be mounted on the house itself?
A10. Two GFCI-protected 15A or 20A, 125V receptacle outlets that are accessible while standing at grade level must be installed outdoors for each dwelling unit, one at the front and one at the back, no more than 6½ ft above grade. The Code doesn’t specify that the receptacle be installed on the dwelling.

Q11. In a recent stay at a motel room I noticed something interesting. The bathroom was equipped with a hair dryer (attached to the wall) that was plugged into the only receptacle in the bathroom. On the bathroom countertop there was also a coffee maker plugged into the same receptacle. The hairdryer was 1,500W (12.5A), and the hairdryer was 6.5A. Is this situation legal?  
A11. Cord-and-plug-connected equipment not fastened in place, such as a hairdryer of coffee maker, must not have an ampere rating more than 80 percent of the branch-circuit rating [210.23(A)(1)].

UL and other testing laboratories list portable equipment (such as hair dryers) up to 100 percent of the circuit rating. The NEC is an installation standard, not a product standard, so it can’t prohibit this practice. There really is no way to limit the load to 80 percent of the branch-circuit rating if testing laboratories permit equipment to be listed for 100 percent of the circuit rating

Q12. Are AFCIs required for light fixtures and smoke alarms?
A12. All 15A or 20A, 120V branch circuits in dwelling units supplying outlets in family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, or similar rooms or areas must be protected by a listed AFCI device of the combination type [210.12(B)].

Smoke alarms connected to a 15A or 20A circuit of a dwelling unit must be AFCI protected if the smoke alarm is located in one of the areas specified In 210.12(B). The exemption from AFCI protection for the “fire alarm circuit” contained in 760.41(B) and 760.121(B) doesn’t apply to the single-or multiple-station smoke alarm circuit typically installed in dwelling unit bedroom areas. This is because a smoke alarm circuit isn’t a fire alarm circuit as defined in NFPA 72, National Fire Alarm Code. Unlike single-or multiple-station smoke alarms, fire alarm systems are managed by a fire alarm control panel.

 

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Comments
  • Would like to see a scatch on Q. 6!

    Jerry Roberts
    Reply to this comment

  • I never understood why you can put a 15amp outlet on a 20amp circuit. If I plug in something that pulls around 20 amps, that outlet is overloaded.

    jim
    Reply to this comment

  • Regarding the question about storage in electric rooms, NFPA® 1, Fire Code, 2009 Edition, states the following: 10.19.5.1 "Combustible material shall not be stored in boiler rooms, mechanical rooms, or electrical equipment rooms." and 10.19.5.2 "Materials and supplies for the operation and maintenance of the equipment in the room shall be permitted." We strongly discourage storage in true electric rooms at our facility, especially if voltage higher than 240 is present.

    CLF
    Reply to this comment

  • Regarding question #8 section 402-5 speaks to fixtures wires and not control wiring.

    wire size 16 & 18 table 402-5 states that the no conductor shall be used under such conditions that its operating temperature exceeds the temperature specified in table 402-5. so are you saying that as long as the control circuit using 16 or 18 gage wires do not exceed the amperage rate specified in 402.5 Are you saying that they can be used as control wire as long as they are protected by a What? a fuse rated at no more than 6 amp for 18 and 8 amps for 16 ?

    john gary
    Reply to this comment

  • Mike regarding the above question of a load larger than 20 amps on a 15 amp rated recpt. there is also question #11 and your answer. We often see where the 15 amp recpt. and connected wiring are burnt from counter top expresso machines and microwaves to the 1875 watt blow drier that is found in the home. The 2005 code change that required a 20 amp circuit in the kit. & bathroom has incouraged the market and home owners to buy these products but the results can be deadly in home that are built prior to the code change and adoption. Since Art, 210.23 (A1) out lines what a installer is to do how do we stop the customer from buying and using the above equipment?

    John K. Erickson
    Reply to this comment

  • Situation. Industrial Site. Restroooms with 4 sinks, next to each other on common wall. GFCI Receptacles for sure here, but how many and what would be the spacing along the wall of more than one receptacle is required? I'd like to get this one right as many like to argue where I work, if you get the picture! Thanks and hope to get a response quickly.

    Harold
    Reply to this comment

  • To question #3 about storage in electrical rooms. The NC Fire Code states that no combustible material shall be stores in boiler, mechanical, or electrical equipment rooms.

    Wayne
    Reply to this comment


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