This article was posted 09/28/2006 and is most likely outdated.

NEC Questions and Answers - September 2006 (Part 2)
 

 
Topic - NEC Questions
Subject - NEC Questions and Answers - September 2006 (Part 2)

September 28, 2006  

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NEC Questions and Answers

 

By Mike Holt for EC&M Magazine

 

Q1.Can a panel be installed in a residential bathroom? What about a bedroom?

A1. The NEC does not permit overcurrent protection devices to be located in the bathrooms of dwelling units, or guest rooms or guest suites of hotels or motels [240.24(E)]. Nothing in the code prohibits panels from being installed in bedroom.

 

Q2. Must I use a flexible wiring method for a 112.5 kVA dry-type transformer?

A2. No. Rigid metal conduit is often use in industrial installations for this purpose.

 

Q3. What are the rules on mixing emergency circuits in the same raceway or enclosure with nonemergency circuits?

A3. To ensure that a fault on the normal wiring circuits will not affect the performance of emergency wiring or equipment, all wiring from an emergency source, or emergency source distribution overcurrent protection, to emergency loads must be kept entirely independent of all other wiring and equipment, except as permitted for [700.9(B)]:

(1)       Wiring in transfer equipment enclosures

(2)       Wiring supplied from two sources in exit or emergency luminaires

(3)       Wiring from two sources in a common junction box, attached to exit or emergency luminaires

 

Q4. I recently saw an advertisement that red EMT conduit was required for emergency circuits. Is this a code requirement?

A4. No, only boxes and enclosures, including transfer switches, generators, and power panels for emergency circuits must be permanently marked as components of an emergency system [700.9(A)].

 

Q5. Can power conductors for an intercom system be mixed in the same raceway with the audio output conductors?

A5. No. Audio output circuits using Class 2 or Class 3 wiring methods must not be placed in any enclosure, raceway, or cable with conductors of electric light, power circuits [640.9(C) and 725.55].

 

Q6. What are the limitations on the use of rigid nonmetallic conduit underground for a gasoline dispenser?

A6. Rigid nonmetallic conduit can be installed underground below a Class I location if the raceway is covered with not less than 2 ft of earth, concrete, or asphalt [514.8 Exception 2]. However, threaded rigid metal or threaded intermediate metal conduit must be used for the last 2 ft of the underground run.

 

Q7. I have a house with a detached garage for aircraft. Are there any special rules that I need to know about?

A7. Yes Article 513 has lots of very stringent requirements for buildings or structures in which aircraft might undergo service, repairs, or alterations.

 

Q8. What are the NEC requirements for using electrical metallic tubing (EMT) to physically protect NM cable?

A8. For one, a nonmetallic bushing or adapter must be installed at the point where the cable enters the raceway [300.15(C)] and in unfinished basements the raceway and metal outlet boxes must be grounded (bonded) to an effective ground-fault current path in accordance with 250.148 [334.15(C)].

 

Q9. Does the NEC require safety chains on a high bay lighting fixtures?

A9. No, although your locally adopted building code might have rules for seismic restraint. Check with your local building inspector for information.

 

Q10. Can NM cable be used to wire a hot tub? What about a hydromassage bathtub?

A10. Outdoor hot tub motors must be installed in rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or Type MC cable listed for the location (sunlight-resistant or for direct burial) [680.21(A)]. Indoor installations of hot tubs can be connected by any of the wiring methods contained in Chapter 3 [680.43]. Hydromassage tubs are also allowed to be installed by using any of the Chapter 3 wiring methods.

 

 

 

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Comments
  • Oh! Hi! This - TEST MESSAGE! WELLCOM IN DRAMADOM! TEST MESSAGE! WELLCOM IN DRAMADOM! TEST MESSAGE! WELLCOM IN DRAMADOM! Oh! Hi! This - TEST MESSAGE! WELLCOM IN DRAMADOM!

    Ron
    Reply to this comment

  • I have 2 sets of 500 thousands running through a box parallel to eachother and you polytap all 8 of them to feed meterbanks which are attached by 2 chase nipples to the box. Is it okay that the sets of wire are split up going into the meter bank? (EX. 2 blacks and 2 reds in one nipple and 2 whites and 2 blues in another).

    brian
    Reply to this comment

  • Can a panel be installed in a Janitor closet

    nasser Ahmed
    Reply to this comment

  • The questions and answers emails are very imformative and helpful. Keep them coming. Thanks.

    Mike
    Reply to this comment

  • The question Q8 on the protection of NM cable had a answer of, "EMT used to sleeve it for the purpose of physical protection must be grounded (bonded)". I though per article 250.86 exception #2 that short sectiions of raceways used for physical protection did not need grounded (Bonded).

    Joseph Amato
    Reply to this comment

  • You are 100% correct, but 334.15(C) has a specific requirement that when installed in unfinished basements, \"Metal conduit and tubings and metal outlet boxes shall be grounded.\" Unfortunatelly the changes to the text in the 2008 NEC states \"Metal conduit, tubing[s], and metal outlet boxes shall be connected to an equipment grounding con¬ductor. [ROP 7–58, 7–1, 7–63]\"

    I personally think that the text in 334.15(C) should be deleted and only the rules contained in Article 250 should apply, specifically 250.86 Ex2.

    Mike Holt
    Reply to this comment

  • Thank you posting the latest on the System bonding Jumper There has been alot of question about this and since I teach bonding and Grounding exclusively all the apprentices and journeyman come to me for answers Thank you again for helping be my best I am going on nine years in teaching this subject and have been a customer of yours for years. Journeyman IBEW Local 440 Riverside CA

    Laura Vergeront
    Reply to this comment

  • On Q5, besides the code says so, is this primarily the usual difference in Voltage ratings of signal wiring vs. power wiring? In machines, I have run signal wiring in 600V rated shielded cables alongside power wires, also in their own 600V rated shielded cables, and had no reliability impact and the NRTL gave it a thumbs up.

    Matt
    Reply to this comment

  • yes , having a debate,have always been told when running a single grounding wire thru metal pipe it causes induction unless you use a bonding bushing at end or ends of conduit..but i cannot find a rerference to this in the code book .?Am i correct and if so where is it in code book or is it?

    jim
    Reply to this comment

  • How do i get a hold of n en c questions and answers from previous months and part 1 for september ? please e-mail me with the answer ,,,THANK YOU

    Ricardo mota
    Reply to this comment


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