Page 1 of 2 12 LastLast
Results 1 to 10 of 18

Thread: Class 1 Div 2

  1. #1
    Join Date
    Aug 2010
    Posts
    15

    Class 1 Div 2

    have a small wheeled skid....Class 1 Div2......XP enclosure with motor starter, xp motor. Motor is within 2ft of enclosure.....original wiring had a single seal at the enclosure, then xp flexible sealtight, into the motor connection box mounted on the motor (also xp).....question.....do I need a sealoff at both ends of the flexible sealtight? Actual length of the flexible may only be 18" or less.
    Thanks, Bob

  2. #2
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,070
    The important question is whether the motor was/is required to be explosionproof; it is possible for single phase motors, not likely for three phase.

    If is required, it still sounds like it is ok if? the explosionproof flexible fitting (technically it's an explosinproof flexible coupling) is less than 18".
    Last edited by rbalex; 09-08-13 at 10:59 PM.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  3. #3
    Join Date
    Aug 2010
    Posts
    15

    XP Motor

    Understand if the coupling is less than 18".....

    Not sure I understand the first part of your reply.....are you stating a 3ph motor wouldn't need to be xp, or a 1p motor wouldn't need to be....or something else entirely?

    thanks, bob

  4. #4
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,070
    In Class I, Division 2 motors, are not always required to be explosionproof. Most 3 phase motors aren't required to be; most single phase motors are. See Section 501.125(B)
    Last edited by rbalex; 09-09-13 at 12:59 AM.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  5. #5
    Join Date
    Aug 2010
    Posts
    15

    Incoming

    two last questions and then I'll leave everyone alone......
    Appleton motor starter on a wheeled skid......the incoming power is a cable with an Appleton plug connected to the motor started through a sealoff.......is the sealoff necessary?
    second question.....I was always under the impression that all the threaded connections required sealant.....I've seen some other posts that indicate you should not seal the threads?
    thanks, bob

  6. #6
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,070
    A seal is required for the explosionproof? starter.

    Conduit sealant is neither required nor prohibited, but I don't recommend it if it is installed as required by Section 500.8(E).
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  7. #7
    Join Date
    Aug 2010
    Posts
    15

    XP

    Yes....its an Appleton XP starter.....I was under the impression (most likely false) that the sealoff was to prevent an explosive front from propagating down through a conduit run (or out of a classified area)....not to prevent vapors from entering the enclosure itself....since there is no conduit I simply posed the question....and I will read sections you referenced in your replies this weekend.

    Many Thanks,

  8. #8
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,070
    Quote Originally Posted by rswolff001 View Post
    Yes....its an Appleton XP starter.....I was under the impression (most likely false) that the sealoff was to prevent an explosive front from propagating down through a conduit run (or out of a classified area)....not to prevent vapors from entering the enclosure itself....since there is no conduit I simply posed the question....and I will read sections you referenced in your replies this weekend.

    Many Thanks,
    Your impression is correct. The seal is to prevent an explosive front from propagating down through a conduit run from an explosion initiated in the starter. Explosionproof (Type 7) enclosures "breathe" and it is not unusual for gasses and vapors to concentrate in them.

    In fact, seals don't prevent the entry of Class I flammable materials either. This bit of information should be in Section 501.15(C); however it is found in the last sentences of 501.15(E)(2) and (3). This is especially bad since no one has ever manufactured a 501.15(E)(2) cable.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  9. #9
    Join Date
    Aug 2010
    Posts
    15

    One last (really) question

    Same application.....coming out of the motor control we have a cord with an XP plug....there is a sealoff at the motor control that the cord will pass thru.....is there a specific type of cord grip on the outgoing (cable side) of the sealoff that needs to be used.....I can't find a specific reference to it but bear with me....I only learned to read recently.......
    thanks, bob

    and to understand what someone has said....it always helps if they understand what they wanted to say in the first place..........

  10. #10
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,070
    The "fundamentals" of flexible cords is found in Section 501.140. Of particular interest to you will be Subsections 501.140(A), 501.140(B)(3)-(5).
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •