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    240.21c

    Per 240.21c, do we need an ocpd between tr and secondary conductors?
    "Sleem"

    #2
    Any feedback!
    "Sleem"

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      #3
      It would help to know distance and whether this is outside, inside or both. Does the MDP have a main????
      They say I shot a man named Gray and took his wife to Italy
      She inherited a million bucks and when she died it came to me
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        #4
        In addition,, keep in mind =your "240." Code reference may not the the most applicable.
        Where is the service point ? If that is a POCO transformer (or customer) you may be dealing with Art 230 rules rather than Art 240.
        At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

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          #5
          Originally posted by augie47 View Post
          In addition,, keep in mind =your "240." Code reference may not the the most applicable.
          Where is the service point ? If that is a POCO transformer (or customer) you may be dealing with Art 230 rules rather than Art 240.
          I agree to apply the NEC here we need to define the service point as defined in article 100.
          And we need to know where the conductors are located, inside the building or outside etc.

          m sleem Your in Egypt right?
          Does the Ministry of Electricity recognize the NFPA 70 NEC as an acceptable standard? Have they amended it? (I would love to see a copy.) Or does you, your firm or your client just prefer to use the NEC?
          And what version are you on?
          I see your dealing with a three phase 50hz 13.5kV delta to 400Y230 system, such a system is not in the stock NEC yet.
          With the 'minimum product standards' being deleted from the code and replaced with requiring more and more 'listed' equipment you probably will find it hard to implement the code as its intended, unless your using all North American products for some reason.
          Comments based on 2017 NEC unless otherwise noted.

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            #6
            Originally posted by Dennis Alwon View Post
            It would help to know distance and whether this is outside, inside or both. Does the MDP have a main????
            Distance = 30 m
            inside building
            MDP has main OCPD
            "Sleem"

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              #7
              Originally posted by augie47 View Post
              In addition,, keep in mind =your "240." Code reference may not the the most applicable.
              Where is the service point ? If that is a POCO transformer (or customer) you may be dealing with Art 230 rules rather than Art 240.
              It's Customer transformer not POCO
              "Sleem"

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                #8
                Originally posted by tortuga View Post
                I agree to apply the NEC here we need to define the service point as defined in article 100.
                And we need to know where the conductors are located, inside the building or outside etc.

                m sleem Your in Egypt right?
                Does the Ministry of Electricity recognize the NFPA 70 NEC as an acceptable standard? Have they amended it? (I would love to see a copy.) Or does you, your firm or your client just prefer to use the NEC?
                And what version are you on?
                I see your dealing with a three phase 50hz 13.5kV delta to 400Y230 system, such a system is not in the stock NEC yet.
                With the 'minimum product standards' being deleted from the code and replaced with requiring more and more 'listed' equipment you probably will find it hard to implement the code as its intended, unless your using all North American products for some reason.
                Yes, i am in Egypt but i am dealing with project outside where NEC is followed.
                "Sleem"

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                  #9
                  Originally posted by m sleem View Post
                  It's Customer transformer not POCO
                  Where is it metered? On the primary side?
                  Check out Table 450.3(A).
                  Whats the primary protection size and type (breaker or fuse?)
                  Whats the transformer rated current?
                  Or do you get to specify all that?
                  Originally posted by m sleem View Post
                  Yes, i am in Egypt but i am dealing with project outside where NEC is followed.
                  Cool

                  I haven't done many 400Y230 systems under the NEC.
                  Comments based on 2017 NEC unless otherwise noted.

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                    #10
                    Originally posted by m sleem View Post
                    Per 240.21c, do we need an ocpd between tr and secondary conductors?
                    240.21(C) would require an OCPD within 7.5m secondary conductor length.

                    You may be able to use the 100m secondary conductor length per 240.92(C) if the installation is in a Supervised Industrial Installation.

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                      #11
                      Originally posted by m sleem View Post
                      It's Customer transformer not POCO
                      Where is "service point"? Customer may have to pay for the transformer even if it is on utility side of the service point, but doesn't necessarily mean they actually own it.

                      If this is on customer side of service point then you should have a "service disconnect" on the supply side somewhere (possibly what you identify as ACP). Then 240.21(C) applies to the conductors between the transformer and the first overcurrent device. Generally it isn't a question of whether you need overcurrent protection but rather how close does it need to be to the source and what ampacity must the conductors be, different conditions allow for variances here.
                      I live for today, I'm just a day behind.

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                        #12
                        My guess this is a situation where the power is arranged in bulk at 13.5 into a 'campus' that the POCO has limited or no access to, typically the first primary cutouts to the 'campus' are the service point. Then the feeders are run around to different buildings at 13.5.
                        Comments based on 2017 NEC unless otherwise noted.

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                          #13
                          Originally posted by david luchini View Post
                          240.21(C) would require an OCPD within 7.5m secondary conductor length.

                          You may be able to use the 100m secondary conductor length per 240.92(C) if the installation is in a Supervised Industrial Installation.
                          Originally posted by david luchini View Post
                          240.21(C) would require an OCPD within 7.5m secondary conductor length.
                          Having ocpd between tr's secondary and conductors is not a common practice at least in our places, also conductors would be protected against short circuit by tr's primary ocpd, and it would be protected against overload by MDP main ocpd.
                          "Sleem"

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                            #14
                            Originally posted by m sleem View Post
                            Having ocpd between tr's secondary and conductors is not a common practice at least in our places, also conductors would be protected against short circuit by tr's primary ocpd, and it would be protected against overload by MDP main ocpd.
                            Which is what happens with service conductors in otherwise NEC compliant applications, but you haven't made it clear exactly whether you are dealing with service conductors or secondary conductors of a separately derived system - per how NEC would apply.

                            Per NEC any service conductor coming into the building should have overcurrent protection at or near point of entrance, how close isn't really specified and varies from one AHJ to another. Non service conductors sort of apply similar rule but because there usually is overcurrent protection of some sort on other than service conductors rules can vary some. Still any feeder conductor/transformer secondary conductor that is not protected at or below it's ampacity is essentially subject to 240.21 (B) or (C).
                            I live for today, I'm just a day behind.

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                              #15
                              Originally posted by kwired View Post
                              Which is what happens with service conductors in otherwise NEC compliant applications, but you haven't made it clear exactly whether you are dealing with service conductors or secondary conductors of a separately derived system - per how NEC would apply.
                              yes, iam dealing with service conductors.
                              "Sleem"

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