Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16

Thread: 3 phase changeover

  1. #11
    Email problem Tonye's Avatar
    Join Date
    Mar 2015
    Location
    Pretoria
    Posts
    42
    Thanks
    0
    Thanked 11 Times in 8 Posts
    Hi SeanM, you are correct with regards neutral being switched.

  2. #12
    Email problem Tonye's Avatar
    Join Date
    Mar 2015
    Location
    Pretoria
    Posts
    42
    Thanks
    0
    Thanked 11 Times in 8 Posts
    7.12.2.4 Where the alternative supply is intended to provide a supply to an
    installation that is not connected to the main supply, or to provide a supply
    as a switched alternative to the main supply, the capacity and operating
    characteristics of the alternative supply shall be such that danger or damage
    to equipment does not arise after the connection or disconnection of any
    intended load
    as a result of the deviation of the voltage or frequency from the
    standard range. Means shall be provided to automatically disconnect such
    parts of the installation,
    as may be necessary if the capacity of the
    alternative supply is exceeded

    In one part they refer to any intended load & in the other they refer to the installation


    I think what is confusing here is the reference to parts of the installation

    It should read, where an alternate supply feeds an installation or part of an installation, Means shall be provided to automatically disconnect the installation or such part of the installation, as may be necessary if the capacity of the alternative supply is exceeded.

    This is how I interpret it

    Another thing is that Eskom ask people to manually turn off their geyser to avert Load shedding (exceeding their capacity)
    but supposedly this is not allowed when feeding from an alternate power supply

  3. #13
    Platinum Member
    Join Date
    Jun 2017
    Location
    Port Elizabeth
    Posts
    1,236
    Thanks
    34
    Thanked 304 Times in 258 Posts
    Quote Originally Posted by SeanM View Post
    Morning All

    I have a comment about automatic changeovers.

    The regulations clearly state that in a three phase installation all phases and neutral shall be switched with regards to alternative supplies I have yet to see any automatic changeovers do this.

    Referring specifically to generators , the 4 pole change over has been in the majority of Municipal bylaws for years and an Eskom bylaw .I found my 1991 application to register with Eskom as a contractor which stated 4 pole change over on all installations.
    The 4 Pole change over was written into SANS 10142-1 in 2003 and has also been there in the form of "you may not earth the neutral after the point of control". Sans 10142-1 clause 6.1.6

    Inverters/UPS do not need a change over switch but they do show a bypass switch - Nowhere do I find that a bypass switch shall be used - Seems like an optional

    But yet the supplies of change over switch inform me that here are more 3 pole switches sold then 4 pole. Shows you how many contractors/ consultants do not keep up to date .

  4. #14
    Platinum Member
    Join Date
    Jun 2017
    Location
    Port Elizabeth
    Posts
    1,236
    Thanks
    34
    Thanked 304 Times in 258 Posts
    Hi Tonye

    Would be interesting to hear other opinions on the clause 7.12.2.4

    The protection of the inverter output as a whole is covered under 7.12.5.1 - I see 7.12.2.4 as a requirement to prevent unnecessary tripping of the inverter and frustration prevention for the client.Same way that they suggest no more than 5KW per socket outlet circuit , but you can install 1 circuit for the complete installation.

    But lets forget regulations for a while and concentrate on logic.

    I go to the trouble of having a contractor install an inverter to make my life comfortable around load shedding.The last thing I want while I am at work,out of town, or enjoying a beer in the pub with mates is a call from my wife complaining that loadshedding is on and she is in darkness because the inverter has tripped .I will now have to spend time trying to talk her through switching circuits off. or - If I buy a house which has an inverter installed I may be that person that has absolutely no idea what a DB even looks like , will now sit through load shedding only to find part of my house come back on afterwards.

    The client today may not be the user tomorrow and as contractors we should be taking that into account.

    We have found the majority of Domestic clients want the same sort of set up usage mainly TV a light to be able to move around without falling over something, or a light for the kids to continue with home work.

    Where we have for some reason done domestic installations of inverters we have install a separate DB , with a circuit to the TV ,DSTV ,Hifi and router on a 10 amp or 5 amp CB , depending on equipment.
    We have also then installed a 5 amp or 10 amp CB to one light circuit , or rewire one circuit and installed LED.
    No change over and a seamless operation during load shedding , that the clients do not even realize that load shedding has begun while watching his favorite TV show.

    We have had some awkward clients that always refer to their mates that have complete house running on 2 batteries etc etc. After 2 or 3 months those mates have contacted us as the frustration levels have increased with loadshedding , battery failure , inverter failure etc. and they now also want to just sit back and watch tv without getting up to switch things off especially when they have been out and the kids/wife have forgotten to switch items off and overloaded the system constantly .

  5. #15
    New Member
    Join Date
    Oct 2022
    Location
    gauteng
    Posts
    1
    Thanks
    0
    Thanked 0 Times in 0 Posts
    This is an old thread, im shocked to see a Mecer ups integrated into a DB. i see no earth spike wiring, i could just assume that neutrals in this install are common across the utility and inverter.

    an earth neutral bond is essential for circuits connected to the inverter in conjunction with a RCD on the inverter output after the bond.

    the changeover switch effectively disconnects the earth bond on the utility side, hence a separate bond is not only allowed but a requirement to be compliant with SANS10142

    i hope this has been corrected since this photo was posted as you have effectively removed the protective shell around everything connected to the inverter

  6. #16
    Platinum Member
    Join Date
    Mar 2022
    Location
    South Africa
    Posts
    1,987
    Thanks
    55
    Thanked 93 Times in 89 Posts
    Quote Originally Posted by phillip87 View Post
    This is an old thread, im shocked to see a Mecer ups integrated into a DB. i see no earth spike wiring, i could just assume that neutrals in this install are common across the utility and inverter.

    an earth neutral bond is essential for circuits connected to the inverter in conjunction with a RCD on the inverter output after the bond.

    the changeover switch effectively disconnects the earth bond on the utility side, hence a separate bond is not only allowed but a requirement to be compliant with SANS10142

    i hope this has been corrected since this photo was posted as you have effectively removed the protective shell around everything connected to the inverter

    I am shocked to see 99 percent of pictures being posted on social media.

    Please attach the code or which SANS and the page.

Page 2 of 2 FirstFirst 12

Similar Threads

  1. How to CoC a changeover switch??
    By deejaypsy in forum Electrical Contracting Industry Forum
    Replies: 39
    Last Post: 08-Mar-20, 06:02 AM
  2. Single phase generator feeding 1 phase of 3 phase db - discuss.
    By skatingsparks in forum Electrical Contracting Industry Forum
    Replies: 6
    Last Post: 03-Jul-18, 10:06 AM
  3. [Question] Changeover switch
    By Clive287 in forum Electrical Contracting Industry Forum
    Replies: 3
    Last Post: 03-Nov-16, 07:00 AM
  4. Three phase to single phase generator advice needed
    By joshthejew in forum Electrical Contracting Industry Forum
    Replies: 3
    Last Post: 08-Apr-15, 10:12 PM
  5. [Question] Single phase and 3 phase testing course
    By skatingsparks in forum Electrical Contracting Industry Forum
    Replies: 3
    Last Post: 26-Feb-09, 09:14 AM

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

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