Page 1 of 2 12 LastLast
Results 1 to 10 of 13

Thread: Strange Earth Leakage issue

  1. #1
    Full Member
    Join Date
    Mar 2013
    Location
    KZN
    Posts
    61
    Thanks
    0
    Thanked 0 Times in 0 Posts

    Strange Earth Leakage issue

    Hi Fellow Electricians, I need some advice with an issue I've never encountered before.
    The customer is building an addition to his out building requested that the sub db have it's own earth leakage and taken off from the earth leakage in the main db at the house. So we did this. This sub db has 5 plugs and 3 lights and a swimming pool db. the lights are not on earth leakage. so this is where it gets interesting. When we switched the power on the lights, plugs and pool was working fine until a couple minutes later, the earth leakage in the sub db tripped. The time it takes to trip varies and when I Meggered each circuit between live/neutral/earth, I did not pick up any fault. It sometimes trippes after 2 minutes and sometimes after 20minutes. It seems to happen when the pool is running as nothing else is plugged in. But when I bypassed the earth leakage in the sub db and put the supply cable to the sub db back on to earth leakage at the main db and funny enough, it never tripped out again. the house earth leakage trippes on 20mA with the plug tester and the one I had in the Sub DB tripped at 30mA and I also changed the earth leakage twice. Any Advice on why it trippes at the sub db's earth leakage and not on the earth leakage at the main db in the house?

  2. #2
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    2,671
    Thanks
    88
    Thanked 544 Times in 460 Posts
    Blog Entries
    1
    A neutral connection problem?
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

  3. #3
    Full Member
    Join Date
    Mar 2013
    Location
    KZN
    Posts
    61
    Thanks
    0
    Thanked 0 Times in 0 Posts
    How so?

  4. #4
    Diamond Member Justloadit's Avatar
    Join Date
    Nov 2010
    Location
    Johannesburg
    Posts
    2,671
    Thanks
    88
    Thanked 544 Times in 460 Posts
    Blog Entries
    1
    If the Neutral is not correctly wired in the secondary DB, any current flow will be unbalanced and the ELB will trip.
    Alternatively there is a Neutral to earth fault some where, which will also cause an earth fault. This fault could be due to humidity or insects
    Victor - Knowledge is a blessing or a curse, your current circumstances make you decide!
    Solar and LED lighting solutions - www.microsolve.co.za

  5. #5
    Diamond Member AndyD's Avatar
    Join Date
    Jan 2010
    Location
    Cape Town
    Posts
    4,400
    Thanks
    513
    Thanked 854 Times in 687 Posts
    A crossed nuetral will usually cause an immediate RCD trip. With a fault that takes a few minutes to trip you're better monitoring the leakage over time with an earth leakage clamp meter clamped around the L+N simultaneously. This has the advantage of letting you run everything and monitor the leakage under normal operating conditions rather than the megger which gives a result whilst nothing is running.
    _______________________________________________
    I am special and so is Vanash.
    _______________________________________________

  6. Thanks given for this post:

    ACEsterhuizen (27-Jul-14)

  7. #6
    Full Member
    Join Date
    Mar 2013
    Location
    KZN
    Posts
    61
    Thanks
    0
    Thanked 0 Times in 0 Posts
    That's an interesting point. I googled this tester and will get it and try it out. Thanx

  8. #7
    Full Member
    Join Date
    Jan 2014
    Location
    Orkney
    Posts
    32
    Thanks
    5
    Thanked 4 Times in 4 Posts
    Quote Originally Posted by Pieter00 View Post
    The customer is building an addition to his out building requested that the sub db have it's own earth leakage and taken off from the earth leakage in the main db at the house.
    Just a quick question with the above statement... Is the sub db's supply cable taken from above or below the main db's earth leakage?

  9. #8
    Full Member
    Join Date
    Mar 2013
    Location
    KZN
    Posts
    61
    Thanks
    0
    Thanked 0 Times in 0 Posts
    It was taken above the earth leakage of the main DB and was put back under the earth leakage in the main db and then the earth leakage stopped tripping

  10. #9
    Silver Member
    Join Date
    Sep 2010
    Location
    cape town
    Posts
    297
    Thanks
    3
    Thanked 42 Times in 36 Posts
    i also think its an incorrect neutral connection in the sub db. when you reconnected the sub db to the earth leakage relay in the main db and bypassed it in the sub db,then there is no more neutral fault in the sub db as both neutral bars (in the sub db) become one.
    also i have found it when i have made that same mistake i have tested with the plug tester ,the earth leakage relay trips fine,but once you plug in a load the e/l trips.
    willing to wager

  11. #10
    Full Member
    Join Date
    Mar 2013
    Location
    KZN
    Posts
    61
    Thanks
    0
    Thanked 0 Times in 0 Posts
    The supply cable is not on earth leakage at the main db and also not on the sub db. If there was a neutral fault on the circuit the earth leakage would trip as soon as it carries load. It's not tripping as soon as there's load but trips in a couple of minutes, always different times. A neutral fault does operate like this

Page 1 of 2 12 LastLast

Similar Threads

  1. Geyser not on earth leakage
    By Goobie in forum Electrical Contracting Industry Forum
    Replies: 11
    Last Post: 07-Dec-17, 12:40 PM
  2. Does a stove need to be on an earth leakage?
    By Leecatt in forum Electrical Contracting Industry Forum
    Replies: 48
    Last Post: 12-Oct-17, 08:36 AM
  3. Earth Leakage
    By Pieter00 in forum Electrical Contracting Industry Forum
    Replies: 13
    Last Post: 27-May-13, 12:03 PM
  4. Earth leakage trips at night??
    By Jongseun in forum Electrical Contracting Industry Forum
    Replies: 18
    Last Post: 18-Jun-12, 10:47 PM
  5. CBI earth leakage units
    By murdock in forum Electrical Contracting Industry Forum
    Replies: 2
    Last Post: 29-Oct-09, 12:44 PM

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
  •