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tt system

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  1. C

    TT System 400 Volts To Earth

    Hi all. First time on the forum, but have enjoyed reading many ofthe threads, thanks. I am looking for some advice on a fault from a TT systemand would greatly appreciate any input. History, my wife and I are volunteering in Africa for a fewyears. The charity I am helping does not have an...
  2. HappyHippyDad

    TT system - Why less than 200 π ?

    I have had a read through a few threads on a TT system needing to be below 200Ω and I wondered why the regulations state this figure? I dont mean why cant we just let it be higher (as it will be protected by an RCD - so in theory (not good practice) just needs to be below 1667Ω)), I mean why...
  3. A

    Megger 1730 ZS problem on TT system

    Doing a test with my 1730 for NAPIT inspection. Meter came up with CON which means connection problem. Thought that meter was playing up. Polarity was correct and the Ze was 83 ohms. Got City's to send out a brand new inbox 1730 did the same test with the same result CON. Can't be two meters...
  4. S

    tt system board change

    hi am i right in thinking on a board change for a tt system that the main 60a rccb can be done away with if installing a new plastic ccu with rcbos on all circuits? existing board is old brown wylex rewireable , no more room on board to facilitate new 10 kw shower circuit.thus board change...
  5. A

    TT System with no RCD

    Hello all here’s my first ever post. Quick background, I’ve been working for myself since theturn of the year building a portfolio, I have done a few minor works and a weekon Monday I will start a house rewire and wiring extension which I plan to useto be assessed on. I was asked from someone...
  6. R

    Is this a TT system ?

    Hi have to move a dis board and upgrade with new but confused a little bit Its in a urban area a 1920`s semi detached house but cant see any overhead lines at all I looked at the old school ELCB and thought TT , the main supply cable looks like old VR cable which is neatly clipped all round...
  7. M

    Question Tt system

    hi all wondered what your views on using split load board on Tt,explained to customer best option would be rcbos to cover 8 cuircuits only. gave her price oh that's to much !!! as long as ze below 200 ohms all good reg state all final circuits to be protected by rcd 30ma they will be. reg...
  8. B

    TT system

    Hi all again Just upgraded a domestic property today new consumer unit e.t.c now I've installed new earth spike with 16mm earth. Provided 30ma rcd protection for all final circuits, Ze readings are 25.2 ohms which is well below 200 ohms, Zs reAdings on final circuits are very high in the...
  9. M

    Max Ze for TT system

    Hi Gents and ladies, I have been asked to quote on installing a couple of extra socket on a TT system. When checking the existing installation my Zs readings on the ring are coming out at 39.8 Ohms (most remote). This is unacceptable (table 2d OSG). I then checked Ze readings which are...
  10. P

    Rented property, TT system, No RCD.

    Over 2 years ago a friend rented a house, After a brief look, the dangers were apparent. At the mains a TT system with small bonding cables, and no RCD just a Henley block fitted where the is a shadow mark the size of an old voltage operated trip, then rewireable fuses. Round the house every...
  11. L

    Hi help on a tt system with the board

    I'm an electrician but never work on tt systems , my girlfriends parents need some work doing and asked me to help . They currently have a board In switch a 100 am rcd but no main switch to isolate the board . Does the main switch have to be enclosed in the board or can it be in its own...
  12. 0

    Zs readings on TT system

    Hi there, In the process of testing a large property. TT system. Ra is 58.4 ohms so all good. But starting to test Zs and getting readings of 0.18 on sockets? Why would this be?
  13. B

    TT System High z's

    Testing a property with a TT system all circuits are reading a high figure for earth loop impediance,any suggestions done a rcd test on circuits the other day and it was not tripping at 1x but today is but at 5x meter is reading 25v.
  14. L

    Up-front RCD requirement -TT system.

    Hi, I have recently com across a job in which I have been asked to carry out some upgrading and various remedial work. It is a TT system and the tails from the meter to the consumer unit are run about 5 meters, under the floor, via a 60 a KMF located next to the meter. The consumer unit a...
  15. W

    TT system what set up would you use

    have to re wire an industrial unit and surrounding work shops but in two minds of how to install currently there is NO EARTH for the whole site, the place consists of a large storage shed with the mains coming in, TPN 100a supply, the place at the moment is a death trap no current RCD...
  16. C

    TT system help.

    Hi, I have a lad working on a farm at the moment and he phoned me today panicking at a high ZE and PSC. 3.50ohms and 79kA. I asked him what system was in place and he said TN-S. I then told him to go earth rod hunting. Got a phone call back saying he couldn't find anything. I'm on a course this...
  17. B

    RCDs in a tt system

    I recently installed a split board wylex consumer unit in a tt system that had been converted from a tns system by the provider about three years ago.The old system consisted of a consumer unit with old mini breakers only.When the system was changed to a tt the provider installed a 100Ma rcd...
  18. K

    ZS values on TT system

    I did a periodic and got some strange zs values. Can anybody explain these readings for me. Ze 14.1 Ring main r1 0.53 rn 0.53 r2 0.80 so r1+r2 = 0.33 measured zs came up with 30.3 Another ring main with very similar readings Lighting circuit ZS was 14.4 which is more like what I would expect to...
  19. R

    Backfed Earth on TT system

    Hi lads, Here's a good un . Went to a job this morning and lady has trouble with a steamer in the workshop . Got there and steamer is faulty causing RCD to trip in workshop and also voltage trip in house at same time , (garage unit RCD main switch), with an earth stake outside workshop...
  20. S

    tt system

    just done a new ring main on a tt system ..ze at source is 355..(r1+r2)= 1.3 ..measured zs at socket 296 still more than 200ohms recommended whos responsible for getting it lower me or the provider

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