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tt system

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  1. Simon-0116

    Agricultural rcd tt system pannel board.

    Looking for recomendations for a pannel mccb board for a agricultural installation. Looking at schnider or protuse (city own brand). My understanding of 17th regs is as follows. Tt with a rod / plate or tn as long as plate laid in floor, under concrete. Then a 300ma s type main switch 4 pole...
  2. N

    TT System (411.5.1 - 18th)

    So the following has been added to this Regulation: 'The neutral point or midpoint of the power supply system shall be earthed. If a neutral point or midpoint is not available or not accessible, a line conductor shall be earthed.' I am assuming that in all TT earthing arrangements moving...
  3. TonyJohnson

    Can Metrel EasiTest carry out Earth Rod resistance test on TT System?

    Hi, I have a truck container cafe with a floating generator for power. I am fitting an earth spike to the generator and also an earth spike to the steel container. I then need to measure the TT system i have created but i only have a Metrel easitest.. Will the tester do the job and if so how do...
  4. A

    No ze at origin of tt system

    Hi guys, cannot get a resistance reading when using my Robin loop tester. It just shows 204v and the red do not proceed lamp lit. Never come across this before any ideas would be appreciated. (The live neutral reading is 243v) New rod fitted and driven in to good ground at about 2.3 meters.
  5. B

    Very strange RCD tripping problem on TT system. Need advice

    I'm in France and this is my first post, so apologies if this is in the wrong section. Here is the problem. I have a client, with a swimming pool and heat pump for the pool, but their main supply keeps tripping. The connection is: * Supply companies incoming feed, three-phase, limited to 30A...
  6. M

    TT system earth cable size.......

    Hi guys At a job doing a re wire and the electrician i was with is changing the earth cable over from 16mm to 6mm He says as its a tt system that it only needs a 6mm. Is this right?
  7. C

    Converting to a TT system... possibly

    1.25ohm external earth fault loop impedance on TN-S supply to building Supply authority stated our only option is a TT conversion as they will not covert to PME. What would be my best course of action when converting to a TT as the building is quite old and i do not want a 100ma main switch...
  8. andysparkfree

    100ma 100amp 3phase main switch on TT system and rcd protection on the rest of the circuits question

    Hi all , my question for your brilliant minds is (ill first set the scene) 35mm 4 core swa coming from an external supply, 16mm earth ran out to an earth rod(ze at the distribution board main switch 0.35ohms) now this is quite a large installation with a 3phase distribution board in the...
  9. Doomed

    TT system and gas bond

    Doing some bits for an old boy and checked the bonding, the gas bond does not go back to the DB or MET, but is staked right next to the main earth rod. I suppose it will effectively put the pipework in the same equipotential zone as the main earth, but just why make your life harder?
  10. P

    Rcbo's on a TT system

    Fitting rcbo's to a TT system using a Schneider distribution board I read the instructions to the rcbo's and it clearly states that they are not suitable for a TT system. I have not seen this on instructions to crabtree rcbo's and can only assume the issue is that when tripped the neutral is...
  11. C

    AMD 3 DB on a TT system

    Hello Guys being a Londoner i have not had a great deal of experience with TT systems in a domestic setting. The existing installation is in the basement, the existing earth rod is by the DB and sticking out of the ground, not inspection pit is that quite bad? I was thinking of changing the...
  12. S

    levels of rcd protection on TT system - long post - prepare cuppa first!

    Hi all, need some opinions on the following please> Origin is a three phase 60A TN-C-S supply.it goes into a changeover switch (small PTO driven generator across the yard) and then into a wylex three phase board. the incomer is 100A 4pole 100mA type S to provide discrimination to other...
  13. R

    Up front 100mA s type Rcd on a TT system.

    Hi all, Can anyone clarify whether it is O.k to remove a 100mA type s (time delay) Rcd which is upfront of a ammendment 3 splt load 30mA Rcd protected db, and replace it with a isolator? I can't seem to find a reference in the regs book. Any help would be great. Thanks.
  14. G

    Installing a TT system and marconite

    I will be helping on a install next week where we will be installing a TT system for a summer house in a garden, the customer has gone and bought a hot tub thing costing the same as a good van!. ( he should have waited Aldi are doing them for £399 in week or two) The house is a TNC-S set up and...
  15. S

    TT System 100ma S Type Housing

    Hi, Got a Domestic TT system which needs a new 100ma S Type RCD. What are your thoughts on this being placed in an Insulated or metal enclosure? It is not in an external meter cupboard so falls under 421.1.201 (within domestic). Thanks,
  16. M

    Enclosure For Rcd To Protect A Tt System, Have I Got This Right?

    Having a hard time figuring this one out, think I've got it but I figure best check with you guys! On a TT system, metal CU so needs to be protected by a time-delayed RCD in the tails (to allow smaller Amp RCDs on sections of the board to trip first), and this time-delayed RCD should be in it's...
  17. M

    TT system with kmf

    Hi, just looking for someone to confirm my plan is correct for a new installation, power is coming into the building from a 25mm2 single core SWA with armour as the neutral, that goes through 80A main fuse then through the meter. As the earthing is system, would I then need to run tails through...
  18. dnjr

    Dual rcd board tt system

    Dear all Wonder if anyone can enlighten me I've just changed a board to a dual rcd board. TT system with ze of 100 ohms All circuits test ok and everything fine for 2 days . Had a call to say that while the customer was out ( so nothing in use) both rcds tripped at same time , they know this as...
  19. rolyberkin

    Changing a TT system board - Best Practice

    Advice please I have been reading through the regs re a TT system consumer unit change and the onsite guide suggests at 2.2.6 a-c that consideration should be given to the board being either be class 2 board or class 1 with RCBO's or a split board with an S Type main RCD as isolator. The...
  20. C

    TT System RCD protection

    Hello electrical mafia, Just a quick one for you on this fine evening…..been asked to do the electrics for a hot tub install, house is a TT system and has no upfront RCD the ZE reading is 12 ohms. Would I be ok to split tails in a henley block and feed hot tub from a garage unit that has a 30ma...

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