discrimination

  1. D

    Discrimination

    First post - Go easy! Advice please - suggestions/best practice. Domestic property, TNCS supply, 25mm tails to RCBO C/U with 100A main switch. I want to install a distribution circuit from the aforementioned C/U (I dont want to split tails) to supply a second RCBO C/U (essentially a garage...
  2. Bluetit

    TT sub mains and discrimination..

    Hi, Just a quick sanity check really around rcbo discrimination.. but also RCDs being used as L-E fault protection. Scenario being a garage board change. Setup is: garage sub main fed from a main house CU. Initially wired in 10mm t&e with a 10mm earth along side it, run entirely in the ceiling...
  3. V

    EICR code for lack of discrimination between RCD's

    Hi all Called to do an EICR on a property 4 studio flats / bedsits within a single house. The t&e sub main to each flat runs within the fabric of the building and has a 30mA RCD at its distribution point...assuming this was an add on to the original installation. Each flat has a RCD main...
  4. Rockingit

    Suggestions for better RCD discrimination

    Have an existing old client with what's best described as a sprawling small-holding of a property. There's an armoured external supply which branches into a submain for various sheds/workshops/stables (some of which are 150-200m) etc all of which have standard RCD final circuit protection and...
  5. L

    Discrimination to sub board

    Sorry if this is obvious but I thought discrimination was for down stream? I want to feed and outdoor unit which only requires 6am and 16amp, it has a little sub board with these breakers but a 100a main switch, my supply is a 32a commando outlet. Should I feed existing sub board with existing...
  6. johnwicklover

    Carrying out a refurb on old panel boards, worried about discrimination.

    I am carrying out a refurbishment job on this old panel board and fitting in a new panel board from Schneider. The current supply to this building is a 100amps BS88-2 Gg (assuming). I am planning to protect the outgoing submains with the NSX100 ML 2.2 set at 100 and 63 respectively. I don't know...
  7. timbobelfast

    Discrimination Study

    Can anybody explain the discrimination overlaps in the attached protection study? For example, a Live to earth fault in the downstream OCPD and how this may play out. I know the current settings are not ideal, but this is a legacy issue restricted by cable sizes etc!
  8. Designmen90

    Discrimination and cascading

    Well, I'm a little bit confused :rolleyes: I have two circuit breakers, upstream CB is NSX630F (36kA Icu at 380/415 VAC 50/60), while downstream is IC60N (10kA Icu 220...240 VAC 50/60). They are in total dicrimination, BUT - IC60N cannot operete in cascading mode with NSX630F. WTF? o_O
  9. HappyHippyDad

    Achieving selectivity from 30mA?

    My customer has some garden pole lights up his driveway, they occasionally trip one of the RCD's in his dual RCD baord (once every 1-2 years). I will fix the problem but they are in such a poor position that I feel it may happen again in a year or 2. They are simply plugged in to a socket in...
  10. C

    Electrical Discrimination Issues

    I have an electrical installation in a garage. The supply from the house to the garage is protected by a 80 Amp 100mA RCD. When I use certain tools in the garage, mainly an orbital sander and a finger grinder the main RCD in the house trips and plunges the place into darkness, seemingly by...
  11. N

    No Discrimination

    Evening guys, Query with discrimination. Main DB with 30m/A RCD feeding another sub board with 30m\A RCD. The RCD in the main DB is tripping out before the sub board RCD. Am I able to change the Main DB RCD to a type S? (All that Main RCD is feeding is two sub boards, twin and earth fed in an...
  12. B

    no discrimination in sockets & lights

    I have came across a problem where the sockets and lights are run on a same circuit and it's done in a way where the person have put probably junction boxes in the walls which are not accessible and only 1 cable is coming to sockets , light switches and lights. I can't put fcu to discriminate as...
  13. N

    Instantaneous faults and discrimination

    Hi, I am currently working on a project where the client has asked us to complete a discrimination study. The primary area of concern involves an upstream miniature circuit breaker (25A type C) and a downstream 10A gG fuse. The type C circuit breaker time current characteristics within BS...
  14. B

    Rcd discrimination on circuit

    Hi, I’m installing some caravan boxes with 32A socket which is protected by 32A 30ma RCBO inside the box and then plug and play 32A socket inside the caravan to consumer unit which has main switch and RCD circuits can some on explain the discrimination please?
  15. Ian1981

    Discrimination charts for square D/Schneider

    Has anyone got any decent discrimination charts for square D/ Schneider mcbs? What I want to know is at what point might I achieve discrimination of some description between a 63 amp type C upstream device and a 32 amp type B downstream device. Zs for the sockets on the type B was 0.53 ohms...
  16. Michaelwgroves

    Using Type D MCB for discrimination

    I've just been on phone with Hager designing domestic distribution board design. Engineer advised using Type D 63A in distribution board supplying CU to give better discrimination. Looking at tables anything over 10A on CU might also trip Type D, but it does give a better chance. So I need to...
  17. Soulsurfer

    MCB discrimination ...

    Hey I had a callout referred by a lad working for me yesterday where one of the old dimplex CXL I think it is storage heater with an on peak convector heater built in had a fault and took out the property supply. He had attended the call and said that the B16 Hager at the board had not tripped...
  18. C

    Garage Board - achieving discrimination?

    Hi all, New to the forum so thanks in advance for your help. I've just fitted a garage board details below: Main Consumer Unit is Dual RCD - whoever did the re-wire had already fitted 6mm t&e direct from cu into an external jb. I've connected the t&e to swa (house end) and at the garage end...
    • CraigL
    • Thread
    • board discrimination garage
    • Replies: 93
    • Forum: UK Electrical Forum
  19. joebell25

    Discrimination headache!!!

    Thought I'd try out this ElectricalOM software for a new installation I'm designing. However come up with abit of an issue with the discrimination on 2 of the devices. Single phase sub feed from DB2 (60898 type c 63A 10kA) to DB3, Final circuit from DB3 (61009 30mA 32A type c 10kA RCBO) Time v...
  20. T

    3 phase distribution

    Hi all, Just an enquiry.. Our company have recently moved factory's. I am talking a very small unit. At the moment there is one TPN distribution board which is at the top end of the factory.. Is there any problem running a 3 phase supply off a 63amp mcb which will feed the new d/b just to keep...
    • Tom Ashcroft
    • Thread
    • 3 phase discrimination distribution existing phase supply switch
    • Replies: 16
    • Forum: Talk Electrician Forum
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