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  1. P

    Upstream RCD's

    Hi all, I am currently planning on designing an installation for a conservatory to be fitted with lights, floor sockets, and underfloor heating. My plan was to take a 6mm T+E from the Hager consumer unit under the stairs, protected at 32A, which would then run above the ceiling of the room...
  2. DmackG

    Electrical Installations in Schools

    I have been trying in vain to identify whether there is or indeed has been, specific wiring regulations for schools/colleges or universities. eg New Zealand Ministry of Education have an "Electrical Installations: Standard for Schools" in which they state the requirement for all sockets to have...
  3. A

    Random RCD's tripping

    Hi to everyone, I'm new on the forum and a almost a new in this world too. I got my full qualifications done in April but never done any job yet. So I'll try to explain the situation in the best way I can 3 double light holder on the outside of a wall are on a single way switch. The switch is...
  4. G

    Type A and AC RCD's

    Just watched an interesting sparkyninja video called "should we just stop using type AC RCD's?" highlighting the issues in using them, and the slightly ambiguous phrasing used in bs7671. Just wondered what others thought about it, and what if anything you were doing?
  5. gazdkw82

    Numerous RCD's, selectivity

    Looking for a little advice. I was speaking with a colleague who was confused about a circuit design that doesn't offer much selectivity. A sub main is being fed via a SWA to a 63A commando style outlet which is to be used for temporary set ups (shows, Marquess etc). The circuit is protected...
  6. rolyberkin

    RCBO Test data - 40 milliseconds

    Okay may be a thick question but I have an RCD tripping on 5 x test 180 at 40ms. Pass or fail? GN3 says must not exceed 40ms BBB says within 40ms My tester says computer says no. To be honest I am recommending it be changed anyway but it will be a call back on a new build for another spark so...
  7. V

    EICR and RCD's. Is it a C2 or C3?

    Hi, My EICR is a C2 because the consumer unit does NOT have RCD's. Is it correct? My last EICR five years ago stated RCD as recommended. What's changed? The flat is on the 2nd floor built in 1997! The electrician has quoted for a NEW Consumer Unit. Thanks Victor
  8. happyhippydad

    Understanding 411.3.4, RCD's for lights.

    I just wanted to make sure I understood the new regulation above. I am about to replace some ELV downlights with mains voltage, do these now have to be 30mA RCD protected? At present they have 100mA protection and the earthing is TT. Cheers.
  9. C

    MK time delayed rcd's?

    I asked my wholesaler for one today only to be told they're discontinued. A quick google of MK 6400s seems to confirm this. Does anyone know why this is and if Mk are producing a new version for some reason?
  10. D

    Both RCD's trip randomly

    Scratching my head a bit on a job today. Been to clients house to investigate fault with installation. For the past few months client has reported that both RCD's on his dual RCD board have tripped at the same time on odd occasions thus losing all power to house. House was rewired by another...
  11. leep82

    RCD's in series and how to test

    Im currently working on a site where im testing the supplies to the site cabins. Each cabin has its own 6 way single phase DB with a double pole RCD as a main switch. The DB's are then fed via commando plug and socket arrangement from a 32a RCBO within a TP&N DB. When the cabins were originally...
  12. W

    Rcds not tripping at 50ms now

    Hello I've got a rcd It trips at 1 times okay but gets greater than 50ms at 5x on one cycle but it's okay on the other cycle on three rcbos out of 5 it's not the circuit I've swapped over the cable what's that mean what will happen
  13. Dannyg8810

    16amp 230 3pin sockets and rcd's

    Just want other people's opinions on this In a warehouse were 16amp sockets are used for conveyors only would these need to be installed with rcbo's or just an mcb?
  14. S

    For sale: Main isolators, RCD's, RCBO's, MCB's ...

    Hi all, A am selling some Main isolators, RCD's, RCBO's, MCB's and some other stuff as seen on the picture. Most of the items brand new, some have served as display but never used. PM me if interested, so I can send a list with all items. The ideal situation will be if someone wants to buy...
  15. U

    Old regs

    Hi all. Chatting with a friend earlier on and he happened to mention that his house has no RCD protection. Now this is an old house, he has never had any work done on it as far as I am aware of in the last 35 years. he owns the property but originally it was council owned. I am astonished that...
  16. P

    French wiring book showing Type AC 40a breaker with N and L wired opposite

    Hi all. I've just had my house in France upgraded to single phase. I've bought a consumer unit as i only want a basic set up (minimal electric is used in my house!) and am going to put it in myself. I have a book which teaches you how to wire up. The consumer unit comes pre-packed with one...
  17. V

    Rcd's that fail to operate in less than 40 m/s

    Hi All Ok...after many years of testing rcd trip times...having some failed or faulty rcd's....we are starting to come across perfectly good rcds / rcbo's . .from various makes....that wont trip at all..or wont trip in under 40 m/s. about a year a domestic property..we fitted a new...
  18. M

    Rcd query.........??

    Hi Guys, does anybody know what the fundemental difference is between a type 1 rcd in relation to a normal domestic type to bs 61008. These have been mentioned for supplies to electric vehicle chargers....? Many thanks in advance ))
  19. dlt27

    High zs on RCD's.

    Hi all. I carried out an EICR yesterday. It was a BG split load consumer unit and when testing I noticed the zs values were coming out high. I noticed on the 1 rcd there was 0.50 Ohms difference between feed and load side of rcd and on rcd 2 there was 0.60 Ohms difference. Just wondered if...
  20. R

    Condition report for the old installations

    I have to do a Condition Report for an old installation. Everything is ok but the installation doesn't have RCD's, even for those circuits required by the 17th Edition. Can I write that the installation is "satisfactory" without RCD's ?
  21. Sparky_Steve

    red tab in crabtree starbreaker busbar

    I have a metal clad crabtree starbreaker board which i'm planning on using rcbos with how do you remove the red tab?
  22. M

    Industrial Harmonics and tripping RCD

    I have just completed an installation on a fruit farm which all tested 100%. There are 3 x 3 phase pumps 32a 41a & 41a, only 2 run together at an one time. When the second pump is started the 100A 100mA trips out. The pumps are run from variable speed controllers on a three wire system, no...
  23. F

    480VAC MCB & RCD required

    I'm doing some electrical work for a firm that is building some equipment to be installed for a client in Canada. The minimum rating of the 3 phase MCB's and RCD's need to be minimum 480 VAC Any names of manufacturers that provide MCB's or RCD's to operate to 480 VAC would be much appreciated...
  24. S

    high integrity board layout - Is this Ok?

    Hi, I have looked inside my Dad's Consumer Unit and I noticed that it has 2 RCD's but also 1 RCBO. I've seen these before but on my dads I was worried that it has to many (live) terminations into the bottom of the main switch? It has the usual 2 live conductors (wires) in it each going off to...
  25. P

    agricultural building

    Assistance please anyone with a reg book (can't find mine, may have to empty van in morning) supply is TT from meter into 4 pole RCD is it 300mA ? this is supplying via two fused switch in swa two separate fuse boards one single phase one three phase Question all socket outlets on 30mA but...
  26. F

    nominal current rating of main switch

    hi guys if installing a shower consumer unit with a 63amp rcd main switch and a 100 amp OPD PRIMARY SUPPLY then main switch is of a lesser value than the main over current protective device how do we get around this.
  27. D


    I have a strange fault. I have a split board. 2 rcd's. One keeps tripping but other is fine. I swapped them both and the same happened with the RCD I put in the place of the first one. Rcd's seem to be fine but when installed in that position they trip but are fine when in the other side...
  28. T

    240v on the neutral ??

    why am i finding 240v on the neutral ?? we rewired the power in a house and upgraded the consumer unit but when the RCD's are connected they trip different mcb's. when testing we found 240v on the neutral.... when you take away the RCD's everything is fine. we have changed the main switch and...
  29. telectrix

    RCDs and the Importance of the Test Button.

    done a small job today. just a socket & SFCU ( for a light) in customer's shed, on existing feed. feed cable is 2.5mm on a 16A MCB, RCD protected. cable tested OK, installed bits. Zs 2.4Ω. ramp test of RCD, mft reads>51mS. prerssed test button on RCD (which the customer said had never been done...
  30. T


    Morning. What is the reason for having a 100ma rcd as a main switch on a tt system instead of 30ma
  31. DaveyD

    100mA delayed RCD tripping before the 30mA at DB. TT System

    Hello Just not on the job at the moment but the builder called. He plugged his small angle grinder in to a new circuit and it took out the RCD at the supplying DB not the 30mA at local CU. Here's the set up: TT . 100A DNO fuse House CU old and full so split tails into small CU with...
  32. F

    time delay rcds

    were would you use a time delay rcd and what are the benefits of doing so is it just in tt installations
  33. H

    Questions about RCD's

    Helllo all, Just a question about the operation of RCD's At work there is 8 containers all fed from a panel. Each container is assigned a 132A RCD from this panel. The feeder units in each container have RCD's for lights, sockets & heaters ect. When I was fitting some new sockets into one of...
  34. F

    Cheap RCD's - will a crimp tool help

    Hi All I come across a number of cheap RCD's where you can pull the feed wires out (10mm or 16mm - H07VR). Put the wires back in, tighten the screws so that the heads start to break up, wait a few minutes and you can then wiggle the wires out again. I think that the problem is that the cable...
  35. jibjob

    Unusual RCD problem

    Here's the senario. Regency building with 5 flats contained within. System is 3 Phase with a further 2 service fuses added on making 5 in total, earthing is TT. Each flat is fed via a mixture of DP 100mA or 30mA RCD's which in turn feed KMF switched fuse isolators. 16mm T&E tails to each flat...
  36. A

    Domestic Help please rcd does not trip.

    Hi folks I have just installed an new mk consumer unit, but I'm having problem with the 63A rcd's. The test button works fine and it does not trip @ x1/2 it trips at 99.0 @ x1 and fails to trip @ x5 (>40ms) Its not the tester as I've checked it on another installation I know to be good. Any...
  37. La Poste

    Most reliable RCD brand.

    Greetings. There has been much talk of the unreliability of RCD's lately so I was wondering what are peoples thoughts on the most reliable. Do you have a favourite brand? What do you think is the worst brand? I am hearing quite good things about MK brand but they are quite pricey. Thanks.
  38. K

    3 63 amp RCDs on same circiut

    2 are in the board and the other is feeding that which is also being fed from a 100 amp rcd. cant seem to find any problems with cables and does just nuisance trip. help plz
  39. La Poste

    RCD's in series

    I was having a chat with my electrical boss today about this and that and we discussed wiring a radial in a garden supplying various things like a greenhouse and a garden shed. He was of the opinion that things like greenhouses should be TT'd with an earth spike and RCD protected. The thing is...
  40. G

    RCD tripping on "No Trip" Zs test

    Hi folks, changed a CU over yesterday to a dual RCD board. Standard affair, all tests fine. Did live tests, started doing the Zs for the lights. Both up and downstairs lights kept tripping the RCDs. I'm using my Megger with the 3 leads to avoid tripping. Megger was set to No Trip Loop and all...
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