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consumer unit regs

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  • 02-01-2011 3:08pm
    #1
    indie armada
    Registered Users Posts: 834 ✭✭✭


    looking for some info with respect to consumer units and how they should be wired. i have a mate who is having problems with nuisence tripping on his rcd(sockets)
    it turns out that when this happens, he looses power to his heating and his showers and possibly his immersion, allthough hes yet to confirm this.
    im under the impression that only sockets should be wired into the rcd, but is it ok to have the heating on a spur off the socket circut and from what hes told me the shower is a mixer type fed from the hwc but have a pull cord for isolating. is it ok to have these type of showers fed off the socket circut?
    his neighbour is having similar problems and it seems to me that the board supplied to the sparks, in this case garo, which come assembled didnt have enough mcbs for what the installation needed and the sparks just doubled up on the mcbs instead retro fitting the ammount that is needed.
    as far as the tripping is concerned , and on the basis of what hes told me i think its the fridge, could it be when the motor kicks in its causing the tripping, and if so would it be a good idea to fit a c curve rcd to rectify this?


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    #2
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    Put the shower and immersion on their own rcbo's. This will avoid problems in the future, even if it's not the problem now...

    What is actually tripping? An mcb or the rcd?


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    #3
    sparcocars
    Registered Users Posts: 148 ✭✭sparcocars


    indie armada wrote: »
    looking for some info with respect to consumer units and how they should be wired. i have a mate who is having problems with nuisence tripping on his rcd(sockets)
    it turns out that when this happens, he looses power to his heating and his showers and possibly his immersion, allthough hes yet to confirm this.
    im under the impression that only sockets should be wired into the rcd, but is it ok to have the heating on a spur off the socket circut and from what hes told me the shower is a mixer type fed from the hwc but have a pull cord for isolating. is it ok to have these type of showers fed off the socket circut?
    his neighbour is having similar problems and it seems to me that the board supplied to the sparks, in this case garo, which come assembled didnt have enough mcbs for what the installation needed and the sparks just doubled up on the mcbs instead retro fitting the ammount that is needed.
    as far as the tripping is concerned , and on the basis of what hes told me i think its the fridge, could it be when the motor kicks in its causing the tripping, and if so would it be a good idea to fit a c curve rcd to rectify this?

    The sockets, immersion and the heating should be going through a 63 amp rcd alright and then the respective circuits are brought through their own mcb. The shower should be on its own rcd and mcb or a rcbo if its an electric instant shower but if its just a power shower then sharing the other rcd and having its own mcb would do although its not the way i would do it anyway. C curve is to bo with MCB's and not rcd's. All an rcd does is sense earth leakage by means of two coils inside it, one for live and one for neutral. Under normal circumstance the current will be the same in each coil and their magnetic flux density cancels eachother out but if there is leakage to earth from live or neutral then the density changes and it trips. Isolate all circuits off rcd by turning off each mcb and plug everything out of the sockets. Turn each mcb on one at a time until the rcd trips. If it trips you know where the problem is and if it doesn't trip then it could be something that was plugged in. Plug each item back in to their sockets one at a time until it trips and you should find the problem then.


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    #4
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    ya-domestic pumps require 30mA protection-boilers are usually spurred anyhow


    but as already said you can rcbo some of these circuits to prevent the nuisance with shared rcd's

    and instantaneous showers is separate rcd/rcbo -rules


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    #5
    indie armada
    Registered Users Posts: 834 ✭✭✭indie armada


    DublinDilbert wrote: »
    Put the shower and immersion on their own rcbo's. This will avoid problems in the future, even if it's not the problem now...

    What is actually tripping? An mcb or the rcd?

    the rcd is tripping......


    @ sparcocars.......it is tripping intermittantly, so the method of isolating everthing then switching one by one doesnt work in this instance.
    this is going on a while now and i originally suggested to him to replace the rcd and/or isolate the kitchen sockets and put them on their own rcd to help identify which circut is causing it.
    over the xmas while he was away, with everything unplugged and heating off it tripped, which is why i think its the fridge cause it was the only thing on. i will be getting one of the many sparks i know to look at this but i want to get a head start so it takes as little time /money as possible.
    thanks for the replys.


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    #6
    indie armada
    Registered Users Posts: 834 ✭✭✭indie armada


    M cebee wrote: »
    ya-domestic pumps require 30mA protection-boilers are usually spurred anyhow


    but as already said you can rcbo some of these circuits to prevent the nuisance with shared rcd's

    and instantaneous showers is separate rcd/rcbo -rules

    so in theory if i open up a pre wired board, from the 63a neozed switch fuse i see a live tail to the bottom of the rcd and a second to the busbar for the lighting mcbs.
    i then have a live tail out of the top of the rcd to the first mcb for the sockets which is commoned with the other sockets via a busbar.
    i should also have a neutral to the rcd and a tail from the top of the rcd to the neutral bar for the sockets and a separate tail to the second busbar for the lighting.
    now for domestic pumps,heating, cooker ect, where do you obtain the live, do you simply extend the lighting busbar and fit your respective rcbos/mcbs fed from it or do you extend the busbar feeding the sockets and take your supply from there. or are they fed from the outgoing side of the neozed.


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    #7
    DublinDilbert
    Registered Users Posts: 5,379 ✭✭✭DublinDilbert


    It sounds like there's far to much on the rcd to narrow down the problem. Also throw in the fact that it might be a wiring problem, eg damaged insulation. You might find it by trial and error, but it will be a real pain.

    There would typically be a bus bar connecting live to all the mcbs that aren't on the rcd, eg lights, cooker, heating.


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    #8
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    -you can IR test fixed wiring

    -afaik to check for faults you can
    link L-N on load side of rcd
    IR test at 250v to earth with appliances in situ
    with rcd off and supply disconnected

    -you can measure leakage current ,ramp test rcd

    -or rcbo suspect circuits


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    #9
    indie armada
    Registered Users Posts: 834 ✭✭✭indie armada


    DublinDilbert wrote: »
    It sounds like there's far to much on the rcd to narrow down the problem. Also throw in the fact that it might be a wiring problem, eg damaged insulation. You might find it by trial and error, but it will be a real pain.

    There would typically be a bus bar connecting live to all the mcbs that aren't on the rcd, eg lights, cooker, heating.


    thats what i thought, so if you have to fit an rcbo for neg head pump for instance, it would be fed from the live for the lights, cooker ect and not from the busbar feeding the sockets.

    ps...these questions are with ref to a 2 row board in a domestic instalation.

    thanks for the replys.


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    #10
    indie armada
    Registered Users Posts: 834 ✭✭✭indie armada


    M cebee wrote: »
    -you can IR test fixed wiring

    -afaik to check for faults you can
    link L-N on load side of rcd
    IR test at 250v to earth with appliances in situ
    with rcd off and supply disconnected

    -you can measure leakage current ,ramp test rcd

    -or rcbo suspect circuits

    as far a testing goes the most i will do is with a socket tester, anything after that is out of my dept and abillity. :o


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    #11
    M cebee
    Closed Accounts Posts: 4,431 ✭✭✭M cebee


    ya- i meant these are some ideas for nuisance problems
    do ye sell many single mod rcbo's out of interest


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    #12
    indie armada
    Registered Users Posts: 834 ✭✭✭indie armada


    M cebee wrote: »
    ya- i meant these are some ideas for nuisance problems
    do ye sell many single mod rcbo's out of interest

    no, ive seen them comming in for specific customers but we only keep the normal hager/abb type on the shelf.


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    #13
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Seperate the immersion onto an RCBO on its own if possible, and the shower even though its just a power shower. This could stop the nuisance tripping anyway, as a lot of items on the one RCD can add up the small amounts of leakage there will be on water appliances anyway. And would help identify what item is the problem too possibly.


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