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Spur off immersion ?

  • 10-04-2009 3:51pm
    #1
    Registered Users, Registered Users 2 Posts: 377 ✭✭


    Hi all,

    Had an electrician out to look at installing a socket for an LCD in the wall.

    Anyway he said the easiest thing would be to do is to take a spur off the immersion as its the other side of partition wall.
    Otherwise it would be ripping up alot of floors and skirting boards etc. to get one off a socket circuit.

    Is this allowed? What are the pros and cons? Should there be any protection put in for the LCD, don't want it blowing up!

    Thanks in advance :)


«1

Comments

  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    It's not allowed.a motorized valve or a pump in the hotpress would be ok.but a socket in another room is a bad idea.


  • Registered Users, Registered Users 2 Posts: 377 ✭✭kodak


    I know its not 100% but why is it so bad?
    Otherwise its going to get very messy..


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    kodak wrote: »
    I know its not 100% but why is it so bad?
    Otherwise its going to get very messy..

    the immersion is a 3kw fixed appliance and has it's own 20amp supply .it's not normally a major hassle to get a socket to a bedroom.is there a supply in the attic.


  • Registered Users, Registered Users 2 Posts: 377 ✭✭kodak


    no other supply in attic or one thats as handy..

    i'm a bit confused regarding the problems an lcd will only be using 200-300 watts.. surley an immersion cable could supply that too?
    or is it totally a different point regardings amps?
    not the best on it all but thanks for all your help


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    it's usually possible to go up to attic and back down to new socket from an existing socket upstairs.i wouldn't even consider the immersion for this as it's not standard practice


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  • Registered Users, Registered Users 2 Posts: 98 ✭✭enmac


    kodak wrote: »
    Hi all,


    Anyway he said the easiest thing would be to do is to take a spur off the immersion as its the other side of partition wall.


    Thanks in advance :)

    yeah, the easiet thing .............
    it's contravening the wiring regulations - get a competent sparks that will do the job in accordance with the regulations


  • Closed Accounts Posts: 56 ✭✭c.a.r.l


    enmac wrote: »
    yeah, the easiet thing .............
    it's contravening the wiring regulations - get a competent sparks that will do the job in accordance with the regulations
    Hi,
    As an Electrical Teacher I would calculate the following:

    The immersion is fed using what we call a radial circuit, This circuit is made up of a 20amp MCB and Rcd, a 2.5mm sq cable.

    You can "spur" off this providing a fused spur is used..let me explain, from the immersion switch/spur a cable is tapped of this and in to feed a "fused connection unit". it is from this fused connection unit that the socket for your lcd is supplied. This is a very simple,straightforward and safe procedure.
    There is no problem in doing this provided the above is adhered to.

    Let me do the maths for you... An immersion heater can use up to 3kw (3000 Watts), I would assume the lcd would not take more than 400watts, so lets say 1000 watts for the lcd (this will never be the case unless its the size of a cinema screen!)

    So using ohms law I (Current) = P (Power) Devided by V (Voltage).....
    so..I = 4000/230 = 17.3 AMPS

    A 2.5mmsq cable is capable of carring 28 amps approx. Realisticly you are not even using half the potential of the cable.

    I hope this helps, but if you need any further advice please email me your number and I will give you a buzz.

    Carl


  • Registered Users, Registered Users 2 Posts: 377 ✭✭kodak


    thanks carl,
    that sounds a good and safe way to do it.
    couple more questions if i may!
    does this fused spur cable need to be 2.5mm sq aswel?
    and can it be tapped into the radial using a 30 amp junction box or would a spur be best?


    thanks for all the help


  • Registered Users, Registered Users 2 Posts: 227 ✭✭paddymick


    kodak wrote: »
    thanks carl,
    that sounds a good and safe way to do it.
    couple more questions if i may!
    does this fused spur cable need to be 2.5mm sq aswel?
    and can it be tapped into the radial using a 30 amp junction box or would a spur be best?


    thanks for all the help

    The cable feeding the spur from the immersion switch would have to be 2.5 but the cable leaving the spur can be smaller depending on the size of the fuse,you should use a 3amp fuse as you will probably be cutting the plug of the flex from the lcd and connecting it straight to the spur,you could also just put a socket on instead of a spur it might be against the regs but if its done right it will be totally safe.

    As for the 30A JB if you can find and tap in to an exsisting socket circuit and done right then that would be your best option


  • Closed Accounts Posts: 56 ✭✭c.a.r.l


    Hi,
    Yes the cable feeding the fused spur from the immersion needs to be a 2.5mm sq. Its quite simple..if the electrician is qualified and competant he will already know this but the fused spur is the same size as a single socket and can be usually and easily mounted flush/surface beside the immersion switch/spur. A small amount of 2.5mmsq cable is just linked across from on to the other and then from the spur to the skt for the lcd.Fuse the spur at approx 3-5amps.

    I wouldn't use a 30A Jb as it is not with the regs.

    The reason you have it on a fused spur and fused with a lower current rating as the Mcb is because if a fault developed with the lcd then the lcd fuse in the new spur would blow first at 3-5 amps!
    If you used say for example a 20 amp fuse or larger in the spur then should a fault develop the fuse will not blow but the fault will travel to the fuse board developing as it travels and blow the mcb in the fuse board protecting the immersion. In some cases the fault will have gathered so much momentium that it blows the main fuse..thus cutting pover to the whole house( this is extreme but does happine)

    I hope this helps but if not just drop me another line.

    Carl


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  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    Don't shoot me here, but I'd probably fit a spur outlet beside the immersion switch and run a 2.5 from there. I'd also be fitting a 5A socket for the TV to avoid someone plugging something else in there.

    The only hazard I can think of, is someone switching off the relevant socket circuit, and assuming the supply is isolated, which they shouldn't be doing anyway.

    How many of us have seen immersion supplies hijacked to feed adjacent sockets, outlets for alarm panels (which shouldn't be in there either) etc.?

    This instance may not be exactly as the regs stipulate, but as a retrofit it's not the worst thing in the world, surely?


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    Don't shoot me here, but I'd probably fit a spur outlet beside the immersion switch and run a 2.5 from there. I'd also be fitting a 5A socket for the TV to avoid someone plugging something else in there.

    The only hazard I can think of, is someone switching off the relevant socket circuit, and assuming the supply is isolated, which they shouldn't be doing anyway.

    How many of us have seen immersion supplies hijacked to feed adjacent sockets, outlets for alarm panels (which shouldn't be in there either) etc.?

    This instance may not be exactly as the regs stipulate, but as a retrofit it's not the worst thing in the world, surely?

    i will.some of the advise here is ridiculous


  • Registered Users, Registered Users 2 Posts: 227 ✭✭paddymick


    First off you cant get a 20A or higher fuse for a 13A plug so blowing the main fuse to the whole house is just stupid and secondly 5A plugs dont usually come with any fuse`s so putting a 5A socket on a 20A circuit is also just stupid,
    The easiest thing to do is just get a good electrician and dont do it yourself because most of the GOOGLE electricians here will just have you running around in circle`s


  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    Hold your horses there chappies.

    Where did I say in my post that a 5A socket was to be backed up by a 20A MCB?

    The words spur and outlet, may offer a clue as to where the 5A fuse goes.

    I'm no fucking Google electrician (whatever the hell that is) either, and I would shoot down any sign of such elitist bullsh1t post haste in my time here. I'm sure Stoner wouldn't be too happy to see such attitude either.

    I place safety and technical knowledge foremost in what I do (which goes way beyond house bashing-with no disrespect to those who make their living therein), and I'd like just one of the hand wringers here to tell me the safety implications in what I am suggesting here.

    A spur outlet from the immersion circuit, fused at 5A, and clearly labelled as such at both ends, both fuse rating and feed (most sparks worth their salt should have a dymo, or other labeller in their arsenal) is unsafe for what reason exactly?

    I assume most people here live in the real world and have seen far worse situations in existing electrical installations, new and old.


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    Hold your horses there chappies.

    Where did I say in my post that a 5A socket was to be backed up by a 20A MCB?

    The words spur and outlet, may offer a clue as to where the 5A fuse goes.

    I'm no fucking Google electrician (whatever the hell that is) either, and I would shoot down any sign of such elitist bullsh1t post haste in my time here. I'm sure Stoner wouldn't be too happy to see such attitude either.

    I place safety and technical knowledge foremost in what I do (which goes way beyond house bashing-with no disrespect to those who make their living therein), and I'd like just one of the hand wringers here to tell me the safety implications in what I am suggesting here.

    A spur outlet from the immersion circuit, fused at 5A, and clearly labelled as such at both ends, both fuse rating and feed (most sparks worth their salt should have a dymo, or other labeller in their arsenal) is unsafe for what reason exactly?

    I assume most people here live in the real world and have seen far worse situations in existing electrical installations, new and old.
    well.my comment was tongue-in-cheek.
    no offence intended.i just think the poster should be advised to fit a13amp socket and connect to a 20a radial socket circuit or direct to fusebox


  • Registered Users, Registered Users 2 Posts: 1,257 ✭✭✭Pete67


    Biggest issue for me would be that the supply to the immersion may not be protected by an RCD, so any socket supply taken from a spur off the immersion supply would similarly not be protected. This greatly increases the risk of electrocution in the event of a fault arising.


  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    I would always have provided RCD protection on immersions and water heaters. Never had an issue, although irons, kettles and the odd fridge have given rise to nuisance trips down through the years.

    I put everything through an RCD these days, what with the forthcoming changes in the regs.

    As I say, I've an open mind on this, I don't do much domestic stuff any more :)


  • Registered Users, Registered Users 2 Posts: 227 ✭✭paddymick


    Pete67 wrote: »
    Biggest issue for me would be that the supply to the immersion would not be protected by an RCD, so any socket supply taken from a spur off the immersion supply would similarly not be protected. This greatly increases the risk of electrocution in the event of a fault arising.

    I know im new here and I shouldnt just jump straight into things but These are the sort of missleading posts im talking about!
    For as long as ive been an electrician the immersion has always gone on the RCD.
    Im also a bit shocked(excuse the pun)at some of the electrical jobs DIY people are asking questions about and thinking that asking advice on a forum is good enough to let them do the work themself.

    @ roundymooney i wasn`t flaming you personally you just have to read some of the post to realise they were writen by people who arn`t electricians and this subject is just too dangerous to get it wrong first time


  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    Agree ++


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    paddymick wrote: »
    I know im new here and I shouldnt just jump straight into things but These are the sort of missleading posts im talking about!
    For as long as ive been an electrician the immersion has always gone on the RCD.
    Im also a bit shocked(excuse the pun)at some of the electrical jobs DIY people are asking questions about and thinking that asking advice on a forum is good enough to let them do the work themself.

    @ roundymooney i wasn`t flaming you personally you just have to read some of the post to realise they were writen by people who arn`t electricians and this subject is just too dangerous to get it wrong first time

    in fairness to pete67 he may be arguing that the immersion circuit may not be protected by an rcd if it's an older installation.which is true.a lot of heated debate stems from posters not reading before they reply (besides the obvious not having a clue what they're talking about)


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  • Registered Users, Registered Users 2 Posts: 227 ✭✭paddymick


    davelerave wrote: »
    in fairness to pete67 he may be arguing that the immersion circuit may not be protected by an rcd if it's an older installation.which is true.a lot of heated debate stems from posters not reading before they reply (besides the obvious not having a clue what they're talking about)

    Well if its an older installation with no RCd then the sockets wont be protected by a RCD either so it makes no differance in that respect.

    I think this tread is heading off in the wrong direction and the main point that should be made is that this is not a DIY job and the original poster needs to get a proper electrician in to do the jod;)


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    paddymick wrote: »
    Well if its an older installation with no RCd then the sockets wont be protected by a RCD either so it makes no differance in that respect.

    I think this tread is heading off in the wrong direction and the main point that should be made is that this is not a DIY job and the original poster needs to get a proper electrician in to do the jod;)

    i'm referring to an older installation with rcd protected sockets and the immersion not-protected .they're commonplace.the requirement for protecting the immersion came in much later. i think this may be what pete67 is referring to.


  • Registered Users, Registered Users 2 Posts: 227 ✭✭paddymick


    davelerave wrote: »
    i'm referring to an older installation with rcd protected sockets and the immersion not-protected .they're commonplace.the requirement for protecting the immersion came in much later. i think this may be what pete67 is referring to.

    OK mate point taken:)


  • Closed Accounts Posts: 1,113 ✭✭✭fishdog


    For as long as ive been an electrician the immersion has always gone on the RCD.
    No for as long as I can remember though. Perhaps I am older than you :D:D There was a time when they were not on the RCD because it was thought they may cause nuisense tripping. Any house wired in the last 20 years should have its immersion on the RCD, but there are still some houses out there with 40 year old wiring :eek::eek:


    I would agree with Carl and Roundymoney on what they have said however:

    As far as I know you are only allowed to spur items related to the water system off the circuit for the immersion element such as motorised valves, pumps etc. Supplying an LCD from it although not a mortal sin is still against the regulations AFAIK.

    Roundymoney:
    I assume most people here live in the real world and have seen far worse situations in existing electrical installations, new and old.

    This is true, but I think it important to be aware that this is against regulations.

    If it has been decided to supply the LCD off the immersion (for whatever reason) why use a socket (13A or 5A) at all?? Why not simply use a spur outlet?? Then there is little or no danger of anyone using it for anything else, other than its intended purpose.

    Furthermore if a spur outlet is used the LCD is a fixed appliance so it is not required to be fed from an RCD.


  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    You're quite right fishdog, in that while it is not a mortal sin, the regs still do not permit it.

    The reason I suggest a socket rather than an outlet is simply for ease of installation, particularly with a short flex mounted high on the wall, and where the socket etc., is hidden behind the unit.

    5A as stated, to avoid Mrs. Murphy plugging a hoover in there.


  • Closed Accounts Posts: 1,113 ✭✭✭fishdog


    RoundyMooney:
    The reason I suggest a socket rather than an outlet is simply for ease of installation, particularly with a short flex mounted high on the wall, and where the socket etc., is hidden behind the unit.
    Fair enough, I know what you mean. I have installed many LCDs and plasmas and all of the ones that I have fitted the power lead can be unplugged from the appliance itself which solves this problem.

    Perhaps this is not the case on all of them.


  • Closed Accounts Posts: 10,910 ✭✭✭✭RoundyMooney


    Hadn't thought of that tbh.


  • Registered Users, Registered Users 2 Posts: 377 ✭✭kodak


    Thanks for all the help.

    The immersion is wired into an rcb.

    The idea of running down from the attic to a socket was not possible due to the stud walls having noggins :mad: and i didn't want any more holes created!

    All is sorted now as the guys boss came out, he was busy before. He said it would be ok but not within regs to do the immersion with a fused spur. Instead he looked in the attic again and fished a new cable into the fuse board downstairs.

    It was a good deal dearer but hey it was done well and neat too and he labelled everything nicely too.

    Now just waiting for LCD to arrive and going to make my own wall bracket. (the shop ones are a bit bulky and expensive too) I presume its ok to hang it from two studs..? Weighs 20KGS

    Thanks for everybody's advice


  • Closed Accounts Posts: 1,113 ✭✭✭fishdog


    I presume its ok to hang it from two studs..? Weighs 20KGS
    If the studs are the standard 4 x 2 and you can get good fixings into 2 of them you should be fine.
    The idea of running down from the attic to a socket was not possible due to the stud walls having noggins and i didn't want any more holes created!
    Sure, but dont forget you will also need to get some sort of signal cables for picture and sound brought to this point such as SCART, HDMI, co axe etc. Getting power there only solves 1/2 of the problem.


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  • Registered Users, Registered Users 2 Posts: 98 ✭✭enmac


    c.a.r.l wrote: »

    I wouldn't use a 30A Jb as it is not with the regs.

    Not too sure about this - but spurring a supply to a TV from the immersion circuit is definitely not allowed in the wiring regulations

    I hope you're not advising your students on such modifications..


  • Closed Accounts Posts: 56 ✭✭c.a.r.l


    Actually enmac, you can spur from a radial one double or one single. I am simply explaining to someone that this practice is not dangerous. Are you telling me that you have never carried out a safe procedure when in a precarious situation?!

    In relation to the 30a Junction box..you have completely taken this out of context! If you read the posts more carefully and stop jumping to write stupit ignorant replies you will see that. If you dont have something educational or less ignorant to add please mind your own business.

    How dare you!!


  • Registered Users, Registered Users 2 Posts: 98 ✭✭enmac


    c.a.r.l wrote: »
    Actually enmac, you can spur from a radial one double or one single. I am simply explaining to someone that this practice is not dangerous. Are you telling me that you have never carried out a safe procedure when in a precarious situation?!

    In relation to the 30a Junction box..you have completely taken this out of context! If you read the posts more carefully and stop jumping to write stupit ignorant replies you will see that. If you dont have something educational or less ignorant to add please mind your own business.

    How dare you!!

    Yes Carl , you can spur from a radial socket circuit - we're talking about the immersion circuit here and it's not permissible to spur a socket off this to feed a TV - If i'm wrong please point out the error

    You're reply to the junction box issue has not provided any further information

    You quoted my contribution in your original post - I am perfectly entitled to a reply - In any case the OP has taken my advice and got a competent sparks to resolve the issue without contravening the wiring rules

    'safe procedure in a precarious situation' - if you eliminate the precarious situation then you won't need a safe procedure - that's what happened inthe end

    Hope you learnt a lesson


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


    A list of the dangers of spuring off the immersion would be interesting, i would`t do it myself, but i dont see the dangers involved either.
    A 5 amp socket definitely would`t be great for sure, as no fuse in the plug itself, but a 13 amp socket off it, wheres the danger in that. The immersion circuit is just like a socket circuit with a 3kw kettle connected,
    so a socket with a tv plugged in does`t seem a big deal, why put a fused spur, if someone plugged in a 2kw heater while the immersion is on where`s the danger,

    Regulations might say no, i dont know that for certain myself, regulations are there as a general safetly measure and change from time to time, and they dont always get tighter, sometimes they relax a little,

    Its better practice to leave immersion to its own circuit alone, but hardly dangerous to connect a socket to it,

    And what about branching off a ring main to a socket in the attic? is that ok, or against regulations, and if you were adding in a socket to the attic, would you wire back to the board in a house with a ring main, Ring mains themselves should be against regs i think


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


    fishdog wrote: »
    No for as long as I can remember though. Perhaps I am older than you :D:D There was a time when they were not on the RCD because it was thought they may cause nuisense tripping. Any house wired in the last 20 years should have its immersion on the RCD, but there are still some houses out there with 40 year old wiring :eek::eek:



    I remember the time no RCD`s were on immersion too, and showers as well.
    The nuisence tripping was indeed a concern, but the RCD is one brilliant device, i dont think anyone who has an understanding of them would feel comfortable even using a shower that does`t have one controlling it.


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    but a 13 amp socket off it, wheres the danger in that.
    Here qre 2 I can think of, I am sure there are more:
    1) If someone turns off every MCB in the board that is marked "socket" this one would still be live.

    2) It is bad practice to ignore the wiring regulations. It can stsrt with a minor infringement and snowball from there.
    The immersion circuit is just like a socket circuit with a 3kw kettle connected
    Except that a kettle can not remain switched on for hours on end.
    why put a fused spur
    This is normal for fixed equipment and it stops someone doing something likeplugging in
    a 2kw heater while the immersion is on
    where`s the danger
    There may be none, but MCBs can fail. It is always better to try to design a circuit so that it is not overloaded.
    Regulations might say no, i dont know that for certain myself
    A TV fed from the immersion is banned I can assure you.
    Its better practice to leave immersion to its own circuit alone
    I agree
    And what about branching off a ring main to a socket in the attic? is that ok, or against regulations
    It is permitted at present, once the entire circuit covers no more than 100m^2
    Ring mains themselves should be against regs i think
    They will be for socket circuits from September next.


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  • Closed Accounts Posts: 3,327 ✭✭✭Merch


    robbie7730 wrote: »
    Regulations might say no, i dont know that for certain myself, regulations are there as a general safetly measure and change from time to time, and they dont always get tighter, sometimes they relax a little,

    Its better practice to leave immersion to its own circuit alone, but hardly dangerous to connect a socket to it,

    And what about branching off a ring main to a socket in the attic? is that ok, or against regulations, and if you were adding in a socket to the attic, would you wire back to the board in a house with a ring main, Ring mains themselves should be against regs i think

    Sorry can you explain this, why would a ring main be against regulations?
    Perhaps I have misread this? but a 2.5mm^2 spur is = to 2.5mm^2 but in a ring circuit it is equal to 5.0mm^2


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


    2011 wrote: »
    Here qre 2 I can think of, I am sure there are more:
    1) If someone turns off every MCB in the board that is marked "socket" this one would still be live.

    relabel

    2) It is bad practice to ignore the wiring regulations. It can stsrt with a minor infringement and snowball from there.

    Spur from ring main is within regs, is it right?? ie 2.5 backed by 32amp mcb


    Except that a kettle can not remain switched on for hours on end.

    and the danger of immersion on for hours is???


    This is normal for fixed equipment and it stops someone doing something likeplugging in

    The danger of plugging something in is???


    There may be none, but MCBs can fail. It is always better to try to design a circuit so that it is not overloaded.


    A TV fed from the immersion is banned I can assure you.




    I agree


    It is permitted at present, once the entire circuit covers no more than 100m^2


    They will be for socket circuits from September next.

    Well i did not say it should be done, just where are the dangers, i agree with not doing it, but cant i ask what peoples opinions on the dangers are

    Immersion mcb can be relabeled, would you work on a socket according to switching off by its label

    immersion left on hours on end,,,, wheres the danger?

    The regulations? I agree, keep within regs for sure
    But its within regs to branch off to a single socket from a ring main you say, so you have a 2.5 cable backed by a 32amp mcb, hardly great, and surely worse than connecting a socket to a 20amp protected circuit

    And using spur, no problem using that but whats problem using socket, what danger is there from someone plugging in, spurs are used for fixed appliances as you said, but with an RCD on immersion then a socket would be hardly a danger.

    Tv fed from immersion, well its not connected to the immersion element.

    Anyway, its just a matter of interest question, not a recommendation to use immersion circuit as a socket circuit, so keep that in mind


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


    Merch wrote: »
    Sorry can you explain this, why would a ring main be against regulations?
    Perhaps I have misread this? but a 2.5mm^2 spur is = to 2.5mm^2 but in a ring circuit it is equal to 5.0mm^2


    Well my thought on ring mains is why use them, you have a 32 amp mcb with 13 amp sockets, also if a loose connection occurs in a socket, it will not show up, unless it happens in 2 places, but now you have in effect 2 radials of 2.5 wiring but still backed by a 32amp breaker. Radials do the job grand i would of thought, and they show up any faults which ring mains may not,

    Also if you spur off it the spur circuit now has 2.5 cable backed by 32 amp protection,

    Again im just wondering what others think


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    Immersion mcb can be relabeled
    True
    would you work on a socket according to switching off by its label
    No, but the point is some people would.
    immersion left on hours on end,,,, wheres the danger?
    I was highlighting the difference between athe kettle and the immersion.

    Sorry Robbie I will reply to the rest of your post later, I have to run!


  • Registered Users, Registered Users 2 Posts: 1,007 ✭✭✭stevoslice


    I put everything through an RCD these days, what with the forthcoming changes in the regs. :)

    What are these changes you speak of?


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


    c.a.r.l wrote: »
    Hi,
    As an Electrical Teacher I would calculate the following:

    The immersion is fed using what we call a radial circuit, This circuit is made up of a 20amp MCB and Rcd, a 2.5mm sq cable.

    You can "spur" off this providing a fused spur is used..let me explain, from the immersion switch/spur a cable is tapped of this and in to feed a "fused connection unit". it is from this fused connection unit that the socket for your lcd is supplied. This is a very simple,straightforward and safe procedure.
    There is no problem in doing this provided the above is adhered to.

    Let me do the maths for you... An immersion heater can use up to 3kw (3000 Watts), I would assume the lcd would not take more than 400watts, so lets say 1000 watts for the lcd (this will never be the case unless its the size of a cinema screen!)

    So using ohms law I (Current) = P (Power) Devided by V (Voltage).....
    so..I = 4000/230 = 17.3 AMPS

    A 2.5mmsq cable is capable of carring 28 amps approx. Realisticly you are not even using half the potential of the cable.

    I hope this helps, but if you need any further advice please email me your number and I will give you a buzz.

    Carl

    I think any electrician on this forum can calculate that, and while i have said i dont really see any dangers of spuring off the immersion, its best and proper practice not to, it keeps the electrical installation clean and simple.

    For instance it would`t really be any more dangerous to spur from the shower isolator or pull chord using a fused spur close to the shower isolator than it would from immersion circuit. But i would`t like to think anyone would do that.

    As your calculations show, the immersion circuit would`t be overloaded during normal use, and is electrically sound. Its just proper practice to keep the immersion for its own use on the circuit, or as others said maybe
    power water valves or a pump within the hot press from it.


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    But its within regs to branch off to a single socket from a ring main you say, so you have a 2.5 cable backed by a 32amp mcb, hardly great, and surely worse than connecting a socket to a 20amp protected circuit
    You make a fair point here. I do agree with you that it does not nake much sense to spur off a ring circuit, but my point is that according to current regulations you are permitted to do this.

    Well my thought on ring mains is why use them, you have a 32 amp mcb with 13 amp sockets, also if a loose connection occurs in a socket, it will not show up, unless it happens in 2 places, but now you have in effect 2 radials of 2.5 wiring but still backed by a 32amp breaker. Radials do the job grand i would of thought, and they show up any faults which ring mains may not,

    Also if you spur off it the spur circuit now has 2.5 cable backed by 32 amp protection,

    Again im just wondering what others think
    I agree with you here completly.
    In addition:
    Accroding to the regulations you can have an unlimited nu,ber of sockets fed from a ring circuit once it is within 100m^2. Therfore in theory a single circuit could have 1000 sockets on it!!! That is crazy.


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


    2011 wrote: »
    You make a fair point here. I do agree with you that it does not nake much sense to spur off a ring circuit, but my point is that according to current regulations you are permitted to do this.



    I agree with you here completly.
    In addition:
    Accroding to the regulations you can have an unlimited nu,ber of sockets fed from a ring circuit once it is within 100m^2. Therfore in theory a single circuit could have 1000 sockets on it!!! That is crazy.


    yes ive said for a long time ring mains are not good, i never liked them since apprentice days,
    My whole point about regs is they are not perfect, but its good practice to keep within them, no competent person will argue with that,

    But when anyone says something is wrong because its outside the regs, or something is correct because the regs say it is, is it absolutely gospel?


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    But when anyone says something is wrong because its outside the regs, or something is correct because the regs say it is, is it absolutely gospel?
    IMHO when an installation is certified the cert itself is a legal document. If you ignore/break the regulations and sign off on it you could be in hot water.

    I do agree that it is possible to do a job that complies with the regulations but is still done to a poor standard. The ring socket circuit is an example of that.


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


    2011 wrote: »
    IMHO when an installation is certified the cert itself is a legal document. If you ignore/break the regulations and sign off on it you could be in hot water.

    I do agree that it is possible to do a job that complies with the regulations but is still done to a poor standard. The ring socket circuit is an example of that.

    yes agreed


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    robbie7730 wrote: »
    Well my thought on ring mains is why use them, you have a 32 amp mcb with 13 amp sockets, also if a loose connection occurs in a socket, it will not show up, unless it happens in 2 places, but now you have in effect 2 radials of 2.5 wiring but still backed by a 32amp breaker. Radials do the job grand i would of thought, and they show up any faults which ring mains may not,

    Also if you spur off it the spur circuit now has 2.5 cable backed by 32 amp protection,

    Again im just wondering what others think

    advantages for rings:increased csa/capacity.reduced voltage drop for longer runs.i would do spurs normally in 3*4 so not an issue really.
    other misc. advantages :ring can be split in case of damage or fault,also earth continuity is mainatained in a single break
    the major issue obviously is an undetected break in L or N reducing the capacity of the circuit


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    Personally I think the disadvantages outweigh the advantages. Either way they will be banned soon.

    also earth continuity is mainatained in a single break
    .....but the earth fault loop impedence may then be too high for a 32A MCB.


  • Closed Accounts Posts: 1,712 ✭✭✭davelerave


    true


  • Registered Users, Registered Users 2 Posts: 534 ✭✭✭PaulieBoy


    If you where to spur of the Immersion to feed an outlet and then got a RECCI guy out to cert the house, would he pass it ???


  • Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    If you where to spur of the Immersion to feed an outlet and then got a RECCI guy out to cert the house, would he pass it ???
    If the spur was used to feed something located in the hot press like a shower pump then you would be ok. For a TV, no he would not cert it.


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