Spur off immersion ?

kodak

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

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.

kodak

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

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.

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

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

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

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

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

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

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

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?

davelerave

RoundyMooney wrote: »

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

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

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.

davelerave

RoundyMooney wrote: »

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

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.

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

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

RoundyMooney

Agree ++

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)

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;)

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.

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:)

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 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.

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.

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.

RoundyMooney

Hadn't thought of that tbh.

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

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.

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..