Getting power from one source to 2 wall sockets

EpiphoneSpecial

Hi All,

I have a bedroom with one set of cables coming into it.

I want to install 2 new wall sockets in the room.
Is a Terminal Junction Box the best way to split the power?
Like This One?

I'm guessing the function of this box is to take one source in and send 2 sources out?

Cheers

b318isp

You will have to loop them. See this picture:



AFAIK you can spur only one socket off a domestic ring main, but to get two you must loop.

EpiphoneSpecial

1. connect power source to junction box "in"
2. connect junction box to socket1
3. coonect socket1 and socket2 (plug 2 lives, 2 neutrals into each terminal?)
4. connect socket2 back into junction box

i'm a close?

brightspark

b318isp wrote: »

You will have to loop them. See this picture:



AFAIK you can spur only one socket off a domestic ring main, but to get two you must loop.

What makes you think he has a ring circuit?

Any spurs MUST be protected by an over current device (non-fused spurs are no longer allowed)

You used to be allowed the same number of spurs as outlets on a ring, the requirement to put in a fused spur outlet now means that it isn't really cost effective not to include most sockets within the ring.

brightspark

EpiphoneSpecial wrote: »

1. connect power source to junction box "in"
2. connect junction box to socket1
3. coonect socket1 and socket2 (plug 2 lives, 2 neutrals into each terminal?)
4. connect socket2 back into junction box

i'm a close?

Not sure you should be taking on this job. The junction box you linked to would be bad practice.

(Adding one outlet would be considered "minor works", but adding more is strictly speaking "controlled works")

2011

brightspark wrote: »

Not sure you should be taking on this job. The junction box you linked to would be bad practice.

(Adding one outlet would be considered "minor works", but adding more is strictly speaking "controlled works")

Agree on both counts.

Bruthal

brightspark wrote: »

Not sure you should be taking on this job. The junction box you linked to would be bad practice.

(Adding one outlet would be considered "minor works", but adding more is strictly speaking "controlled works")

Yea the worst junction boxes ever invented them yokes

Sir Arthur Daley

Bruthal wrote: »

Yea the worst junction boxes ever invented them yokes

+ 1 but the old school electricians might have different view on them

2011

Anyway, to assist you with your question.....

EpiphoneSpecial wrote: »

Hi All,

I have a bedroom with one set of cables coming into it.

By one set of cables do you mean two cables?

Generally sockets in a domestic installation are wired in 2.5mm sq. win & earth cable as shown in the picture below. Can you confirm that your cable is like this?

I want to install 2 new wall sockets in the room.
Is a Terminal Junction Box the best way to split the power?

No, although junction boxes are permitted it is generally considered bad practice to use one for a socket circuit.

Ideally the only joins on a socket circuit cable are at the sockets themselves.
Most electricians nowadays would say that is best to wire radial socket circuits such as this:



I am not a fan of ring socket circuits.

I'm guessing the function of this box is to take one source in and send 2 sources out?

It can be. But connecting 3 cables together in a single junction box can often be difficult as the terminals often only have enough space for two cables.

A few things to note:

1) A radial socket circuit should supply no more than 10 double socket outlets. You need to ensure that the addition of sockets will not push this circuit beyond this.

2) Typically a socket circuit in a domestic installation is supplied by a 20A B type MCB (but not always). You should identify what type MCB is protecting this circuit.

3) Socket circuits should also have supplementary protection from an RCD. Something this is achieved by installing an RCBO. You should ensure that your socket circuits are protected this way.

4) All connections should be throughly tightened.

5) The earth conductor should be sleeved with PVC green/yellow sleeving.

6) All additions to the installation should be properly tested as per the ETCI regulations.


I am hoping that this gives you a better insight.
My advice to you is to get a qualified electrician to do this work, preferably a registered electrical contractor.

Remember mains voltage can be lethal!

zega

Why do you reckon radial's are better than ring circuits?

brightspark

zega wrote: »

Why do you reckon radial's are better than ring circuits?

The problem with a ring circuit is it is if any point in the circuit breaks you effectively have a 2.5mm cable 'protected' by the 32A MCB :eek:
And there will be no indication of a break, i.e. all sockets work normally, if you had a break in a radial circuit the sockets beyond the fault won't work.

Sir Arthur Daley

brightspark wrote: »

The problem with a ring circuit is it is if any point in the circuit breaks you effectively have a 2.5mm cable 'protected' by the 32A MCB :eek:
And there will be no indication of a break, i.e. all sockets work normally, if you had a break in a radial circuit the sockets beyond the fault won't work.

Any time i used ring circuits i protected them via a 20 amp mcb.

zega

brightspark wrote: »

The problem with a ring circuit is it is if any point in the circuit breaks you effectively have a 2.5mm cable 'protected' by the 32A MCB :eek:
And there will be no indication of a break, i.e. all sockets work normally, if you had a break in a radial circuit the sockets beyond the fault won't work.

Ah yeah fair enough.instructor in phase 2 said that radials were more popular now but never really went into why

thanks

2011

WikiHow wrote: »

Any time i used ring circuits i protected them via a 20 amp mcb.

Why?
This means that you have effectively lost the advantages if having a ring circuit.


This is also against the regulations (ET101:2008).
Have a look at Annex 55A section 5.
This is for "Ring Final Circuits in Domestic & Similar Installations".
Under this heading in section 5.1 it states that socket circuits wired in a ring must be protected by a "Fuse/MCB rating: 35A/32A".

Bruthal

zega wrote: »

Ah yeah fair enough.instructor in phase 2 said that radials were more popular now but never really went into why

thanks

Not a fan of them myself either in domestic setups.

Other problems include the ends of the ring being connected to different MCBs by mistake. A serious blunder but it does happen, although this is more a fault of the person rather than the ring itself.

Or the earth being broken somewhere, so 32 amp circuit with 1.5 or maybe even 1 square earth, although with the RCD, it should still be ok, but not great. A similar problem can happen to radial circuits too anyway.

Bruthal

2011 wrote: »

Why?
This means that you have effectively lost the advantages if having a ring circuit.

Some advantages might still exist such as better loop impedance on longer circuits.

frankmul

2011 wrote: »

Why?
This means that you have effectively lost the advantages if having a ring circuit.


This is also against the regulations (ET101:2008).
Have a look at Annex 55A section 5.
This is for "Ring Final Circuits in Domestic & Similar Installations".
Under this heading in section 5.1 it states that socket circuits wired in a ring must be protected by a "Fuse/MCB rating: 35A/32A".

That 32amp would just be a recommendation. The max size allowed. Anything small would be safer but prone to nuisance tripping.

tomdempsey200

is it a rule or a recommendation?

i was told to change them from 20 to 32 on a reci inspection a few years back

EpiphoneSpecial

Thanks for all info. Didn't get a chance to do any work in house over weekend. Will post pics during week when I'm painting room.

2011

frankmul wrote: »

That 32amp would just be a recommendation. The max size allowed. Anything small would be safer but prone to nuisance tripping.

Where does it say that this is a recommendation?
I took a direct quotation from the ET101:2008

I was told that this was a regulation.
When I checked the regulations it confirmed what I was told.
That is the whole point of a ring circuit, a larger protective device can be installed.
Otherwise why bother?

Bruthal

2011 wrote: »

Where does it say that this is a recommendation?
I took a direct quotation from the ET101:2008

I was told that this was a regulation.


Otherwise why bother?

Bit strange that downgrading an MCB would be against regs. Where`s the danger?

2011

Bruthal wrote: »

Bit strange that downgrading an MCB would be against regs. Where`s the danger?

Nuisance tripping is more likely with say a 20A MCB. Remember a ring socket circuit typically has far more sockets on it than a radial.

My guess:
Nuisance tripping of RCDs and MCBs frequently leads to guntering such as bypassing the device altogether. Kind of like the old wrap the fuse in tinfoil trick.

brightspark

2011 wrote: »

Where does it say that this is a recommendation?
I took a direct quotation from the ET101:2008

I was told that this was a regulation.
When I checked the regulations it confirmed what I was told.
That is the whole point of a ring circuit, a larger protective device can be installed.
Otherwise why bother?

I agree why bother with a ring if you are only going to use a 20A MCB.

However, Annex 55A is listed as "Informative" meaning it's not mandatory but contains useful information that is necessary for an understanding of the Rules.

Tuco88

I recently replaced a pump in a house, and I noticed that all the MCBs were of the C type, I tested the impedance all fine (Sockets only) and noted it to my employer. Id sleep better if they were B types for the tripping current 3-5. My question is are these fine or allowed?

Id find ring circuits very practical in kitchens, They can supply a great area, reduce overload tripping, better impedance value. Reduce the amount of MCBs in the board. If the cable does break/cut the what are the odds of it not tripping? I agree worst case if it cant be repairs 2 circuits possible greater than 10 sockets on each... Granted I don't wire too many houses so maybe there not practical give the risks.

Regards OP if the joint is in the attic/crawl space might be handy to just place a double socket there if practical, Acts as a joint and my come in handy.

tomdempsey200

Tuco88 wrote: »

I recently replaced a pump in a house, and I noticed that all the MCBs were of the C type, I tested the impedance all fine (Sockets only) and noted it to my employer. Id sleep better if they were B types for the tripping current 3-5. My question is are these fine or allowed?

Id find ring circuits very practical in kitchens, They can supply a great area, reduce overload tripping, better impedance value. Reduce the amount of MCBs in the board. If the cable does break/cut the what are the odds of it not tripping? I agree worst case if it cant be repairs 2 circuits possible greater than 10 sockets on each... Granted I don't wire too many houses so maybe there not practical give the risks.

Regards OP if the joint is in the attic/crawl space might be handy to just place a double socket there if practical, Acts as a joint and my come in handy.

in the section on overcurrent protective devices it seems to state that type B 'must be used' unless there's need for C or D

if i'm reading it correctly

brightspark

Tuco88 wrote: »

I recently replaced a pump in a house, and I noticed that all the MCBs were of the C type, I tested the impedance all fine (Sockets only) and noted it to my employer. Id sleep better if they were B types for the tripping current 3-5. My question is are these fine or allowed?

Regulation 533.3.4

MCBs and RBBOs shall be selected so as to be suitable for the duty intended.
For final circuits MCBs and RCBOs shall have Type B characteristics.

For circuits where high inrush currents of the order 5-10 In May occur shall have type C.

In other words only if you expect high inrush currents should you use other than type B.

Tuco88 wrote: »

Id find ring circuits very practical in kitchens, They can supply a great area, reduce overload tripping, better impedance value. Reduce the amount of MCBs in the board. If the cable does break/cut the what are the odds of it not tripping? I agree worst case if it cant be repairs 2 circuits possible greater than 10 sockets on each... Granted I don't wire too many houses so maybe there not practical give the risks.

Annex 55A 5.1 says that ring circuits should not be used in kitchens, but you could argue that the Annex is only informative and therefore not mandatory but recommended?

Worst case is two circuits more than 10 outlets each, supplied with 2.5sq which isn't protected by a 32A MCB!

2011

brightspark wrote: »

In other words only if you expect high inrush currents should you use other than type B.

+1

but you could argue that the Annex is only informative and therefore not mandatory but recommended?

Under Annex 55A it the wording used is "normative", not "informative".
Either way at the very least it should be read as a recommendation.
In my view recommendations should only be ignored if there is a very good reason for doing so.

Worst case is two circuits more than 10 outlets each, supplied with 2.5sq which isn't protected by a 32A MCB!

Or someone takes the p!ss and installs a ridiculous number of sockets on a single circuit as I hav eseen done.

2011

Tuco88 wrote: »

Id find ring circuits very practical in kitchens

As already stated this is not permitted.

They can supply a great area

So can radial circuits.
I have seen very large rooms, homes, offices and large plants served with radial socket circuits without any issue.

reduce overload tripping

In my opinion if 20A socket circuits are tripping that is down to bad design or installation issues.

better impedance value

If you desire a lower impedance valve my advice is to use a larger cable.
Sockets such as MK logic plus can be used to terminate 4sq. mm cables without any issue.

Reduce the amount of MCBs in the board

Yes it may be possible to have less MCBs by installing ring socket circuits.
However I would rather have more MCBs.
That way the loss of a circuit will have a reduced impact on the overall installation.

If the cable does break/cut the what are the odds of it not tripping?

Quite low.
Generally the errors are made during installation and are not picked up due to little or no testing taking place.
I have seen two ring circuits "crossed" so that they are fed from two MCBs :eek:

Regards OP if the joint is in the attic/crawl space might be handy to just place a double socket there if practical, Acts as a joint and my come in handy.

Agreed

Tuco88

Annex 55A 5.1 says that ring circuits should not be used in kitchens, but you could argue that the Annex is only informative and therefore not mandatory but recommended?

Worst case is two circuits more than 10 outlets each, supplied with 2.5sq which isn't protected by a 32A MCB![/QUOTE]

Thanks for the info, This forum is very handy top lads here. I was worried about that myself, I just wanted to know how did it pass RECI inspection? the house is 7 years old at best. I didn't believe you there for a sec on the ring not being allowed in the kitchen, I never noticed that change from the Third edition noted now, last ring I put in was back in Fas . Sorry I was looking from the previous comment on the 20 Amp, Radial all the way I guess Just to note in the case stated, 32 amp over the 2.5mm² I agree its poor, But a 2.5mm² will take much greater current than 32Amps before it starts to break down, I know not relevant but from a tested point.

The one thing I very much dislike about the Regs is the grey areas in it, for example 63amp MCB covering the Tails to the consumer unit is not needed if the tails are less than 3m unless it has changed? Same with the Bathroom light on an RCD depending which zone it is. Things can be made very easy like all bathroom lights on an RCD/all tails on a 63A MCB etc...

2011

Tuco88 wrote: »

I was worried about that myself, I just wanted to know how did it pass RECI inspection?

These inspections are very hit and miss in my opinion.
A search here will confirm that.
Perhaps the threat of a inspection from CER will change the attitude of some of the RECI inspectors.

But a 2.5mm² will take much greater current than 32Amps before it starts to break down

Yes, you are correct, but only under test conditions.
We try to ensure through good design that a 2.5 would never be carrying 32A.
If you were to look at the fusing curve for a 32A B Type MCB you would see that it would operate at 36A without tripping indefenitley.
I would be quite confident that 36A going through a 2.5mm sq. cable for hours on end would cause serious damage to the cable.

brightspark

2011 wrote: »

+1


Under Annex 55A it the wording used is "normative", not "informative".
Either way at the very least it should be read as a recommendation.
In my view recommendations should only be ignored if there is a very good reason for doing so.

Not in my print (2013?) it's definitely "informative", which print version are you using?

But as you said, you would want to have a good reason for ignoring it.

EDIT... It's in the errata

http://www.etci.ie/docs/et101a12011.pdf

(The 2013 print is supposed to have the Ammendment Incorporated!)

Annex 55A, Title: Delete “Normative”, insert “Informative”.