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Discuss how many cables can you fit in to a circuit breaker in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

M

marty1234

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anyone know the reg on how mainy cable can go into a circut breaker .
i know on a ring there will be 2 , shower ther will be 1,cooker 1, what about lighting circuits . I was doing some work in a shop and some other spark is fitting new emg lights he is wiring them out off the lighting 6 amp circuit that has 2 1.5 cables in it at present so he is making it 3 .I would wire from the light switch and fit a test key so i did not have 3 cables in the one breaker
some help on this thanks
 
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S

Spudnik

  • Thread Starter Thread Starter
  • #2
As long as its not ALL the lighting on one breaker then i can see no prob.

Common sense would tell you to make sure they are all secure.

Personally i would probably limit to 3 or 4 at a push.
 
anyone know the reg on how mainy cable can go into a circut breaker .
i know on a ring there will be 2 , shower ther will be 1,coocker 1, what about lighting circuits . I was doing some work in a shop and some other spark is fitting new emg lights he is wiring them out off the lighting 6 amp circuit that has 2 1.5 cables in it at present so he is making it 3 .I would wire from the light switch and fit a test key so i did not have 3 cables in the one breaker
some help on this thanks
I would do the same as you.I don't know if there is a particular reg prohibiting it,but to me,a lighting circuit should only have ONE cable at the circuit breaker.If there are more,then surely they should be on a separate circuit with their own CB. I believe that this way you can properly test a circuit,and record results.How do you record results if you have numerous
circuits coming from one CB?
 
M

marty1234

  • Thread Starter Thread Starter
  • #4
thanks mrloy99 you think the same way as me mate . I think 1 cable to each CB for testing the job i would likr to find some sort off reg for this but dont see one . The sparks that are doneing the job seem to think thay are right putting 3 and 4 cables in 1 breaker for there emg lights .Also they are doing fire alarms in the same job so i had i look 5 cables out 1 10 amp breaker 1 for there new fire alarm,2 intruder alarm ,3 central heating,4 roller shutter,5 socket in back shop
I think these guy have to have a think in what they are doing . STILL TO SEE TEST SHEET ON ALL THE 31 JOBS I HAVE LOOKED AT
 
M

maddfridge

  • Thread Starter Thread Starter
  • #5
anyone know the reg on how mainy cable can go into a circut breaker .
i know on a ring there will be 2 , shower ther will be 1,coocker 1, what about lighting circuits . I was doing some work in a shop and some other spark is fitting new emg lights he is wiring them out off the lighting 6 amp circuit that has 2 1.5 cables in it at present so he is making it 3 .I would wire from the light switch and fit a test key so i did not have 3 cables in the one breaker
some help on this thanks
hi there

section314

regulation 314.2 is what you are looking for as separate circuits and control, isolation etc

1 breaker 1 circuit as far as i can see end of problem above states that to me

cheers
:)
 
thanks mrloy99 you think the same way as me mate . I think 1 cable to each CB for testing the job i would likr to find some sort off reg for this but dont see one . The sparks that are doneing the job seem to think thay are right putting 3 and 4 cables in 1 breaker for there emg lights .Also they are doing fire alarms in the same job so i had i look 5 cables out 1 10 amp breaker 1 for there new fire alarm,2 intruder alarm ,3 central heating,4 roller shutter,5 socket in back shop
I think these guy have to have a think in what they are doing . STILL TO SEE TEST SHEET ON ALL THE 31 JOBS I HAVE LOOKED AT
that is just crazy s*it.Must be contravening a load of regs there.I know fire alarms HAVE to be on their own.I would imagine,the intruder alarm stuff should be on their own too.Totally separate circuits they all should be on individual mcbs.The 10amp mcb on the sockets is a mite unusual too.Even trying to locate a fault on such a multicircuit must be a nightmare.Have they got rcds on sockets and stuff buried in walls at less than 50mm?
 

Des 56

-
Arms
Esteemed
Why do you think that more than 1 cable in a breaker is poor practise
If the lighting circuit was both sides of a dist board routing wise then it is safer to feed both sides from the dist board reducing the zs compared with long runs
This is one practical example
There is nothing whatsoever wrong with multiple feeds at one breaker
Circuit design does not have to be as demonstrated in the guides
Safety is the criteria not unusual layouts
 
N

ninjadeathstalk

  • Thread Starter Thread Starter
  • #8
anyone know the reg on how mainy cable can go into a circut breaker .
i know on a ring there will be 2 , shower ther will be 1,coocker 1, what about lighting circuits . I was doing some work in a shop and some other spark is fitting new emg lights he is wiring them out off the lighting 6 amp circuit that has 2 1.5 cables in it at present so he is making it 3 .I would wire from the light switch and fit a test key so i did not have 3 cables in the one breaker
some help on this thanks
I agree with you on the cooker and shower circuits only one per circuit, but don't forget that a ring main can have more than 2, if a spur is taken off from the consumer unit there would be 3 cables to the mcb.

With the emergency lighting this would need to be taken from the same supply as the lighting for that area, or else it would not illuminate when the supply goes down.

I wouldn't take the supply from the switch. I would take the supply from the nearest light fitting because otherwise you wouldn't have a neutral for the emergency lights.

The total circuit current would need to be calculated and if necessary a new circuit would need to be installed. Because the emergency lighting wouldn't draw very much power, it may well be possible to put them all on the same supply.
 
M

matt20687

  • Thread Starter Thread Starter
  • #9
the new regs state that only one wire is aloud in each mcb. Although it is stupid that as long as you join the cable outside of the CU then it is fine to have multiple circuits!
 

DPG

-
Arms
Esteemed
Patron
Where in new regs does it say only 1 cable in each MCB? Are you saying we now can't have a spur fed from the ring circuit mcb?
 
S

slrichardson

  • Thread Starter Thread Starter
  • #11
Came across this on a pir. Had 2 lighting circuits on one 6a mcb. Checked with niceic for their views and was told its a code 4 'does not comply with bs7671'
 
Why do you think that more than 1 cable in a breaker is poor practise
If the lighting circuit was both sides of a dist board routing wise then it is safer to feed both sides from the dist board reducing the zs compared with long runs
This is one practical example
There is nothing whatsoever wrong with multiple feeds at one breaker
Circuit design does not have to be as demonstrated in the guides
Safety is the criteria not unusual layouts
I believe that this is poor practise because of the inability to acurately test and record results.
Whilst I would agree that your zs can be reduced,by this method,it would take lighting circuits to be in excess of hundreds of meters for your disconnection times to become an issue.
Then there is to question of convenience and fitness of purpose,that requires that disconnection after a fault interupts the faulty circuit only.
I would also record a deviation on a pir.
 
M

matt20687

  • Thread Starter Thread Starter
  • #14
No i dont mean that. I mean that for example in a 6 Amp MCB you can have one 1.0 mm cable for that lighting ciruit and if you have a 32 Amp for a ringmain all you can have is the two ends of the ring in that one mcb.

Understand my madness ?

Sorry if i dont make sense
 
No i dont mean that. I mean that for example in a 6 Amp MCB you can have one 1.0 mm cable for that lighting ciruit and if you have a 32 Amp for a ringmain all you can have is the two ends of the ring in that one mcb.

Understand my madness ?

Sorry if i dont make sense
As previous poster said you can have a spur off the ring connected directly into mcb.
 
R

randyrat

  • Thread Starter Thread Starter
  • #16
As per previous poster....one circuit per mcb, with a spur allowed on the same terminals as a ring circuit. Other than that its one each. with lighting split upstairs/downstairs on two seperate mcbsTheres a one liner in the regs about limiting any single fault to minimise disruption...cant remember the wording exactly, but in order to comply this is the way to go.....
 

Des 56

-
Arms
Esteemed
I believe that this is poor practise because of the inability to acurately test and record results.
Whilst I would agree that your zs can be reduced,by this method,it would take lighting circuits to be in excess of hundreds of meters for your disconnection times to become an issue.
Then there is to question of convenience and fitness of purpose,that requires that disconnection after a fault interupts the faulty circuit only.
I would also record a deviation on a pir.
434.4
Fault current protection of conductors in parallel

A single protective device may protect conductors in parallel against the effects of fault currents provided that the operating charecteristics of the device results in its effective operation should a fault occur at the most onerous position in one of the parellel conductors

then read 433.1
433.2
regards Des
 
434.4
Fault current protection of conductors in parallel

A single protective device may protect conductors in parallel against the effects of fault currents provided that the operating charecteristics of the device results in its effective operation should a fault occur at the most onerous position in one of the parellel conductors

then read 433.1
433.2
regards Des
Hi Des,sorry,
As I don't have THE book ,I couldn't possably comment on your quoted regs.As you are no doubt aware,BS7671 is not enforceable by law,it is a code of best practice.You asked why I thought it was poor practice and I have given my reply as above. The temptation exists,when testing and verifying,to only test ONE branch of the circuit,especially,when we only have one box to fill in on the test sheet for the multicircuit,the inconvenience also exists in that suitable quidance is not provided.
 

Des 56

-
Arms
Esteemed
thanks mrloy99 you think the same way as me mate . I think 1 cable to each CB for testing the job i would likr to find some sort off reg for this but dont see one . The sparks that are doneing the job seem to think thay are right putting 3 and 4 cables in 1 breaker for there emg lights .Also they are doing fire alarms in the same job so i had i look 5 cables out 1 10 amp breaker 1 for there new fire alarm,2 intruder alarm ,3 central heating,4 roller shutter,5 socket in back shop
I think these guy have to have a think in what they are doing . STILL TO SEE TEST SHEET ON ALL THE 31 JOBS I HAVE LOOKED AT
I made a post defnding the use of multiple feeds in one breaker with example of a lighting circuit going off from the dist board in opposite directions

I was looking through this thread and read the quote above for the first time (must have not noticed initially)

Just to put my take on things and to be clear to all

Crazy (as described ) seems to be an understatement with regard to the above install
I probably would not hesitate to fail this job on an inspection
eg The fire alarm supply should not be affected by the failure of another circuit

The description above seems to be of get something working with little interest in design or standards

I posted this in case any of you thought that I may be defending this way of installing when in fact the standards I expect to find on a job would seem to be well above what has been described
My thoughts were on a typical single circuit eg a downstairs lighting circuit in a domestic
 
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M

markturnersisus

  • Thread Starter Thread Starter
  • #20
i think one circuit one mcb!i dont think you can feed a radial from the middle of the circuit as this makes it two radials.load is not the problem....its testing ..any r1 r2 will only cover at best half the circuit init...?....not got my copy of 17 yet though so could be wrong
 
S

super spark

  • Thread Starter Thread Starter
  • #21
The NICEIC do state that in the case of lighting circuits then its 1 conductor per protective device. Emergency lighting can be incorporated in to the circuit very easily, Its just lazy to insert a new circuit and expect it to comply. I am unclear as to how you would complete the details required on an installation certificate in such a circumstance. I would also mark this situation down as a contravention on a periodic inspection report as outlined by the esc in the best practice guide which has been agreed upon by all the regulatory bodies including; corgi, elesca, esc, niceic, nappit etc........... So if you dont take my word for it how about any one of them !
 
K

kung

  • Thread Starter Thread Starter
  • #22
the new regs state that only one wire is aloud in each mcb. Although it is stupid that as long as you join the cable outside of the CU then it is fine to have multiple circuits!
so does this mean radials instead of rings ?
 
M

marty1234

  • Thread Starter Thread Starter
  • #23
when i do emg lights i fit a double pole switch and light switch on a grid plate so i dont have 2 cables comeing out the breaker this means i can test the job the right way . today i was at an other shop that has a new fire alarm fitted last week and they have doubled up breaker the fire and intruder alarm from same 16 amp breaker this is a nic company doing this sort off work :eek:
 
S

super spark

  • Thread Starter Thread Starter
  • #24
when i do emg lights i fit a double pole switch and light switch on a grid plate so i dont have 2 cables comeing out the breaker this means i can test the job the right way . today i was at an other shop that has a new fire alarm fitted last week and they have doubled up breaker the fire and intruder alarm from same 16 amp breaker this is a nic company doing this sort off work :eek:
EXACTLY!!!!!!! its not rocket science is it lol

at least some of us use common sense :D
 
M

marty1234

  • Thread Starter Thread Starter
  • #25
supar spark it easy to do it right mate
 
E

electro

  • Thread Starter Thread Starter
  • #26
Hi
You are allowed to fit as many cables in to the circuit breaker as you deem safe as long as they belong to the same circuit, I personally don't think its good practice for testing or tracing out circuits thou. I would recommend you link elsewhere in the circuit.
Regards
 
M

marty1234

  • Thread Starter Thread Starter
  • #27
hi electro where in the reg book is this mate i cant find it
 
E

electro

  • Thread Starter Thread Starter
  • #28
Hi
reg 314 tells you one circuit per CB but interconnections can be made anywhere in the circuit. The inspection council (not NICEIC) explained it to me as what's the difference between at the CB and the first termination. I have had this problem before because everybody reads Reg 314 and think it means just one cable in to the CB. I would still make my connections elsewhere rather than the CB though.
Regards
 
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