how many cables can you fit in to a circuit breaker

[randyrat]

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]

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

 

[mrloy99]

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]

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

 

[markturnersisus]

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

 

[super spark]

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 !

 

[kung]

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 ?

 

[marty1234]

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

 

[super spark]

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

EXACTLY!!!!!!! its not rocket science is it lol

at least some of us use common sense

 

[marty1234]

supar spark it easy to do it right mate

 

[electro]

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

 

[marty1234]

hi electro where in the reg book is this mate i cant find it

 

[electro]

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