can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW shower

[mikejd]

Hi I have two 6mm csa cables in the loft each going back to a separate 30A mcb in the CU. One is redundant, the other goes to a broken 8.5kW shower. I want to fit a new 9.5kW shower and would like to join both 6mm cables together at a 50A dpst shower switch, then run a short length of 10mm csa cable from the switch to the shower. Can anyone see a problem with doing this. Both 6mm cables are approx same length (12m), there is a RCD in the CU.
Thanks

 

[hasel5]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Oh dear oh dear what a mess

 

[Wiresandthings]

Just do yourself a favour mate and call and electrician! What your planning on embarking on is just plain stupid! Plenty of safe solutions to this problem!

 

[Alex Ramage]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

But the (40A) current is shared down two 6mm cables (approx 20A down each). And each 6mm cable has its own 30A mcb back in the CU. From the 50A isolator pull switch near shower, where they join, the single cable to the shower is then 10mm. I cant see any over loading / overheating at all. Am I still missing something here.

Except for failure to comply with regulations why would this not be safe?
Any advice really appreciated
Thanks

OK buddy. Jokes over. You've had your fun now toddle off to some other trades website and wind them up

 

[jimjimjim]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

My god, i didn't realise until half way through he was talking about two seperate breakers bahahahahah. This has to be a wind up.

Jim

 

[Guest55]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

theres only 1 poster i can think of that covers this........

 

[Octopus]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Fingers crossed he's not a science/Physics teacher!

 

[MUFC1999]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

This thread is the classic example of how Dan needs to change the forum. If the OP is unwilling to attempt to answer some of the questions he should be put on a ban until he does.

Unfortunately this will not stop him doing what he thinks is OK.

Any basic understanding of the regs tells you this can't be done.

 

[mikejd]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Thanks to you who have replied genuinely to my question, without feeling the need to result to sarcasm. No I am not a qualified electrician and never claimed to be but I am both a physics graduate and electronics engineer. I never doubted that regs would not allow this to be done, though from an electrical theory perspective it is perfectly feasible, Its a shame very few replies seemed to go beyond 'you cant do it as it breaks the regs' and considered the theoretical reasons why...of which there are few.
Thanks again

 

[amlu]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

replace individual mcb for each cable for 1x mcb for both cables. 32a should do the job. connect both cables to it, then join them at other end and attach to a length of 10mm going into the shower.

 

[Deleted member 9648]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Thanks to you who have replied genuinely to my question, without feeling the need to result to sarcasm. No I am not a qualified electrician and never claimed to be but I am both a physics graduate and electronics engineer. I never doubted that regs would not allow this to be done, though from an electrical theory perspective it is perfectly feasible, Its a shame very few replies seemed to go beyond 'you cant do it as it breaks the regs' and considered the theoretical reasons why...of which there are few.
Thanks again

The main reason being that supplying a circuit with two separate MCB's creates problems with isolation. Another reason is that two MCB's in parallel are an unknown quantity for short circuit and overload protection. You cant do it. End of.

 

[micknew]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Thanks to you who have replied genuinely to my question, without feeling the need to result to sarcasm. No I am not a qualified electrician and never claimed to be but I am both a physics graduate and electronics engineer. I never doubted that regs would not allow this to be done, though from an electrical theory perspective it is perfectly feasible, Its a shame very few replies seemed to go beyond 'you cant do it as it breaks the regs' and considered the theoretical reasons why...of which there are few.
Thanks again

Nobody went into it because its such a stupid dangerous thing to do, get a sparks in.

 

[Alex Ramage]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Figured as much. You need a physics nerd website my son. One where your theories can be appreciated and discussed out with the confines of the regulations and common sense which shackle us mere mortal sparks

 

[Engineer54]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Also further to ''amlu's'' post #39 There are very strict requirements for ''Parallel'' supply wiring, among others, one very important requirement, being that Both cables must be of exactly the same length and follow the same route. I doubt very much if this will be the case in your situation from what you have told us.

And no you're thoughts on a dual supply from 2 separate OCPD is not perfectly feasible from a theory perspective. Until you know the theory behind the design of a circuit, it's advisable you don't make speculative claims that can't be substantiated!! ....So Again, DONT DO IT!!!

 

[PEG]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

I knew if i waited long enough,retribution for my unacceptable 1979 excuse for not returning my physics homework,would be forthcoming...take that teacher...on a lighter note,just because a method is a possibility,does not mean there are not other reasons why it should not be attempted. These reasons are sometimes practical,and sometimes dictated by regulation,now and again it is both. Imagine if someone posted on a serious driving forum,if it was possible to drive around all day long,and just use the handbrake to stop the vehicle. You could,with care,do this,but is this sensible? Now off you go...DON'T RUN IN THE CORRIDOR!:goofy:

 

[Geordie Spark]

Re: can two 6mm csa cables each with 30A mcb in joined at 50A dps to supply 9.5kW sh

Sounds great. You could always connect a fan to the circuit as well ; )

Aye .. and one of them electric body driers as well and don't forget the spur for the shed and outside light.