4mm radials

[eastweb]

Hi there.

Is there a problem using two 4mm radials in a kitchen using the same mcb as opposed to a 2.5mm ring?

Thanks.

 

[Johno]

Why use same MCB?

 

[Hawk81]

yeah why use the same mcb? i dont see the advantage of two radials on the same mcb as opposed to a ring main. if a fault develops the whole kitchen will go off. plus anyone else looking into the cu will maybe think it is supposed to be a ring

 

[Paul.M]

Reg 431.1.1 states:- detection of overcurrent shall be provided for "all line conductors" and shall cause the disconnection of "the conductor" in which the overcurrent is detected, but not the disconnection of the other line conductors..... 2 radials = 2 mcbs. Safe practice, no confusion for the next sparky looking in the cu and everyone is happy. Kitchen, rcd x 2 maybe?

 

[JUD]

Reg 431.1.1 states:- detection of overcurrent shall be provided for "all line conductors" and shall cause the disconnection of "the conductor" in which the overcurrent is detected, but not the disconnection of the other line conductors..... 2 radials = 2 mcbs. Safe practice, no confusion for the next sparky looking in the cu and everyone is happy. Kitchen, rcd x 2 maybe?

Paul, take a look at App. 15 in the BRB at the 4mm² radial. As long as you use 4mm² T&E you can spur off to more than one socket.

The picture shows it being spurred off a double socket outlet, which IMO is no different to spurring straight off the OPD.

However, I agree with the above. I can't see why anyone would want to do it this way as opposed to a ring circuit.

 

[Paul.M]

Agree with appx 15 that's spurring from the circuit not the mcb. OSG appx 8 says it is ok to spur from the cu but only one single or double socket. It would be good to have more info, is the kitchen an awkward layout?

 

[eastweb]

Hi, sorry for delay in replying - refurb job and working all hours.

I went down the ring main route in the end. The question was asked due to the lack of space for cables in the existing run and didnt want to "loop back" to other side of the kitchen.

Thanks for all the replies.

 

[ian.settle1]

Further to what has been said above if I came at a later date and saw 2 x 4mm out off same breaker I would assume it was a ring and when testing for ring continuity and not find any I would start looking for the break in the ring.

 

[ezzzekiel]

my view also