Cooker Cable Downsized halfway through circuit

[tomodo]

Hi working at a house and noticed the cooker cable (6mm) has been joined above the kitchen units to a 2.5mm which then runs into a fused spur and to the cooker, circuit has been on a 32amp mcb all this time, I was thinking to just put the 6mm on a 16amp mcb in the fuseboard and note it on the test certificate that the cable has been downsized.. what are peoples views on this? and where would it be best noted on the certificate?

 

[Pete999]

How has the cable been connected at the transition from 6mm to 2.5mm???

 

[tomodo]

in a 30 amp junction box

 

[hightower]

Wouldn't an FCU count as your over-current protection for the 2.5mm cable meaning the 32A mcb is not ideal, but legal? Or am I getting my wires crossed?

 

[tomodo]

the fcu is after at the end of the 2.5mm so it goes 32amp mcb , 6mm cable, junction box, 2.5mm cable then to fcu

 

[hightower]

Yeah, but I thought you could have over-current protection, as in an FCU, downwind of the change of cable because it's still protecting the 2.5mm no matter where on the route it sits?

 

[Pete999]

What work are you doing in the house?

 

[tomodo]

I guess it would still protect then but just doesn't seem right, and I have changed the fuseboard and having to rewire parts of the sockets

 

[malcolmsanford]

Fault protection you might get away with as per reg(s) 434

Overload the same as 433.3.1 (ii)

So I would not be changing the MCB at all, as that 13 amp fuse(I'm guessing it is 13amp) for an exceedingly small cooker is limiting the load on that 2.5

 

[Pete999]

I guess it would still protect then but just doesn't seem right, and I have changed the fuseboard and having to rewire parts of the sockets

What prompted you to change the CU?

 

[tomodo]

Thanks for the replys very helpful , I might just swap the junction box for unswitched fused spur to put my mind at rest

 

[tomodo]

I got asked to do it was an old rewirable fuseboard

 

[hightower]

Thanks for the replys very helpful , I might just swap the junction box for unswitched fused spur to put my mind at rest

Wouldn't that create a discrimination issue?

 

[tomodo]

it would just be two fused spurs in a circuit

 

[Pete999]

it would just be two fused spurs in a circuit

What about the cb at the CU? if the fcu at the junction were to go open circuit and if it is not very accessible the the next sparky who comes in when the cooker is not working will find the cb OK but no 'juice at the cooker end, now that would be a head scratcher wouldn't it? rewire the whole circuit to be safe.