M
MikeBa
First post on forum, so go easy on me please!.
I am looking to add a hob to an existing installation –details as follows:-
Existing oven – 3 kW – adding 7 kW hob
1998 build
32A MCB type B feeding 6.0mm2 t&e radial circuit about10m length clipped to wall, behind plasterboard connecting to 45A DP isolator with13A plug – above work top – closed to oven/ hob area.
From DP isolator 2 x 4.5mm2 t&e to under worktop – one to13A unswitched socket supplying the (present) gas hob ignition – the other to45A cooker connection unit.
From the CCU a 2.5mm2 t&e to oven.
With diversity the proposed addition works – (3000W + 7000W)/240V – 41.7A
First 10A + 30% remaining + 5A for socket = (41.7A-10A) x .3+ 10A + 5 A = 24.5A < 32 A
My concern is that the 2 x 4.5mm2 from DP isolator and 2.5mm2from CCU are being protected by a 32A MCB – not to regs and one of the 4.5mm2.t&ewould not be sufficient to supply the 7 kW hob.
To correct this I propose linking the 2 x 4.5mm t&e intoa twin CCU (discussed on this forum) and connecting the oven and hob into this.Probably replacing the 2.5mm2 t&e to the oven with 6.0mm2. This will placeat least 6.0mm2 to the complete circuit and allow the diversity calc to bevalid all the way to the CCU.
The hob requires a flexible high temp (90 deg) cable that I amtrying to source (various threads on this forum relating to the rarity).
Thanks in advance for the help!.
I am looking to add a hob to an existing installation –details as follows:-
Existing oven – 3 kW – adding 7 kW hob
1998 build
32A MCB type B feeding 6.0mm2 t&e radial circuit about10m length clipped to wall, behind plasterboard connecting to 45A DP isolator with13A plug – above work top – closed to oven/ hob area.
From DP isolator 2 x 4.5mm2 t&e to under worktop – one to13A unswitched socket supplying the (present) gas hob ignition – the other to45A cooker connection unit.
From the CCU a 2.5mm2 t&e to oven.
With diversity the proposed addition works – (3000W + 7000W)/240V – 41.7A
First 10A + 30% remaining + 5A for socket = (41.7A-10A) x .3+ 10A + 5 A = 24.5A < 32 A
My concern is that the 2 x 4.5mm2 from DP isolator and 2.5mm2from CCU are being protected by a 32A MCB – not to regs and one of the 4.5mm2.t&ewould not be sufficient to supply the 7 kW hob.
To correct this I propose linking the 2 x 4.5mm t&e intoa twin CCU (discussed on this forum) and connecting the oven and hob into this.Probably replacing the 2.5mm2 t&e to the oven with 6.0mm2. This will placeat least 6.0mm2 to the complete circuit and allow the diversity calc to bevalid all the way to the CCU.
The hob requires a flexible high temp (90 deg) cable that I amtrying to source (various threads on this forum relating to the rarity).
Thanks in advance for the help!.
