Cooker connection unit to hob cable size

[Gringoking88]

Hi all,

I have just been to a job where the existing hob is wired in using 2.5mm heat resistant cable, the hob is rated at 6000w. I calculate this to need a 4mm cable, however, was challenged by someone, in the end I called NICEIC who stayed neutral and said it "might be ok, what do the instructions say" instructions dont specify the cable size needed.

What size cable would you guys use?

Many thanks in advance,

M

 

[Pretty Mouth]

How have you calculated your design current?
What breaker is protecting the cable?

 

[Gringoking88]

How have you calculated your design current?
What breaker is protecting the cable?

Its on a 32amp breaker, supplying both cooker and hob. The previous hob was also rated at 6000w and on the same cable, no sign on heat damage.

 

[Pretty Mouth]

And your design current?

 

[Gringoking88]

And your design current?

The hob is rated at 6000 w so 25amp

 

[Pretty Mouth]

6000/230=26A

Diversity: read Appendix A in your OSG, and the allowance for cookers is in table A1. This will give you your design current for the circuit. Come back to us with that.

Hang on, there's an oven on it as well?

 

[Gringoking88]

6000/230=26A

Diversity: read Appendix A in your OSG, and the allowance for cookers is in table A1. This will give you your design current for the circuit. Come back to us with that.

Hang on, there's an oven on it as well?

Yes there is a 13 amp oven. I understand the diversity part e.g. first 10 amp plus 30% of the remainder, however, the circuit is pre existing, I am referring to the cable literally the connection point to the hob.

 

[Gavin John Hyde]

What do the manufacturers instructions say?

 

[Gringoking88]

Yes there is a 13 amp oven. I understand the diversity part e.g. first 10 amp plus 30% of the remainder, however, the circuit is pre existing, I am referring to the cable literally the connection point to the hob.

Oh and there is a socket so rated current is

What do the manufacturers instructions say?

They dont, they just specify the heat resistant cable and not the actual size, I called them (Zanussi) and they said they didnt know and to email in.

 

[Pretty Mouth]

Ah I see. I presume ref method C?

From about P400 of the BS7671 you'll find the tables for current carrying capacity for various cables. Yours would be 2.5mm, multicore, presumably 90deg if it's heat resistant, and it's not armoured. Have a butchers and tell us the CCC for your cable

 

[Gringoking88]

Ah I see. I presume ref method C?

From about P400 of the BS7671 you'll find the tables for current carrying capacity for various cables. Yours would be 2.5mm, multicore, presumably 90deg if it's heat resistant, and it's not armoured. Have a butchers and tell us the CCC for your cable

26 amp when in free air. I guess that answers the question, but is very close to the mark.

 

[Pretty Mouth]

which table did you get that figure from?

 

[buzzlightyear]

table 4e2a 2.5 mm cable .

 

[Pretty Mouth]

table 4e2a 2.5 mm cable .

You make it too easy for him Buzz.

Lastly, what does Note 1 to table 4E2A say?