Cooker diversity with SEPARATE oven/hob

[Justme761]

Hi all,

Looking at replacing kitchen. Current setup is 2.2kw oven, 5.6kw hob.. total = 7.8kw on 6mm cable, back to a 40a breaker. The current cable run is short..

2m from CU, in breezeblock/plaster..
2m clipped direct, to a 45a switch (for oven in tower)..
3m spurred from that, on more 6mm, to another 45a switch (for hob)..

Want to replace this with a 4.4kw double oven, same 5.6kw hob, total = 10kw.

Applying diversity, all looks good...

10,000 / 240 = 41.67 amps.. -10 = 31.67 amps * 0.3 = 9.5 amps + 10 = 19.5 amps

BUT, it's dawned on me this is a separate oven/hob combo, not a big all-in-one thing. Does this make any difference to the calculation? I'm just thinking if this was an all-in-one type, it'd have knowledge/control over what its own heating elements were doing, so would presumably ensure it didn't use more than the 10+30%, which is I guess what manufacturers quote to people putting the regs together?

Hope that makes sense - basically, is the calculation any different when it's an all-in-one oven/hob, or separate oven and hob?

Many thanks,

Shaun.

 

[Andy78]

You should perform the calculation separately for each appliance, and also take heed of the manufacturer's installation instructions as these may stipulate minimum connection particulars above that of the calculated diversity values.

I can't see you having a problem though.

 

[snowhead]

How many cooks are going to be using this cooking equipment at any one time?

 

[Justme761]

You should perform the calculation separately for each appliance, and also take heed of the manufacturer's installation instructions as these may stipulate minimum connection particulars above that of the calculated diversity values.

I can't see you having a problem though.

Hi Andy78,

Thanks for the input, that makes sense. Doing for each I get..

4,400 / 240 = 18.33 amps.. -10 = 8.33 amps * 0.3 = 2.5 amps + 10 = 12.5 amps
5,600 / 240 = 23.33 amps.. -10 = 13.33 amps * 0.3 = 4 amps + 10 = 14 amps
TOTAL = 26.5 amps (Difference +7 amps)

..which looks like it'll still be fine on 6mm and 40amp breaker?

 

[Justme761]

How many cooks are going to be using this cooking equipment at any one time?

Hi Snowhead,

Just the one cook involved, but I regularly taste her kitchen output, and some can be on the ropey side. But I'm not sure if I could describe her as 0.75 of a cook?

Is the thinking that if it's just one person, usage won't be all heating elements at once - so all good?

 

[Justme761]

You should perform the calculation separately for each appliance, and also take heed of the manufacturer's installation instructions as these may stipulate minimum connection particulars above that of the calculated diversity values.

I can't see you having a problem though.

PS. Have checked one of the manuals online, the one for the oven not bought yet. Skimpy little thing. Nothing mentioned at all bar the wattage and the cable that should be used (6mm) but of course that's not with the hob in the equation. Will try and find instructions for hob online as it's one we've had for a while and the original is long gone....

 

[MARV]

Hi Andy78,

Thanks for the input, that makes sense. Doing for each I get..

4,400 / 240 = 18.33 amps.. -10 = 8.33 amps * 0.3 = 2.5 amps + 10 = 12.5 amps
5,600 / 240 = 23.33 amps.. -10 = 13.33 amps * 0.3 = 4 amps + 10 = 14 amps
TOTAL = 26.5 amps (Difference +7 amps)

..which looks like it'll still be fine on 6mm and 40amp breaker?

Hi All,
Newbie has a question, is there a reason for sticking with 40A breaker and not dropping down to a 32A?

 

[Leesparkykent]

Hi All,
Newbie has a question, is there a reason for sticking with 40A breaker and not dropping down to a 32A?

Because they are fixed loads so overcurrent protection can be omitted.

 

[MARV]

Because they are fixed loads so overcurrent protection can be omitted.

I'm still on a learning curve but what does that exactly mean please. Out of interest could it go on to a 32A?