5.3 kw double oven on a 20 amp fuse with 2.5 cable

[egginyourface]

evening all,

I was told to run 2.5 cable from fuseboard to supply a 3.5 kw single oven. Job is done....

Now they've said theyre going to put in a 5.3kw double oven in.

Question i have is can I apply diversity to this and keep 2.5t+e or do i need to run a new 6mm,

advice would really appreciated

thanks

 

[a1guvner]

They want to change the spec, time for a variation order and some more dollar for you

 

[TaffyDuck]

23 amps. Well technically 20amp fuse still exists so the cable is protected subject to normal de-rating considerations. Pushing it a bit IMHO. I think I`d recommend an upgrade in writing so if/when you have to go back to upgrade your covered. Sometimes these ovens have 5.3kw or something on them and that includes 3 elements say 2x grill and 1x rear circular fan element. As its unlikely or impossible perhaps to have the rear fan oven element on at same time as the grill you would be under 20 amps again

 

[TaffyDuck]

Cant say I can remember a job in a kitchen when it didnt change a bit so i usually bung 6mm in. These flippin electric range cookers are the nightmare at 10-11 kW.

 

[telectrix]

as a1guvner says. alteration in design, extra work, extra cost.

 

[ample current]

the diversity allowance for cooking appliances in a household is 10amps + 30% f.l ( full load if i remember right ) +5amps if the cooker outlet has an incorperated socket outlet.

 

[telectrix]

which gives around 15A without a socket outlet ( top of head as calculator not to hand). so 2.5mm on 20A is adequate. problem would arise if they added a hob or changed to oven for a higher rated one.

 

[ample current]

which gives around 15A without a socket outlet ( top of head as calculator not to hand). so 2.5mm on 20A is adequate. problem would arise if they added a hob or changed to oven for a higher rated one.

nearly telectrix 16.9 amps to be precise.

 

[egginyourface]

there is a hob but its on a seperate 6mm

 

[telectrix]

just worked it out. 5300/230 = 23A

10A + (0.3 x 13 ) = 13.9A. where did 16.9 come from?

 

[egginyourface]

Can someone give me a step by step guide on how to calculate diversity as i havent used it for about 4 years...

 

[telectrix]

1.divide the watts by 230 to give a total load current figure.
2. apply diversity: 10A + 30% of remainder = answer. add 5A if a socket outlet is incorporated.

 

[GLENNSPARK]

should add here that watch out for old BS3036s...as this affects the CCC of cables....as in for 2.5mm flat T&E on a BS EN 60898=27A....for BS3036=24A.........

 

[ample current]

just worked it out. 5300/230 = 23A

10A + (0.3 x 13 ) = 13.9A. where did 16.9 come from?

are you saying its 30% of whats left of the 23 amps after taking the 10 off? I thought the fl (in the osg) meant full load so 30% of 23 amps (not 13amps) ie 6.9 amps plus the 10
equalling 16.9

 

[GLENNSPARK]

its the first 10A...then 30% of whats left......then if theres a BS1363 outlet incorperated into the double pole iso for the cooker....then just add 5A......