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

 

[SimpleSimon]

So in your case it would be 230/5300= 23a
First 10a than 30% of remainder (23-10=13) 13/100=0.13x30=3.9a. Than add your original 10a on gives you 13.9a, and if you have a socket add 5a so your total would be 17.9a. 2.5 would still be ok but you run future risks if anything changes or they deciede to open their doors to the homeless

(PS this calculation does not take into account any factors for the cable run)

 

[GLENNSPARK]

and if adding up multiple loads on a single circuit.....so lets say that you have several cookers all fed from one circuit...then you would apply diversity to EACH LOAD SEPERATELY...then add up the total......

 

[egginyourface]

ok, so 30% of the 23 amps is 6.9 amps


so 16.9 amps as you said in your earlier post right

 

[GLENNSPARK]

this of course will dictate the size of overcurrent device you will use at origin....which in turn will give you the correct cable size to use.....installation method, ambient tempreture, grouping and length of run taken into account of course.....

 

[egginyourface]

sorry i meant 30% of the 13 amps


The cable run is about 12metres long and run in yt2 trunking with a 10mm earth for the gas. Only about 1 metre of it is actually buried

 

[telectrix]

ok, so 30% of the 23 amps is 6.9 amps


so 16.9 amps as you said in your earlier post right

NO. 10A + 30% of remainder (13A, not23A)

 

[ebow72]

there is a hob but its on a seperate 6mm

Might be a stupid idea and I don't know the rating of the hob, but is there enough slack of the 6mm, to swap over to the cooker and vica versa...
I am still learning so please don't make me brew up

 

[GLENNSPARK]

it might be a start to look at app. A starting page (109) in the osg (green)....table A1....

 

[WPD Lad]

Might be a stupid idea and I don't know the rating of the hob, but is there enough slack of the 6mm, to swap over to the cooker and vica versa...
I am still learning so please don't make me brew up

Hobs are normally rated higher than ovens, something in the order of 7kw

 

[WPD Lad]

If its in a conduit surely it's easy enough to swap out for 4 or 6mm

 

[TaffyDuck]

Diversity on a cooker works fine until Xmas day when they trip out. personally I think regs are out of date on this one. Take a 10 kW electric range cooker. 10kW/230V= 43 amps. 10 amps plus 30% remaining load (approx 9.9amps) =19.9 amps so 2.5mm twin and earth on a 20 amp, dont think so. "At the installers discretion" is a term we ought to use more. On top of that you`ve got an appliance that draws for long periods of time allowing heat to build up in the circuit. Its not like a kettle that runs for a couple of minutes at a time. 6 or 4mm on this OP specs every time for me,

 

[Dave 85]

Bung it on the 2.5 on a 20A breaker with 20A DP iso. You're happy, regs are satisifed and client doesn't feel shafted and may actually call you again. I really don't understand this attitude of 'charge the client for an unnecesary job just to punish them for changing their mind.' Repeat business is good no?

 

[GLENNSPARK]

Diversity on a cooker works fine until Xmas day when they trip out. personally I think regs are out of date on this one. Take a 10 kW electric range cooker. 10kW/230V= 43 amps. 10 amps plus 30% remaining load (approx 9.9amps) =19.9 amps so 2.5mm twin and earth on a 20 amp, dont think so. "At the installers discretion" is a term we ought to use more.

well on such a load then...yes....it would be up to the designer as to the right action to take here.....short of treating it as a commercial load...100% of the first load....80% of the second and 60% of remaining appliances....

 

[ample current]

so what does the fl mean in the OSG (red one page 97)?? and i quote "10A +30% of fl of connected cooking appliances.........."

 

[GLENNSPARK]

full load...