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Discuss What size cooker feed? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

C

Cirrus

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Was wiring a kitchen yesterday and the guy is having an electric range cooker installed and I needed to get a feed to it. The councils ask us to put in 6mm t&e as standard but will sometimes agree to 10mm. However, this cooker is rated at 14.1kW!!!! I calculated that at about 61A. Now surely I can't be expected to try and install 16mm t&e and worse still - terminate it in the cooker?:eek: I appreciate I have to factor in diversity but -
What is worse, his main cut out is only 60A and he also has a 10kW shower, 4 ring mains as well as the usual lighting circuits, water heater etc..
The council will not pay for 16mm so instructed me to pull in 10mm and leave it at that. Your thoughts chaps?
 
R

rumrunner

  • Thread Starter Thread Starter
  • #2
Good question ,how does it work out if you wire it in micc,maybee you can satify everyone that way
i dont do this type of work and didnt bother finishing the 16 edition course ,due to head blow off ,so please treat it as a sugestion rather tham a solution
atvbitwww
 
C

Cirrus

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  • #3
Nah, they wouldn't entertain pyro as it's domestic.
 
G

Grae79

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  • #4
what's the diversity calc for cookers? don't have osg to hand.
 
C

Cirrus

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  • #5
Nah, neither do I and yesterday it was a case of too many differing opinions. AGA reckon 10mm is fine and even 6mm would just about be ok too!
 
G

Grae79

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  • #6
was just looking at some ranges on t'interweb....similar sort of spec...they recommend connection through 45A conn/switch.

how long's the run?
 
G

Grae79

  • Thread Starter Thread Starter
  • #8
not too bad really...i mean 10mm's rated at 63A using ref method 1. so with diversity in effect would've thunk would be ok, but don't quote me on that. better off doing sums and what-not, obviously.
 
E

EasyFox

  • Thread Starter Thread Starter
  • #9
what's the diversity calc for cookers? don't have osg to hand.
First 10amp of rated current then 30% of the remainder
Dont forget to add 5amp if sso on ccu.

25amp with diversity
30amp if socket on ccu
 
G

Grae79

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  • #10
did u pluck that off the top of ur head Easy?
 
R

rumrunner

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  • #16
Sorry CIRRUS NOT WISHING TO DISAGREE BUT I CANT SEE WHY YOU CANT USE MINERAL FOR DOMESTIC WORK ,IVE USED IT FOR LISTED BUILDINGS AND FOR COMERCIAL KITCHINGS AND AS LONG AS IT IS INSTALLED CORRECTLY IS THE BEST JOB YOU CAN HAVE ,I WOULD DO IT ANYWAY AND BILL WHOEVER
ATVBITWWW
 
C

Cirrus

  • Thread Starter Thread Starter
  • #17
nah, MI is old hat now and only used in chemical situations / petrol stations etc. There is no way anyone would consider using it on domestic nowadays
 
S

Shakey

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  • #18
Easyfox is right with his diversity calcs;)

dont you guys use this as standard?????

i have lost count of the number of sparks i have had to explain this too, what is even more surprising is the number of them that GENiUNELY hadnt heard of it before.:confused:

And why 10mm?

or even 6mm?

or even 4mm for that matter??????

if theres no BS1363 outlet in the CCU, by Ib In Iz you could put it on a 25A 60898 and run in 2.5 assuming method 1 (27A)

even 4mm could be considered as 'throwing excessive copper' at the problem!!!!!

ho, hum. we live and learn!:rolleyes:
 
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G

Grae79

  • Thread Starter Thread Starter
  • #19
go for it....be able to cook some wee roast tats on the 2.5 when you're making sunday dinner.

where do you get the 25A 60898's from?
 
C

Cirrus

  • Thread Starter Thread Starter
  • #20
Well, the standard is to use 6mm in domestic situations and this is why the council spec 6mm with 10mm for larger cookers. We have to use 10mm as a matter of course on our showers too. We don't normally have to worry about applying diversity or any calcs because the emphasis on council jobs is speed so the brain work is generally done for you. You aren't trying to tell me thet you would be happy recommending 2.5mm to a customer with a cooker rated at 61A max?
 
M

markthespark

  • Thread Starter Thread Starter
  • #21
id stick a 10mm in and bang it on a 40amp breaker shud do the trick
 
C

Cirrus

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  • #22
Yeah, I have pulled in 10mm and ordered a 45A RCBO
 
S

Shakey

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  • #23
Well, the standard is to use 6mm in domestic situations and this is why the council spec 6mm with 10mm for larger cookers. We have to use 10mm as a matter of course on our showers too. We don't normally have to worry about applying diversity or any calcs because the emphasis on council jobs is speed so the brain work is generally done for you. You aren't trying to tell me thet you would be happy recommending 2.5mm to a customer with a cooker rated at 61A max?

Cirrus and Grae

think you may be missing the point gents.

Firstly why would cooking the sunday dinner make any difference.? So even if its an electric hob, main oven goes on, gets up to temp, cycles on and off, some time later rings go on the boil the spuds THIS IS CALLED DIVERSITY. 61A max would be oven, grill, fan everthing, and most ovens wont let you!!! (they have this thing called a sector switch on the front!)

And Cirrus, I assume you are familiar with ring mains. So lets say you've got a small ring with 10 doubles on it. That's 26A per outlet, so that's 260A max for the ring - but you are happy to reccomend that to a customer on 2.5 mm cable???? even connected as ring thats only 54A!!! But we dont pull 260A do we? and why not? DIVERSITY

sort of knocks your 61A max into a cocked hat, dont it!!!!

Note to forum members: look up diversity in the dictionary!!! Or even BS7671!!!!

And no, i generally wouldnt use 2.5 for a cooker, because it doesnt allow for changing the appliance to a larger one later, and is cutting it 'to the wire', but it doesnt mean i would blindly throw in 6 or 10mm either

And yes you CAN get 25A Type B 60898's. Trouble is, not many people use them (or know the exist!)

And this whole thread has proved my point. Gentleman, if we also blindly throw 6mm into a cooker, 10mm into a shower and only ever use 6, 20, 32 or 40 A MCB's we get to the point where we lose the skill to actually work these things out when we need to - as proved here.

Now and again just sit down and do a calc on that circuit, before you just become, effectively, electrical labourers

i get annoyed when i see this trade dummed down to the point where anyone could size up a circuit just by reading a leaflet from B&Q or Wickes:mad:

Rant over with

And well done to Easyfox for stating a simple diversity equation that should be common knowledge;)
 
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G

Grae79

  • Thread Starter Thread Starter
  • #24
are you working to the 17th edition then cirrus?

and as for that Shakey...possibly the most patronising reply i've read yet....well done u! :D
 
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S

Shakey

  • Thread Starter Thread Starter
  • #25
are you working to the 17th edition then cirrus?

and as for that Shakey...possibly the most patronising reply i've read yet....well done u! :D
Sorry Grae:eek:

didnt mean to patronise, i'm in crap mood because her car just failed the mot. need new discs and pads. Threw the money to the guy to get it done 'cause i just dont have the time. Then sat there for an hour and a half waiting to get it done. Then realised i could have done it myself in that time anyway, and saved myself a wodge.:mad:

And now she's onto me to clean the cooker......which is probably on 2.5mm cable:D
 
C

Cirrus

  • Thread Starter Thread Starter
  • #26
Well that told me! I agreew ith you on one point Shakey - it is too easy to simply get sucked in as an electrical labourer on these council rewires as all the thinking has been done for you. That is why I liked commercial and Ind work so much as it made me think. Still, rewires pay well.

Grae - I am working to 16th until June when 17th officially comes in I guess. Why?
 
E

EasyFox

  • Thread Starter Thread Starter
  • #27
And well done to Easyfox for stating a simple diversity equation that should be common knowledge;)
Why thank you:cool:
I did have to re-read the first posts, thought it was a wind up .....or am I just sad being able to remember the diversity calc/equation :eek:

Have just read the other posts & feel a bit of a numpty because I also did the cable calcs but not knowing what the ocpd was didnt post the calcs.
Anyway I binned the idea of using 2.5mm purely on the grounds of...well I dont know why.. so a lesson learnt there, nice one shakey just goes to proove dont just do it because thats the way its always been done :)

So I was left with 6mm or 4mm (didnt bother with 10mm why waste money) & because I'm in business to make a profit I went for 4mm :D .

Well that was all hypathetical but enjoy working such things out...keeps the old grey matter ticking over, as Shakey said we can all just put 10mm or 6mm in as thats how its been done & just passed down to the next generation of sparks, & the art of working such things out is slowly being lost to your average house basher.

Thinking back to an old college lecturer he always said
"Using diversity sometimes means smaller conductors, smaller protective devices, smaller switch gear but always a bigger proffit"
 
C

Cirrus

  • Thread Starter Thread Starter
  • #28
Seems the trade is changing and not necessarily for the best:(
 
G

Grae79

  • Thread Starter Thread Starter
  • #29
Grae - I am working to 16th until June when 17th officially comes in I guess. Why?
just curious...cos you said were putting it on RCBO.
 
C

Cirrus

  • Thread Starter Thread Starter
  • #30
The council have insisted in this case because there are no spare ways in the new board on the rcd side so they want it on non-rcd but with an rcbo in place.
 
S

Shakey

  • Thread Starter Thread Starter
  • #31
Cirrus, the RCBO in place for what?

are you saying they wanted the rcbo in for the cooker?

make sense i suppose, they'll all be on them soon!!!
 
W

wayne

  • Thread Starter Thread Starter
  • #33
no he pulled that from the osg page 85 blue book
 
E

EasyFox

  • Thread Starter Thread Starter
  • #35
if the house only has a 60a cut out,and youve got a shower,4 rings and the rest to deal with.Surely the main fuse would overload?
& we are back to Diversity.

no he pulled that from the osg page 85 blue book
From memory actually but you are correct it is on page 85 of the BROWN (binned the blue ages ago) osg :).
 
S

Shakey

  • Thread Starter Thread Starter
  • #37
Everydays a school day luke, guess we are all learning!
 
D

drayton

  • Thread Starter Thread Starter
  • #38
I did a kitchen once and had to put in a 13A f/spur for the elctric range. As per aga instructions . . the thing was switched on permantly and just slowly heated up like a big storage heater.go figure?
 

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