Hi all. Electrical novice here so I'll try to explain this as best I can. I've just bought a new electric cooker that has a 10kw total power output and must be hardwired to a 45amp cooker circuit with the usual isolation switch above the kitchen work surface. I've had a look at the back of the isolation switch socket in my kitchen which says it is a "45A double pole switched socket", but I cannot see any ratings on the cooker circuit's MCB switch in my home's main electrical fuse box. (There is an RCD switch in it that says total rating is 80A for all the MCBs in the box). Can I therefore assume that the cooker circuit by itself is 45A because of whats printed on the back of the isolation switch socket in the kitchen?
Cooker circuit rating
- Thread starter Stepho
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Hi Dave,
Pic attached. I tried to get it as in focus as I could but the lighting is dim on the cupboard and using the flash overexposes everything. Just incase you cant make it out properly:
Green 1= shower
Green 2= cooker
Green 3= sockets
Green 4= water boiler
Green 5 & 6 are empty
Red 1 = lighting
Red 2 = smoke detector.
Pics below are: main house fusebox, kitchen isolator switch, cooker conection point (cover), cooker connection point (inside).
[/img]
Pic attached. I tried to get it as in focus as I could but the lighting is dim on the cupboard and using the flash overexposes everything. Just incase you cant make it out properly:
Green 1= shower
Green 2= cooker
Green 3= sockets
Green 4= water boiler
Green 5 & 6 are empty
Red 1 = lighting
Red 2 = smoke detector.
Pics below are: main house fusebox, kitchen isolator switch, cooker conection point (cover), cooker connection point (inside).
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Thanks for the info. I didn't realise the B32 number corresponded to the rating.
So does this mean that I would need to have some hefty electrical/rewiring work done in order to even be able to have the cooker connected? If so, what exactly?
So does this mean that I would need to have some hefty electrical/rewiring work done in order to even be able to have the cooker connected? If so, what exactly?
Thanks for the info again. I'll get somebody out next week (it seems like this new cooker might not be the bargain I thought it was!).
BTW, I forgot to post the pics of the connection point and switch in the kitchen in my earlier post, which I've just added. Dont suppose it'll make any difference now though if the MCB is the wrong rating anyway.
BTW, I forgot to post the pics of the connection point and switch in the kitchen in my earlier post, which I've just added. Dont suppose it'll make any difference now though if the MCB is the wrong rating anyway.
if we assume (and you never know 
) that teh cable installed was matched to the 32A MCB you can, for the moment, connect your cooker to the existing outlet. The result will be that most of the time, the cooker runs way under its max power.
However, when you are cooking e.g. a large christmas family dinner, using all rings and both ovens, you can expect an overload which will trip the MCB. This will be inconvenient. So get some recommendations from friends and neighbours for a local electrician, and, when phoning, ask him if he is a member of a self-certification scheme, which one, and what name he is registered under (you can check this, and he will not be offended at being asked... unless he is unqualified).
there is a formula for calcuating anticipated cooker loads which will say it is OK to put your big cooker on a 32A supply... but the formula copes with typical use, not the Christmas Dinner I mentioned
) that teh cable installed was matched to the 32A MCB you can, for the moment, connect your cooker to the existing outlet. The result will be that most of the time, the cooker runs way under its max power.However, when you are cooking e.g. a large christmas family dinner, using all rings and both ovens, you can expect an overload which will trip the MCB. This will be inconvenient. So get some recommendations from friends and neighbours for a local electrician, and, when phoning, ask him if he is a member of a self-certification scheme, which one, and what name he is registered under (you can check this, and he will not be offended at being asked... unless he is unqualified).
there is a formula for calcuating anticipated cooker loads which will say it is OK to put your big cooker on a 32A supply... but the formula copes with typical use, not the Christmas Dinner I mentioned
Thanks for that John. To be honest, although I am never likely to be using absolutely everything on the cooker at the same time, I think I would prefer not to run the risk of tripping it (just on the offchance I am ever doing a big meal for a cast of thousands).
Is there an easy way that I myself can tell what size wiring is in there at the moment. Is this the wiring going out of the MCB and into the kitchen isolation socket?
Is there an easy way that I myself can tell what size wiring is in there at the moment. Is this the wiring going out of the MCB and into the kitchen isolation socket?
10kW cooker = 43.5A. (The rating will almost certainly be a 240V one, but this gives worst case).
(43.5 -10) x 0.3 + 10 + 5 for the socket = 25.05A, so on that basis the 32A circuit has plenty of headroom.
1) With the power off measure the diameter of the Live or Neutral conductor - the actual copper part. Not one strand - the whole lot will be OK, provided it's still twisted into an overall round shape. Then calculate the cross-sectional area.
2) Measure the external size of the complete cable and compare it to sizes given here.
It's probably 6mm²...
Yup.
6mm generally has a solid CPC wheras 10mm and 16mm have stranded CPC's like the phase and neutral.
6mm generally has a solid CPC wheras 10mm and 16mm have stranded CPC's like the phase and neutral.
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I appreciate what folk say about cookers being best installed taking flc into account. I too would do this, given the opportunity.
However, for installations where rewiring is not practical, I believe it is perfectly acceptable to use diversity to allow a larger load to be connected than would normally.
The worst case scenario would be an overload situation, with the breaker tripping. However, in my experience at least, even taking the good ol' festive season into account, you'd have to be unlucky to have that happen.
That's my opinion, anyhow...
However, for installations where rewiring is not practical, I believe it is perfectly acceptable to use diversity to allow a larger load to be connected than would normally.
The worst case scenario would be an overload situation, with the breaker tripping. However, in my experience at least, even taking the good ol' festive season into account, you'd have to be unlucky to have that happen.
That's my opinion, anyhow...
Ban,
"1) With the power off measure the diameter of the Live or Neutral conductor - the actual copper part. Not one strand - the whole lot will be OK, provided it's still twisted into an overall round shape. Then calculate the cross-sectional area"
Taking issue with you on this one mate.
Measure one strand, preffereably with a micrometer or alternativately a very good "rack of eye " .
Pi D squared over 4 multiplied by number of strands.
6mm cable would be apoprox 0.041 inches (41 thou) or 1,04 mm, 7 strands.
rating of cooker say 16KW at 240v (IF IT IS STATED AT 240 NOT 230) would give 66.67 amps possible max load.
Diversity would say the first 10 Amps + 30% of the ramainder so.
66.67 - 10 = 56.67 * 0.3 = 17 then add back on the 10 = 27 then if a 13A socket is on the control box add 5A for occaisional use of a kettle = 32A.
6mm T & E suffices if no adverse derating for ambient temp/insulation/grouping etc applies .
This would apply to most domestics unless specific likely uses dictate otherwise.
In a nutshell then 16KW (or better still 13KW) as a rule of thumb would be OK for 6mm T & E and a 32A B type MCB unles the run is exceptionally long and would be OK all year and even forr the Xmas dinner yearly.
Actually if it does not have the socket (I hate them as it is a throwback to days of yore when you never had enough sockets and was a cheapo way for a kettle socket but unfortunately folk often use them fo washer/dryers)
then the extra 5A can be a godsend. Kettle might be 10A for a few mins
Note - if the cooker was rated at 230V you could go up sas high as 20KW with the standard (one size fits all) and no socket for kettle formula
"1) With the power off measure the diameter of the Live or Neutral conductor - the actual copper part. Not one strand - the whole lot will be OK, provided it's still twisted into an overall round shape. Then calculate the cross-sectional area"
Taking issue with you on this one mate.
Measure one strand, preffereably with a micrometer or alternativately a very good "rack of eye " .
Pi D squared over 4 multiplied by number of strands.
6mm cable would be apoprox 0.041 inches (41 thou) or 1,04 mm, 7 strands.
rating of cooker say 16KW at 240v (IF IT IS STATED AT 240 NOT 230) would give 66.67 amps possible max load.
Diversity would say the first 10 Amps + 30% of the ramainder so.
66.67 - 10 = 56.67 * 0.3 = 17 then add back on the 10 = 27 then if a 13A socket is on the control box add 5A for occaisional use of a kettle = 32A.
6mm T & E suffices if no adverse derating for ambient temp/insulation/grouping etc applies .
This would apply to most domestics unless specific likely uses dictate otherwise.
In a nutshell then 16KW (or better still 13KW) as a rule of thumb would be OK for 6mm T & E and a 32A B type MCB unles the run is exceptionally long and would be OK all year and even forr the Xmas dinner yearly.
Actually if it does not have the socket (I hate them as it is a throwback to days of yore when you never had enough sockets and was a cheapo way for a kettle socket but unfortunately folk often use them fo washer/dryers)
then the extra 5A can be a godsend. Kettle might be 10A for a few mins
Note - if the cooker was rated at 230V you could go up sas high as 20KW with the standard (one size fits all) and no socket for kettle formula
Yes - if you have access to a micrometer, or a very accurate pair of eyes.
If all you have are regular eyes, or a regular 1DP vernier caliper, then measuring the bunch, given that there are is a finite set of discrete sizes to choose from, will be fine
Where did 16kW come from? The OP's cooker is 10kW...
19.167kW actually, but it's still madness, isn't it.....
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