electric cooker

[saleem]

HI,i have got new Range master proffesional deluxe 100 dual feul cooker.before we had gas only range master cooker.we thought it could be with normal plug so one could plug o
it into ring main but its not the case here.cookers total load is GRILL,2.3kw MAIN OVEN,3.7kw and tall oven is 2.5kw that includes lights and fan etc.so total load is aprox..8.8kw.distance from CU to switch is about 8 meters.CU is split load 80/80.we have 45 amp spare rcd.question is what size cable is needed.instruction book says min 6mm and max 10mm.is 45 amp not too over rated.CU is about 1 meter above floor level and cable drops down in celler where it can be cliped under joists.celler is not working one it is only used by going down through trap door.is it ok to take cable from cu to cooker switch and then to cooker or we need back plate before making connection to cooker.any help is appriciated.thanks

 

[PrenticeBoyofDerry]

40A MCB will do you on 6mm cable.
6.00mm T&E will carry a maximum of 47A. The maximum load demand would be 38.3A.
You could get away with the 45A. MCB as the cable will safely carry this, given the information given and the appliance on full load will ask for no more than 38.3A
I assume no thermal insulation along route of cable

 

[saleem]

40A MCB will do you on 6mm cable.
6.00mm T&E will carry a maximum of 47A. The maximum load demand would be 38.3A.
You could get away with the 45A. MCB as the cable will safely carry this, given the information given and the appliance on full load will ask for no more than 38.3A
I assume no thermal insulation along route of cable

thanks for quick response.cable be about 1 meter in trunking from CU then it goes in celler very cold plenty of fresh air circulation.appears in kitchen then again 1 meter in trunking.which cooker switch is better.single 45 amp double pole or the one with socket switch.do we need back plate connection or cooker can be connected from switch.lastely is 40 amp mcb preferable over 45 amp which we already have in place.once again many thanks.

 

[EFLImpudence]

Because of the trunking you will have to have a 32A MCB installed or 10mm² cable.

Switch without a socket would be better and a connector plate behind the cooker is easier to connect and alter in the future.

 

[saleem]

Because of the trunking you will have to have a 32A MCB installed or 10mm² cable.

Switch without a socket would be better and a connector plate behind the cooker is easier to connect and alter in the future.

HI.as earliar post suggests as total appliance consumption is no more than 38.3 amp,40 amp or even 45 amp is suffitient with 6mm cable.is 32 amp mcb not too under rated.few years back we had single tower cooker fitted 32 amp mcb and 6mm cable.are you saying 32 amp mcb with 6mm cable or 10mm cable with what size mcb is a must.

 

[EFLImpudence]

32A MCB and 6mm² cable will be fine for your cooker.

Total may be 38A but because of 'diversity', (that is allowing for the fact that all the loads will not be on at the same time) 32A MCB is normal for a cooker.

 

[PrenticeBoyofDerry]

cable be about 1 meter in trunking from CU then it goes in celler very cold plenty of fresh air circulation.appears in kitchen then again 1 meter in trunking.which cooker switch is better.single 45 amp double pole or the one with socket switch.do we need back plate connection or cooker can be connected from switch.lastely is 40 amp mcb preferable over 45 amp which we already have in place.once again many thanks.

As the cable is routed in trunking during some of its route, there will be a de-rating factor of the cable current carrying capacity, as mentioned by EFLImpudence. This will reduce the capacity of the 6.00mm cable from 47A to 38A. So therefore a MCB higher than that rating is unsuitable.
So you either increase cable size or reduce MCB rating.

HI.as earliar post suggests as total appliance consumption is no more than 38.3 amp, 40 amp or even 45 amp is suffitient with 6mm cable.is 32 amp mcb not too under rated.few years back we had single tower cooker fitted 32 amp mcb and 6mm cable.are you saying 32 amp mcb with 6mm cable or 10mm cable with what size mcb is a must.

Diversity can be offered to cooking appliances, which assumes that all output power will not be used at any one given time. As it is highly unlikely that your appliance will be on maximum load, it is acceptable to offer diversity to the circuit.
It is acceptable to have a 32A MCB protecting a circuit supplying a cooker with the output of up to 15kW.
So 32A can be used or cable will need upgrading.

 

[saleem]

32A MCB and 6mm² cable will be fine for your cooker.

Total may be 38A but because of 'diversity', (that is allowing for the fact that all the loads will not be on at the same time) 32A MCB is normal for a cooker.

Hi,as you mentioned here that all loads will not be on at the same time 32A mcb is normal for cooker.we have large family and quite often all loads do stay on at the same time.today i was chating to an electrition at my work place and i mentioned to him.he said should use 10mm cable and 45A MCB.not40 or 32A.you be pushing with 6mm cable on 32 A MCB.bit confusing.

 

[EFLImpudence]

He is wrong.

 

[JohnD]

cooker elements are controlled by thermostats. So each of them will be on for a bit, off for a bit, on for a bit, off for a bit. Even when the control knob is set to full on.

It would be fairly difficult to synchronise them so that they were all drawing power at the same time, and for long enough to trip the MCB.

The person you spoke to sounds like he is not familiar with domestic cooker loads.

He also needs to look up the rating for 6mm T&E, and check what derating factors apply in your installation.

 

[saleem]

cooker elements are controlled by thermostats. So each of them will be on for a bit, off for a bit, on for a bit, off for a bit. Even when the control knob is set to full on.

It would be fairly difficult to synchronise them so that they were all drawing power at the same time, and for long enough to trip the MCB.

The person you spoke to sounds like he is not familiar with domestic cooker loads.

He also needs to look up the rating for 6mm T&E, and check what derating factors apply in your installation.

so we can have 6mm cable on 32A MCB.no worries and no false tripping.thanks.