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Ovens and 30A fuse/feed

robopj

Hello, I googled and found some info in the old IET forums, which has generated this post.

We need to replace our double oven. For the last 20 years, a 30A trip fuse has provided power to a dual wall socket (kettle 2.2kw, microwave 1.29kw) and the oven with a 5.1kw max rated power consumption. I've discovered this by tripping the 30A fuses in the fuse box to see which appliances were still live. 

It appears that when the kitchen was fitted (20 years ago), the original standalone cooker on/off master switch was converted to a dual wall socket and the then a spur used for the double oven.

According to my maths this is a total of 35.79A @ 240v which is more than 30A, although I'm guessing the times all three appliances have been on at the same time would be infrequent.

ApplianceLoad rating (kw)Amps (at 240v)
Current oven5.121.25
Kettle2.29.166666667
Microwave1.295.375
total8.5935.79166667

Why has the 30A RCD at the fusebox not tripped when they have been on at the same time?

The new oven has a load rating of 6.2kw. This increases the total amps to just over 40A. 

ApplianceLoad rating (kw)Amps (at 240v)
New oven6.225.83333333
Kettle2.29.166666667
Microwave1.295.375
total9.6940.375

I'm guessing this may cause some issues with the 30A feed. Would a more modern 32A be better?

I suppose I could always move the kettle and microwave to other sockets in the kitchen which are on a different 30A circuit.

Please could I have your comments? 

Thank you

Paul

 

 

Parents
  • 0

    Apologies, my comments about the installation process have caused lots of feedback.

    I wish I knew how to do multiple quotes in my reply to address each point, but I cannot work it out. I'll try to clarify and respond to each post above in this post

    Existing connection

    I omitted to say that there is a isolation switch for the current double oven. The original standalone cooker switch has been converted to a double socket and a spur used to feed the double oven but there is also an isolation switch on the spur. I missed that point in my earlier posts. I think this would be an “all-pole” or “double pole / double throw" type switch but I cannot tell without removing the faceplate screws and inspecting it.

     

    0ed0a48e090a3d08cccd5d4061ec1b62-huge-image.png

     

    New double oven connection requirements

    These specify an “all-pole” isolation switch.

    9aa28f8d29c23c94a2b0f9bf5e5197d0-huge-image.png

    Comment  about  trying  to  recover  the cost  of  the second  visit  by  electrician

    I was considering the scenario where the supplier delivered; electrician attended; existing connection was OK but there was a problem with the double oven - it didn't power up. A replacement oven supplied because the first one would be rejected. The electrician would visit again. I would consider it reasonable to ask for reattendance costs for the second electrician from the supplier. Whether I'd be compensated is another matter. Others may disagree with my thinking. 

    We've ordered installation by the supplier, so providing the current electrical connection is OK, I shouldn't need to worry about anything. I tend to worry too much - hence this question :-(

    Thank you for all your comments. I think I should be OK with the installation.

    Paul

     

Reply
  • 0

    Apologies, my comments about the installation process have caused lots of feedback.

    I wish I knew how to do multiple quotes in my reply to address each point, but I cannot work it out. I'll try to clarify and respond to each post above in this post

    Existing connection

    I omitted to say that there is a isolation switch for the current double oven. The original standalone cooker switch has been converted to a double socket and a spur used to feed the double oven but there is also an isolation switch on the spur. I missed that point in my earlier posts. I think this would be an “all-pole” or “double pole / double throw" type switch but I cannot tell without removing the faceplate screws and inspecting it.

     

    0ed0a48e090a3d08cccd5d4061ec1b62-huge-image.png

     

    New double oven connection requirements

    These specify an “all-pole” isolation switch.

    9aa28f8d29c23c94a2b0f9bf5e5197d0-huge-image.png

    Comment  about  trying  to  recover  the cost  of  the second  visit  by  electrician

    I was considering the scenario where the supplier delivered; electrician attended; existing connection was OK but there was a problem with the double oven - it didn't power up. A replacement oven supplied because the first one would be rejected. The electrician would visit again. I would consider it reasonable to ask for reattendance costs for the second electrician from the supplier. Whether I'd be compensated is another matter. Others may disagree with my thinking. 

    We've ordered installation by the supplier, so providing the current electrical connection is OK, I shouldn't need to worry about anything. I tend to worry too much - hence this question :-(

    Thank you for all your comments. I think I should be OK with the installation.

    Paul

     

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