Oven tripping the electrics

FreeBear

Catbenetar said:

Risteard said:

Catbenetar said:

Risteard said:

Catbenetar said:

If anyone is still following I do have an update.

We had an electrician out who said the wiring is too small to accommodate a 10kw oven. The installer really ought to have spotted this at the time it was put in. 

Our options are to either try and get another oven (though most are around 10 so this will be a struggle) or have a new cable run from the oven to the fuse box. 

Nightmare!

This sounds exceedingly unlikely. I presume 10kW is listed as the "total connected load". It seems inconceivable to me that an oven would be in any way capable of having a consumption of anything like 10kW (notwithstanding the likes of commercial ovens). Do you have makes and model numbers of the oven(s) and hob(s) connected to the existing cooker circuit? A typical 32A cooker circuit is typically considered to be suitable for around 15kW of cooking equipment.

Hi, 
The cooker is an Amica 601SS. The listing on curry’s says it has an electrical power rating of 10kw and power supply of 45amp. 

A direct quote from the manual for that: "Connection shuld be made with 4 mm2 twin and earth cable."

Also from that manual: "The power supply cable must have these minimum requirements:
- Type: HO5VV-F (PVC insulated and sheathed flexible cable)
- 3 cores x 4 mm2 ."

As I say, the usual would be a 6mm^2 supply on a 32A protective device, with 4mm^2 flexible cable for the final connection. There is no need for 10mm^2 (unless the cable has been installed through thermal insulation etc. which should instead be avoided). The equipment cannot draw 10kW (and certainly not for any prolonged period). That will be the "total connected load".

So the 6mm is fine for the power coming from the oven? The electrician is incorrect? 

Depends on the length of cable. Short runs of (say) 3m wouldn't be a problem. But if the cable between consumer unit & isolator switch is for example) 20m, then 10mm² may be required.

The isolator switch should be reasonably close to the cooker, so that short run (1-2m ?) can be 6mm².

Might be an idea to swap the shower MCB with the boiler so that it isn't on the same RCD. Generally not a good idea to group all the high current circuits together.

Catbenetar

FreeBear said:

Catbenetar said:

Risteard said:

Catbenetar said:

Risteard said:

Catbenetar said:

If anyone is still following I do have an update.

We had an electrician out who said the wiring is too small to accommodate a 10kw oven. The installer really ought to have spotted this at the time it was put in. 

Our options are to either try and get another oven (though most are around 10 so this will be a struggle) or have a new cable run from the oven to the fuse box. 

Nightmare!

This sounds exceedingly unlikely. I presume 10kW is listed as the "total connected load". It seems inconceivable to me that an oven would be in any way capable of having a consumption of anything like 10kW (notwithstanding the likes of commercial ovens). Do you have makes and model numbers of the oven(s) and hob(s) connected to the existing cooker circuit? A typical 32A cooker circuit is typically considered to be suitable for around 15kW of cooking equipment.

Hi, 
The cooker is an Amica 601SS. The listing on curry’s says it has an electrical power rating of 10kw and power supply of 45amp. 

A direct quote from the manual for that: "Connection shuld be made with 4 mm2 twin and earth cable."

Also from that manual: "The power supply cable must have these minimum requirements:
- Type: HO5VV-F (PVC insulated and sheathed flexible cable)
- 3 cores x 4 mm2 ."

As I say, the usual would be a 6mm^2 supply on a 32A protective device, with 4mm^2 flexible cable for the final connection. There is no need for 10mm^2 (unless the cable has been installed through thermal insulation etc. which should instead be avoided). The equipment cannot draw 10kW (and certainly not for any prolonged period). That will be the "total connected load".

So the 6mm is fine for the power coming from the oven? The electrician is incorrect? 

Depends on the length of cable. Short runs of (say) 3m wouldn't be a problem. But if the cable between consumer unit & isolator switch is for example) 20m, then 10mm² may be required.

The isolator switch should be reasonably close to the cooker, so that short run (1-2m ?) can be 6mm².

Might be an idea to swap the shower MCB with the boiler so that it isn't on the same RCD. Generally not a good idea to group all the high current circuits together.

Thanks for the reply. We have estimated that the cable length could be around 8m if we are correct on the path. 

danrv

Catbenetar said:

Morning all, here are some pictures of my fuse box. The blue switch to the right of the cooker is what trips. The shower was added right before the issues began, but we were assured this was nothing to do with it. 

The oven does have a dedicated circuit. Turn off all MCB switches on that side and turn back on one at a time to see when the RCD trips.

Catbenetar

These are the installation instructions from the old cooker which we believe to be defective. 

What size cable would have been appropriate? 

Catbenetar

danrv said:

Catbenetar said:

Morning all, here are some pictures of my fuse box. The blue switch to the right of the cooker is what trips. The shower was added right before the issues began, but we were assured this was nothing to do with it. 

The oven does have a dedicated circuit. Turn off all MCB switches on that side and turn back on one at a time to see when the RCD trips.

Do you think the circuit could be overloaded? 

danrv

Catbenetar said:

danrv said:

Catbenetar said:

Morning all, here are some pictures of my fuse box. The blue switch to the right of the cooker is what trips. The shower was added right before the issues began, but we were assured this was nothing to do with it. 

The oven does have a dedicated circuit. Turn off all MCB switches on that side and turn back on one at a time to see when the RCD trips.

Do you think the circuit could be overloaded? 

No, that would trip one of MCB switches on an individual circuit. It's a ground fault caused by damaged insulation somewhere, either in the wiring, switch, appliance or water ingress. 

The cable for the oven is likely to be 6mm T&E which is fine. 10mm not needed.
If switching each circuit off and then on again on the CU points to the oven being at fault, the cable and switch to it needs to be checked.

Grandad2b

Catbenetar said:

Morning all, here are some pictures of my fuse box. The blue switch to the right of the cooker is what trips. The shower was added right before the issues began, but we were assured this was nothing to do with it. 

The RCD is tripping.

The cooker is on a separate circuit for power but not for earth leakage current. Getting the cooker onto its own RCD would mean that it wouldn't affect the others.

Catbenetar

danrv said:

Catbenetar said:

danrv said:

Catbenetar said:

Morning all, here are some pictures of my fuse box. The blue switch to the right of the cooker is what trips. The shower was added right before the issues began, but we were assured this was nothing to do with it. 

The oven does have a dedicated circuit. Turn off all MCB switches on that side and turn back on one at a time to see when the RCD trips.

Do you think the circuit could be overloaded? 

No, that would trip one of MCB switches on an individual circuit. It's a ground fault caused by damaged insulation somewhere, either in the wiring, switch, appliance or water ingress. 

The cable for the oven is likely to be 6mm T&E which is fine. 10mm not needed.
If switching each circuit off and then on again on the CU points to the oven being at fault, the cable and switch to it needs to be checked.

We have had the cable from the switch to the cooker changed. It was borderline apparently so he switched it. No other faults detected on the rest of the line (this has been checked twice now). 

In theory now things should work fine. 

I might now carry on a normal and await the next trip. See what happens regarding the cooker then. 

vacheron

My guess is changing that cable to 10mm will NOT prevent the issue reoccurring as the problem to me is earth leakage not overload. 

If it was overload the cooker MCB would trip first well before the cable was overloaded as it is rated to trip at 32 Amps (7.4KW) which 6mm twin and earth can easily handle..

Your useful photos show you have a split RCD consumer unit with the cooker, “kitchen and bedroom sockets”,“downstairs lights” AND shower ALL running through the RIGHT RCD (leak detector), ( the one with the yellow button). 

All the MCB’s to the left of the LEFT RCD run through that one.

You have also confirmed it is indeed the RCD that is tripping.

When (not if 😉) it trips again, please tell the electrician to read my very first reply to your original post. 😁

Risteard

Catbenetar said:

Risteard said:

Catbenetar said:

Risteard said:

Catbenetar said:

If anyone is still following I do have an update.

We had an electrician out who said the wiring is too small to accommodate a 10kw oven. The installer really ought to have spotted this at the time it was put in. 

Our options are to either try and get another oven (though most are around 10 so this will be a struggle) or have a new cable run from the oven to the fuse box. 

Nightmare!

This sounds exceedingly unlikely. I presume 10kW is listed as the "total connected load". It seems inconceivable to me that an oven would be in any way capable of having a consumption of anything like 10kW (notwithstanding the likes of commercial ovens). Do you have makes and model numbers of the oven(s) and hob(s) connected to the existing cooker circuit? A typical 32A cooker circuit is typically considered to be suitable for around 15kW of cooking equipment.

Hi, 
The cooker is an Amica 601SS. The listing on curry’s says it has an electrical power rating of 10kw and power supply of 45amp. 

A direct quote from the manual for that: "Connection shuld be made with 4 mm2 twin and earth cable."

Also from that manual: "The power supply cable must have these minimum requirements:
- Type: HO5VV-F (PVC insulated and sheathed flexible cable)
- 3 cores x 4 mm2 ."

As I say, the usual would be a 6mm^2 supply on a 32A protective device, with 4mm^2 flexible cable for the final connection. There is no need for 10mm^2 (unless the cable has been installed through thermal insulation etc. which should instead be avoided). The equipment cannot draw 10kW (and certainly not for any prolonged period). That will be the "total connected load".

So the 6mm is fine for the power coming from the oven? The electrician is incorrect? 

The obvious caveat is that I'm not familiar with the particular installation in question, but it is highly probable that it is adequate.