Oven tripping the electrics

vacheron

Catbenetar said:

Grandad2b 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!

With all due respect to your landlord's electrician this sounds like total rubbish* to me. 
I have to admit it's been a long time since I was completely au fait with the Regs so there have been some changes I don't know about but the current carrying capacity of copper cable is determined by the laws of physics which haven't changed.

When I was a working electrician there was a thing called diversity which is what allows your sockets for example to be wired in 2.5mm^2 cable even though it can only carry (from memory) 23A.
For a cooker circuit the load was calculated as 10A + 100% of the largest ring or oven + 70% of the next largest + 30% of the rest. If there's a socket outlet at the cooker switch add 5A (I may have the percentages wrong - if so I'm sure someone will be along to correct me before the electrons are dry). Unless the cable is buried in insulation it's highly unlikely to be too small for the current you're drawing.
It's possible that this diversity formula has been changed in which case perhaps a 10mm cable may now be required.

The usual reason a 10mm cable was required was not because of current but volt drop.

However, as someone else has mentioned, this is not the cause of your tripping problem and replacing the cooker cable is unlikely to sort it.


* I was going to use a more anatomical term but it's a family forum...

The general opinion is that it is something else causing the tripping. I just don’t understand why it is only tripping when the cooker is in use. I can have absolutely everything else on at once and there will be no issues. 

It doesn’t help that I have very little understanding of how electrics work 😂 
I’m just someone who replaced a faulty oven and has seemingly now opened a can of worms. 

Though the more this thread goes on, the more I wonder if the old oven was even the issue? 

“If” it is an RCD tripping, an RCD’s job is to ensure that the live and neutral cables going through it are in balance. 

If there is an imbalance of just 30 thousandths of an amp (milliamps), it trips. 

If you remember the game buckaroo where you hang things on the horse until it jumps… well each appliance in your house is hanging a different load (imbalance) on the RCD of 1-2 ‘milliamps each (even when not being used, just plugged in and switched on is sufficient . It isn’t the last thing you hang that necessarily causes it to trip, it is  just that this final thing that took  you over the limit. 

Grandad2b

Catbenetar said:

Can I clarify something? If the oven is running on the 6mm cable and this is not big enough, would it just trip out or would there be some damage to the cable which would cause the trip as many have suggested? 

Damage to the cable insulation could occur through prolonged or repeated overloading. I don't really think this is the problem.


A true story:
Back in the late 80s I was working at a hospital which had some disused accommodation with electric cookers. In one of these the cooker was tripping out the RCD. After a little investigation we surmised that the insulation within the rings had got damp through disuse which was causing an earth fault.
Because this was an unoccupied property we decided to try to dry out the insulation by running the appliance without an earth (don't try this at home kids!) which was quite successful - after a couple of hours we checked the insulation values which had recovered to about 20 megohm and reconnected the earth; the nuisance tripping stopped. 

To clarify: the cooker was on its own dedicated circuit but the fault was neutral to earth so switching off the MCB wasn't clearing the fault. Switching off the cooker isolator meant the RCD could be turned back on and the rest of the installation could be used as normal. Naturally a note went on the file for this particular property so that anyone who found the same problem could see what we'd done.


From what you've said it sounds to me like the fault is either elsewhere on another circuit protected by the same RCD or, as someone suggested, there's a small leakage currents from various appliances including the cooker and sometimes these combine to be enough to trip the RCD. It may be that the best way you can help the electrician work out what the problem is would be to note what appliances you have running every time the circuit trips out. Without seeing the installation I can't offer a better guess.

Risteard

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.

Catbenetar

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. 

Catbenetar

vacheron said:

Catbenetar said:

Grandad2b 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!

With all due respect to your landlord's electrician this sounds like total rubbish* to me. 
I have to admit it's been a long time since I was completely au fait with the Regs so there have been some changes I don't know about but the current carrying capacity of copper cable is determined by the laws of physics which haven't changed.

When I was a working electrician there was a thing called diversity which is what allows your sockets for example to be wired in 2.5mm^2 cable even though it can only carry (from memory) 23A.
For a cooker circuit the load was calculated as 10A + 100% of the largest ring or oven + 70% of the next largest + 30% of the rest. If there's a socket outlet at the cooker switch add 5A (I may have the percentages wrong - if so I'm sure someone will be along to correct me before the electrons are dry). Unless the cable is buried in insulation it's highly unlikely to be too small for the current you're drawing.
It's possible that this diversity formula has been changed in which case perhaps a 10mm cable may now be required.

The usual reason a 10mm cable was required was not because of current but volt drop.

However, as someone else has mentioned, this is not the cause of your tripping problem and replacing the cooker cable is unlikely to sort it.


* I was going to use a more anatomical term but it's a family forum...

The general opinion is that it is something else causing the tripping. I just don’t understand why it is only tripping when the cooker is in use. I can have absolutely everything else on at once and there will be no issues. 

It doesn’t help that I have very little understanding of how electrics work 😂 
I’m just someone who replaced a faulty oven and has seemingly now opened a can of worms. 

Though the more this thread goes on, the more I wonder if the old oven was even the issue? 

“If” it is an RCD tripping, an RCD’s job is to ensure that the live and neutral cables going through it are in balance. 

If there is an imbalance of just 30 thousandths of an amp (milliamps), it trips. 

If you remember the game buckaroo where you hang things on the horse until it jumps… well each appliance in your house is hanging a different load (imbalance) on the RCD of 1-2 ‘milliamps each (even when not being used, just plugged in and switched on is sufficient . It isn’t the last thing you hang that necessarily causes it to trip, it is  just that this final thing that took  you over the limit. 

vacheron said:

Catbenetar said:

Grandad2b 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!

With all due respect to your landlord's electrician this sounds like total rubbish* to me. 
I have to admit it's been a long time since I was completely au fait with the Regs so there have been some changes I don't know about but the current carrying capacity of copper cable is determined by the laws of physics which haven't changed.

When I was a working electrician there was a thing called diversity which is what allows your sockets for example to be wired in 2.5mm^2 cable even though it can only carry (from memory) 23A.
For a cooker circuit the load was calculated as 10A + 100% of the largest ring or oven + 70% of the next largest + 30% of the rest. If there's a socket outlet at the cooker switch add 5A (I may have the percentages wrong - if so I'm sure someone will be along to correct me before the electrons are dry). Unless the cable is buried in insulation it's highly unlikely to be too small for the current you're drawing.
It's possible that this diversity formula has been changed in which case perhaps a 10mm cable may now be required.

The usual reason a 10mm cable was required was not because of current but volt drop.

However, as someone else has mentioned, this is not the cause of your tripping problem and replacing the cooker cable is unlikely to sort it.


* I was going to use a more anatomical term but it's a family forum...

The general opinion is that it is something else causing the tripping. I just don’t understand why it is only tripping when the cooker is in use. I can have absolutely everything else on at once and there will be no issues. 

It doesn’t help that I have very little understanding of how electrics work 😂 
I’m just someone who replaced a faulty oven and has seemingly now opened a can of worms. 

Though the more this thread goes on, the more I wonder if the old oven was even the issue? 

“If” it is an RCD tripping, an RCD’s job is to ensure that the live and neutral cables going through it are in balance. 

If there is an imbalance of just 30 thousandths of an amp (milliamps), it trips. 

If you remember the game buckaroo where you hang things on the horse until it jumps… well each appliance in your house is hanging a different load (imbalance) on the RCD of 1-2 ‘milliamps each (even when not being used, just plugged in and switched on is sufficient . It isn’t the last thing you hang that necessarily causes it to trip, it is  just that this final thing that took  you over the limit. 

Makes complete sense, thank you. 

So could putting the cooker on its own breaker potentially solve it? 

This still doesn’t explain (in my head) why we couldn’t switch the oven back on at the wall without everything tripping. If the oven wasn’t in use and had minimal power running through it then I don’t think it would have added too much to the load. 

Catbenetar

Grandad2b said:

Catbenetar said:

Can I clarify something? If the oven is running on the 6mm cable and this is not big enough, would it just trip out or would there be some damage to the cable which would cause the trip as many have suggested? 

Damage to the cable insulation could occur through prolonged or repeated overloading. I don't really think this is the problem.


A true story:
Back in the late 80s I was working at a hospital which had some disused accommodation with electric cookers. In one of these the cooker was tripping out the RCD. After a little investigation we surmised that the insulation within the rings had got damp through disuse which was causing an earth fault.
Because this was an unoccupied property we decided to try to dry out the insulation by running the appliance without an earth (don't try this at home kids!) which was quite successful - after a couple of hours we checked the insulation values which had recovered to about 20 megohm and reconnected the earth; the nuisance tripping stopped. 

To clarify: the cooker was on its own dedicated circuit but the fault was neutral to earth so switching off the MCB wasn't clearing the fault. Switching off the cooker isolator meant the RCD could be turned back on and the rest of the installation could be used as normal. Naturally a note went on the file for this particular property so that anyone who found the same problem could see what we'd done.


From what you've said it sounds to me like the fault is either elsewhere on another circuit protected by the same RCD or, as someone suggested, there's a small leakage currents from various appliances including the cooker and sometimes these combine to be enough to trip the RCD. It may be that the best way you can help the electrician work out what the problem is would be to note what appliances you have running every time the circuit trips out. Without seeing the installation I can't offer a better guess.

I’ve read about running with the earth disconnected, kind of makes sense, but don’t worry, I deffo won’t try it.

it has always been the oven that has caused the tripping. Nothing else has an effect on it. 

I’m thinking we have an overloaded circuit. It’s just knowing how to best sort that. 

Risteard

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".

vacheron

Catbenetar said:

vacheron said:

Catbenetar said:

Grandad2b 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!

With all due respect to your landlord's electrician this sounds like total rubbish* to me. 
I have to admit it's been a long time since I was completely au fait with the Regs so there have been some changes I don't know about but the current carrying capacity of copper cable is determined by the laws of physics which haven't changed.

When I was a working electrician there was a thing called diversity which is what allows your sockets for example to be wired in 2.5mm^2 cable even though it can only carry (from memory) 23A.
For a cooker circuit the load was calculated as 10A + 100% of the largest ring or oven + 70% of the next largest + 30% of the rest. If there's a socket outlet at the cooker switch add 5A (I may have the percentages wrong - if so I'm sure someone will be along to correct me before the electrons are dry). Unless the cable is buried in insulation it's highly unlikely to be too small for the current you're drawing.
It's possible that this diversity formula has been changed in which case perhaps a 10mm cable may now be required.

The usual reason a 10mm cable was required was not because of current but volt drop.

However, as someone else has mentioned, this is not the cause of your tripping problem and replacing the cooker cable is unlikely to sort it.


* I was going to use a more anatomical term but it's a family forum...

The general opinion is that it is something else causing the tripping. I just don’t understand why it is only tripping when the cooker is in use. I can have absolutely everything else on at once and there will be no issues. 

It doesn’t help that I have very little understanding of how electrics work 😂 
I’m just someone who replaced a faulty oven and has seemingly now opened a can of worms. 

Though the more this thread goes on, the more I wonder if the old oven was even the issue? 

“If” it is an RCD tripping, an RCD’s job is to ensure that the live and neutral cables going through it are in balance. 

If there is an imbalance of just 30 thousandths of an amp (milliamps), it trips. 

If you remember the game buckaroo where you hang things on the horse until it jumps… well each appliance in your house is hanging a different load (imbalance) on the RCD of 1-2 ‘milliamps each (even when not being used, just plugged in and switched on is sufficient . It isn’t the last thing you hang that necessarily causes it to trip, it is  just that this final thing that took  you over the limit. 

vacheron said:

Catbenetar said:

Grandad2b 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!

With all due respect to your landlord's electrician this sounds like total rubbish* to me. 
I have to admit it's been a long time since I was completely au fait with the Regs so there have been some changes I don't know about but the current carrying capacity of copper cable is determined by the laws of physics which haven't changed.

When I was a working electrician there was a thing called diversity which is what allows your sockets for example to be wired in 2.5mm^2 cable even though it can only carry (from memory) 23A.
For a cooker circuit the load was calculated as 10A + 100% of the largest ring or oven + 70% of the next largest + 30% of the rest. If there's a socket outlet at the cooker switch add 5A (I may have the percentages wrong - if so I'm sure someone will be along to correct me before the electrons are dry). Unless the cable is buried in insulation it's highly unlikely to be too small for the current you're drawing.
It's possible that this diversity formula has been changed in which case perhaps a 10mm cable may now be required.

The usual reason a 10mm cable was required was not because of current but volt drop.

However, as someone else has mentioned, this is not the cause of your tripping problem and replacing the cooker cable is unlikely to sort it.


* I was going to use a more anatomical term but it's a family forum...

The general opinion is that it is something else causing the tripping. I just don’t understand why it is only tripping when the cooker is in use. I can have absolutely everything else on at once and there will be no issues. 

It doesn’t help that I have very little understanding of how electrics work 😂 
I’m just someone who replaced a faulty oven and has seemingly now opened a can of worms. 

Though the more this thread goes on, the more I wonder if the old oven was even the issue? 

“If” it is an RCD tripping, an RCD’s job is to ensure that the live and neutral cables going through it are in balance. 

If there is an imbalance of just 30 thousandths of an amp (milliamps), it trips. 

If you remember the game buckaroo where you hang things on the horse until it jumps… well each appliance in your house is hanging a different load (imbalance) on the RCD of 1-2 ‘milliamps each (even when not being used, just plugged in and switched on is sufficient . It isn’t the last thing you hang that necessarily causes it to trip, it is  just that this final thing that took  you over the limit. 

Makes complete sense, thank you. 

So could putting the cooker on its own breaker potentially solve it? 

This still doesn’t explain (in my head) why we couldn’t switch the oven back on at the wall without everything tripping. If the oven wasn’t in use and had minimal power running through it then I don’t think it would have added too much to the load. 

It’s going to get techie fast, but input filters have capacitive and inductive elements connected to earth which leak, but these can really leak when the mains is first switched on and there is an inrush of current. 

Also, modern appliances are always “on’ to some) degree (sensors, clocks, displays, timers even when is primary function (heating) is not in use. 

For another analogy, imagine a garden hose with a bad tap end connector. This will still drip (leak) at a fairly constant rate whether the end you are spraying the garden with is closed shut off or jetting loads of water (power) . 

Putting it on its own RCD would solve that problem as then the cooker would have the whole 30mA all for itself. At the moment it has to share it with all the other kitchen appliances and whatever is connected to the other sockets it feeds. 

Catbenetar

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? 

Catbenetar

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.