Using pre installed cooker circuit for 13amp or 16amp oven. (2)

[SUNRAY]

THAT IS A LIE.

I never give incorrect advice.

A standard cooker circuit is 32 amp. If a cooker is in 2 parts, oven and hob, a 32 amp circuit is still used. If one of the 2 parts is not it makes no difference.

An over cannot draw more than its rated current. No one has yet explained how a live to neutral fault would occur. An element failure will invariably be live to earth which will trip the RCD at around 30mA.

Much of this has been explained in the original thread by various people.

As it happens I have this heater:

Several years ago the fuse in the plug blew and Sunray being Sunray guessed the fuse had aged (let's not get into that arguement) and replaced it along with the plug as the fuse holder had gone very soft. It worked on low power which is how we tend to use it and it seemed the problem had been fixed.

Next time it was used on full power the fuse again blew after 15 minutes or so.

I checked the resistance and the 1KW element was far too low, I can't remember the values but it low was enough to be well over the 13A then adding the 1.5KW was plenty to blow the fuse.

The fault is simple, the element is horizontal open wire, some had sagged and shorted onto the lower part. I'll make the guess the airflow had been obstructed at some time and the element overheated enough before the trip popped. However it is too brittle to repair, so the solution was to remove the wire from the 1KW element leaving just the 1.5KW.

I had something similar with a tower fan heater repair, the open element was in the form of a spring running vertically, there were several mica supports holding the element every 2" or so which had broken (I suspect it had been dropped as the base was broken too) the element had sagged and about half of it was in a tangle at the bottom.

I realise modern ovens seem to use enclosed elements but that's not always been the case, certainly fan heaters and tumble driers still use open elements and I'm not aware of any reason it should not also be the case for ovens.

 

[SUNRAY]

THAT IS A LIE.

I never give incorrect advice.

A standard cooker circuit is 32 amp. If a cooker is in 2 parts, oven and hob, a 32 amp circuit is still used. If one of the 2 parts is not it makes no difference.

An over cannot draw more than its rated current. No one has yet explained how a live to neutral fault would occur. An element failure will invariably be live to earth which will trip the RCD at around 30mA.

Much of this has been explained in the original thread by various people.

As it happens I have this heater:
View attachment 234039
Several years ago the fuse in the plug blew and Sunray being Sunray guessed the fuse had aged (let's not get into that arguement) and replaced it along with the plug as the fuse holder had gone very soft. It worked on low power which is how we tend to use it and it seemed the problem had been fixed.

Next time it was used on full power the fuse again blew after 15 minutes or so.

I checked the resistance and the 1KW element was far too low, I can't remember the values but it low was enough to be well over the 13A then adding the 1.5KW was plenty to blow the fuse.

The fault is simple, the element is horizontal open wire, some had sagged and shorted onto the lower part. I'll make the guess the airflow had been obstructed at some time and the element overheated enough before the trip popped. However it is too brittle to repair, so the solution was to remove the wire from the 1KW element leaving just the 1.5KW.

I had something similar with a tower fan heater repair, the open element was in the form of a spring running vertically, there were several mica supports holding the element every 2" or so which had broken (I suspect it had been dropped as the base was broken too) the element had sagged and about half of it was in a tangle at the bottom.

I realise modern ovens seem to use enclosed elements but that's not always been the case, certainly fan heaters and tumble driers still use open elements and I'm not aware of any reason it should not also be the case for ovens.

 

[SUNRAY]

The risk/probability of some events is obviously very small. What we (and those who 'regulate' us) have to decide is where to draw lines.

It always rather amuses (and, in some senses, saddens) me if I discover that someone concerned about some risk of incredibly low probability (whether in relation to an electrical installation of anything else) is someone who smokes, drinks appreciable amounts of alcohol, is obese or ..... !!

Kind Regards, John

One of the events I was very active in we ran a 25mm swa along the back of a flower bed by a wall, well out of harms way but the H&S guy insisted we had to lift it off the ground and mark it with red and white hazard tape (Note not yellow and black). When I asked to see scaff tag for the scaffold steps they'd installed over the same wall to the organisers complex I was told of f**k off... so I asked him for his electrical qualifications and when none were forthcoming I told him to f**k off and instead powered down the cable. It fed temp power to the organisers complex, including their CCTV, radio comms etc. he changed his mind quickly.

That said, a single access track to an event site really does need the consideration of a breakdown facility.

 

[conny]

As it happens I have this heater:
View attachment 234039
Several years ago the fuse in the plug blew and Sunray being Sunray guessed the fuse had aged (let's not get into that arguement) and replaced it along with the plug as the fuse holder had gone very soft. It worked on low power which is how we tend to use it and it seemed the problem had been fixed.

Next time it was used on full power the fuse again blew after 15 minutes or so.

I checked the resistance and the 1KW element was far too low, I can't remember the values but it low was enough to be well over the 13A then adding the 1.5KW was plenty to blow the fuse.

The fault is simple, the element is horizontal open wire, some had sagged and shorted onto the lower part. I'll make the guess the airflow had been obstructed at some time and the element overheated enough before the trip popped. However it is too brittle to repair, so the solution was to remove the wire from the 1KW element leaving just the 1.5KW.

I had something similar with a tower fan heater repair, the open element was in the form of a spring running vertically, there were several mica supports holding the element every 2" or so which had broken (I suspect it had been dropped as the base was broken too) the element had sagged and about half of it was in a tangle at the bottom.

I realise modern ovens seem to use enclosed elements but that's not always been the case, certainly fan heaters and tumble driers still use open elements and I'm not aware of any reason it should not also be the case for ovens.

I used to have an electric fire with the same type of element. One day one of my mates wnted to light his ciggy but had no lighter/matches. He decided to rip a piece of paper out of his fag packet and use that as a spill. Unfortunately he thought that by rolling it up with the foil on the inside meant he would be safe from electrocution. One bang later, now sitting on his backside from a kneeling position, he realised differently.

 

[winston1]

winston1!

Please answer one simple question. If you are designing a circuit and conclude that 1.5mm² cable is the correct cable to use, what size MCB does it require?

It is not that simple as it depends on the installation method.

 

[SUNRAY]

It is not that simple as it depends on the installation method.

I totally expected you to evade answering that one and lo and behold you didn't surprise.

So what installation method would be required to allow the use of a 32A OCD

 

[winston1]

It is quite common for an oven and hob to share a 32 amp "cooker circuit". From what SUNRAY is saying this practice is wrong in case an element in one or the other goes partially short circuit, and they should be on separate 16 amp circuits.

It is also very common for an oven and hob to be built into the same box and called a cooker. Using SUNRAY's argument I would expect two sets of terminals on a cooker for connecting to two separate 16 amp circuits. Why is this not done SUNRAY?

 

[SUNRAY]

It is quite common for an oven and hob to share a 32 amp "cooker circuit". From what SUNRAY is saying this practice is wrong in case an element in one or the other goes partially short circuit, and they should be on separate 16 amp circuits.

It is also very common for an oven and hob to be built into the same box and called a cooker. Using SUNRAY's argument I would expect two sets of terminals on a cooker for connecting to two separate 16 amp circuits. Why is this not done SUNRAY?

What a load of bucking follocks your spouting.

 

[winston1]

I totally expected you to evade answering that one and lo and behold you didn't surprise.

So what installation method would be required to allow the use of a 32A OCD

I'm not evading it. You didn't supply enough information. Why is this relevant anyway? Cooker circuits are wired in 4 or 6mm cable not 1.5.

 

[winston1]

What a load of bucking follocks your spouting.

No. You mean you don't know what a cooker is?

 

[winston1]

Why don't you answer the question rather than slinging insults?

Again why are there not 2 sets of terminals on a cooker to connect to 2 separate 16 amp circuits?

 

[SUNRAY]

No. You mean you don't know what a cooker is?

Grow up, of course I know what a cooker is, of course I know what an oven is, of course I know what a hob is. I've installed plenty of them and yes I've installed ovens on 32A MCB's, and not that it's got any relevance here I've also installed ovens on 128A circuits.

Why don't you answer the question rather than slinging insults?

Again why are there not 2 sets of terminals on a cooker to connect to 2 separate 16 amp circuits?

Why should there be?

 

[winston1]

Why should there be?

Because, according to you, an oven should be on its own 16amp MCB in case an element gets a partial short.

 

[SUNRAY]

Because, according to you, an oven should be on its own 16amp MCB in case an element gets a partial short.

What a load of bucking follocks your spouting.

Nowhere have I said or even implied that.

 

[bernardgreen]

Again why are there not 2 sets of terminals on a cooker to connect to 2 separate 16 amp circuits

Remove the link between the two L terminations and then two separate cables from two separate over current protection devices ( MCB ) can be connected the one appliance.

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